Skeptical Scenarios

I promised to return to some of the issues discussed here. The current post addresses the implications of the sort of skeptical scenario considered by Alexander Pruss in the associated discussion. Consider his original comparison of physical theories and skeptical scenarios:

The ordinary sentence “There are four chairs in my office” is true (in its ordinary context). Furthermore, its being true tells us very little about fundamental ontology. Fundamental physical reality could be made out of a single field, a handful of fields, particles in three-dimensional space, particles in ten-dimensional space, a single vector in a Hilbert space, etc., and yet the sentence could be true.

An interesting consequence: Even if in fact physical reality is made out of particles in three-dimensional space, we should not analyze the sentence to mean that there are four disjoint pluralities of particles each arranged chairwise in my office. For if that were what the sentence meant, it would tell us about which of the fundamental physical ontologies is correct. Rather, the sentence is true because of a certain arrangement of particles (or fields or whatever).

If there is such a broad range of fundamental ontologies that “There are four chairs in my office” is compatible with, it seems that the sentence should also be compatible with various sceptical scenarios, such as that I am a brain in a vat being fed data from a computer simulation. In that case, the chair sentence would be true due to facts about the computer simulation, in much the way that “There are four chairs in this Minecraft house” is true. It would be very difficult to be open to a wide variety of fundamental physics stories about the chair sentence without being open to the sentence being true in virtue of facts about a computer simulation.

If we consider this in light of our analysis of form, it is not difficult to see that Pruss is correct both about the ordinary chair sentence being consistent with a large variety of physical theories, and about the implication that it is consistent with most situations that would normally be considered “skeptical.” The reason is that to say that something is a chair is to say something about its relationships with the world, but it is not to say everything about its relationships. It speaks in particular about various relationships with the human world. And there is nothing to prevent these relationships from co-existing with any number of other kinds of relationships between its parts, its causes, and so on.

Pruss is right to insist that in order for the ordinary sentence to be true, the corresponding forms must be present. But as an anti-reductionist, his position implies hidden essences, and this is a mistake. Indeed, under the correct understanding of form, our everyday knowledge of things is sufficient to ensure that the forms are present: regardless of which physical theories turn out to be true, and even if some such skeptical scenario turns out to be true.

Why are these situations called “skeptical” in the first place? This is presumably because they seem to call into question whether or not we possess any knowledge of things. And in this respect, they fail in two ways, they partially fail in a third, and they succeed in one way.

First, they fail insofar as they attempt to call into question, e.g. whether there are chairs in my room right now, or whether I have two hands. These things are true and would be true even in the “skeptical” situations.

Second, they fail even insofar as they claim, e.g. that I do not know whether I am a brain in a vat. In the straightforward sense, I do know this, because the claim is opposed to the other things (e.g. about the chairs and my hands) that I know to be true.

Third, they partially fail even insofar as they claim, e.g. that I do not know whether I am a brain in a vat in a metaphysical sense. Roughly speaking, I do know that I am not, not by deducing the fact with any kind of necessity, but simply because the metaphysical claim is completely ungrounded. In other words, I do not know this infallibly, but it is extremely likely. We could compare this with predictions about the future. Thus for example Ron Conte attempts to predict the future:

First, an overview of the tribulation:
A. The first part of the tribulation occurs for this generation, beginning within the next few years, and ending in 2040 A.D.
B. Then there will be a brief period of peace and holiness on earth, lasting about 25 years.
C. The next few hundred years will see a gradual but unstoppable increase in sinfulness and suffering in the world. The Church will remain holy, and Her teaching will remain pure. But many of Her members will fall into sin, due to the influence of the sinful world.
D. The second part of the tribulation occurs in the early 25th century (about 2430 to 2437). The Antichrist reigns for less than 7 years during this time.
E. Jesus Christ returns to earth, ending the tribulation.

Now, some predictions for the near future. These are not listed in chronological order.

* The Warning, Consolation, and Miracle — predicted at Garabandal and Medjugorje — will occur prior to the start of the tribulation, sometime within the next several years (2018 to 2023).
* The Church will experience a severe schism. First, a conservative schism will occur, under Pope Francis; next, a liberal schism will occur, under his conservative successor.
* The conservative schism will be triggered by certain events: Amoris Laetitia (as we already know, so, not a prediction), and the approval of women deacons, and controversial teachings on salvation theology.
* After a short time, Pope Francis will resign from office.
* His very conservative successor will reign for a few years, and then die a martyr, during World War 3.
* The successor to Pope Francis will take the papal name Pius XIII.

Even ignoring the religious speculation, we can “know” that this account is false, simply because it is inordinately detailed. Ron Conte no doubt has reasons for his beliefs, much as the Jehovah’s Witnesses did. But just as we saw in that case, his reasons will also in all likelihood turn out to be completely disproportionate to the detail of the claims they seek to establish.

In a similar way, a skeptical scenario can be seen as painting a detailed picture of a larger context of our world, one outside our current knowledge. There is nothing impossible about such a larger context; in fact, there surely is one. But the claim about brains and vats is very detailed: if one takes it seriously, it is more detailed than Ron Conte’s predictions, which could also be taken as a statement about a larger temporal context to our situation. The brain-in-vat scenario implies that our entire world depends on another world which has things similar to brains and similar to vats, along presumably with things analogous to human beings that made the vats, and so on. And since the whole point of the scenario is that it is utterly invented, not that it is accepted by anyone, while Conte’s account is accepted at least by him, there is not even a supposed basis for thinking that things are actually this way. Thus we can say, not infallibly but with a great deal of certainty, that we are not brains in vats, just as we can say, not infallibly but with a great deal of certainty, that there will not be any “Antichrist” between 2430 and 2437.

There is nonetheless one way in which the consideration of skeptical scenarios does succeed in calling our knowledge into question. Consider them insofar as they propose a larger context to our world, as discussed above. As I said, there is nothing impossible about a larger context, and there surely is one. Here we speak of a larger metaphysical context, but we can compare this with the idea of a larger physical context.

Our knowledge of our physical context is essentially local, given the concrete ways that we come to know the world. I know a lot about the room I am in, a significant amount about the places I usually visit or have visited in the past, and some but much less about places I haven’t visited. And speaking of an even larger physical context, I know things about the solar system, but much less about the wider physical universe. And if we consider what lies outside the visible universe, I might well guess that there are more stars and galaxies and so on, but nothing more. There is not much more detail even to this as a guess: and if there is an even larger physical context, it is possible that there are places that do not have stars and galaxies at all, but other things. In other words, universal knowledge is universal, but also vague, while specific knowledge is more specific, but also more localized: it is precisely because it is local that it was possible to acquire more specific knowledge.

In a similar way, more specific metaphysical knowledge is necessarily of a more local metaphysical character: both physical and metaphysical knowledge is acquired by us through the relationships things have with us, and in both cases “with us” implies locality. We can know that the brain-in-vat scenario is mistaken, but that should not give us hope that we can find out what is true instead: even if we did find some specific larger metaphysical context to our situation, there would be still larger contexts of which we would remain unaware. Just as you will never know the things that are too distant from you physically, you will also never know the things that are too distant from you metaphysically.

I previously advocated patience as a way to avoid excessively detailed claims. There is nothing wrong with this, but here we see that it is not enough: we also need to accept our actual situation. Rebellion against our situation, in the form of painting a detailed picture of a larger context of which we can have no significant knowledge, will profit us nothing: it will just be painting a picture as false as the brain-in-vat scenario, and as false as Ron Conte’s predictions.

Advertisements

Nature of Form

We add one final claim to the list in the last post:

(8) Form is a network of relationships apt to make something one.

I will approach this in the manner of a disputed question, first raising a number of objections, then giving my explanation and replies to the objections.

Objection 1. According to this definition, form consists of many relations. But form makes a thing one. Thus form should not be in itself many, such as many relationships are, since many things are composed of units.

Objection 2. The definition begs the question by saying “apt to make something one.” Form is supposed to make things one, but if we want to say something about the nature of form, we should explain exactly how and why it does this.

Objection 3. A “network of relationships” might be some kind of form, but it seems to be an accidental form, not a substantial form, while the definition of form should be general enough to include both.

Objection 4. A thing can have the relations it has because of its particular nature. Therefore its nature cannot be defined by its relationships, since this would be circular. Thus form cannot be a network of relationships.

Objection 5. The definition is implicitly reductionist, and therefore opposed to thesis (4). For a composite thing, whether animal or artifact or anything else, will have many relations among its parts which define it, but it can be looked at and considered in many ways, while what appears to be most real must be its most basic parts, such as atoms or quarks or whatever.

Objection 6. Form seems to be unknown to us in a way in which the content of this definition is not, and therefore they must be somehow distinct. For example, whatever might be said about the definitions of blue proposed in the last post, it is clear that something is lacking there. There is something about the nature of blue that is quite unknown to us. So it seems unlikely that blue can be defined in the way proposed, and similarly unlikely that form can be defined as a network of relationships.

Objection 7. Christians, at least, must reject this definition, along with thesis (3), since the essence of God cannot be naturally known by human beings. Therefore God has a hidden essence, and since it is entirely simple, it cannot be a network of relationships.

Objection 8. This definition implies that the human soul is like a harmony, with all the consequences suggested by Simmias in the Phaedo, namely that the soul is mortal. So again Christians, at least, must reject this definition.

Objection 9. Composite things are made of both form and matter, so a relationship to matter should be included in the definition of form.

Objection 10. The network of relationships seems to be a construct of the mind more than a real thing. So one should reject this definition together with rejecting thesis (4), since what a thing really is, is something more basic that causes these relationships.

Objection 11. The definition might be true of material things, but if there are any immaterial things, it will not apply to them. Instead, they might well exist in themselves, without relation to other things, or at least not being defined by such relations. Likewise thesis (3) should probably be denied in relation to such things.

But let us go on to the explanation of this definition. If we consider the question, “what is form?”, one might immediately see a problem. Form is supposed to provide us the answer to the question about what a thing is, so if we ask what form is, we would seem to need a form of form. And even if this is possible, it is a process that cannot possibly go on forever, and therefore we will reach a point where we cannot find a form of form, and therefore we will not be able to answer the question. This is a complex issue which I will set aside for now, simply remarking for now that the question “what is this” needs to be answered in different ways for different things, including for form itself.

At the same time, however, the arguments of the previous post imply that form is accessible to us, and that we can know it both specifically and in general. Essences are not hidden from us, and it is form that both gives a thing the essence it has and that makes us understand. And since it is the very thing that is present in our mind when we understand the thing, it should be just as accessible to us as the contents of our own mind. In other words, we can say what a form is by answering the question, “What does my mind have in common with this thing when I understand it?” And thus we can answer the general question about form by noticing what our minds have in common with things they understand in general.

This answer is implicit in the discussion of thesis (7) in the last post. We noted in the case of “blue” that what both the senses and the mind have in common with things is a certain relation or network of relationships, namely those that correspond to the relations possessed by things apt to be seen by the sight as blue. And this will always be the case whenever we understand anything, since our understanding will always produce a sort of “model” of the thing understood. This is necessary since the understanding does not become an actual copy of the thing; such a becoming would in fact exclude understanding. If your mind literally became a tree when it attempted to understand it, you would understand nothing, since trees do not understand.

This applies at many levels. For example, not only does it apply to meaning and understanding, in some way it applies even to our language on the level of syntax. For example, Word2vec is famously capable of producing analogies which somewhat reflect analogies between the things signified, even though the meanings of the words are absent from its analysis. We should not stress this too much, however, since this takes a very small subset of relationships, even a small subset of relationships found in language, and shows how they will have a structural similarity to their causes. In a sense this does mean that the forms of things are present in linguistic syntax, but it is a very attenuated sense. In contrast, the forms of things are fully present in our understanding to the precise degree that we understand them. The qualification is important: we don’t understand anything perfectly, and consequently no form should be expected to be found perfectly in our understanding.

Others have suggested similar ideas about the natures of things. For example, Sean Collins says:

But for now I will set that aside and come to what I should like to propose as the heart of my thesis. I mentioned a moment ago that Scholastic thought has always acknowledged a dependence of the qualitative on the quantitative. There are many things, nevertheless, which we may recognize without really grasping their full implications. This brings me to what my son Liam wanted to say about form. He proposed, seemingly rather starkly, that there is no such thing as form in material things. But I believe what he meant is that there is cannot be a form in the manner frequently assumed; and I think he is absolutely right. What do I mean by “the manner frequently assumed”? What I mean is that we can cheerfully assert that quality, and therefore also substance, depends on quantity, but yet not see what this really means. What it means – what science proves over and over again – is not just that quality and substance depend on form externally as it were, but that they depend on it much more internally, which is to say structurally. In other words, in material things, form turns out not only to be compatible with an internal structure and heterogeneity, but to depend on it profoundly. I want to say in effect that in material things, to a surprisingly large extent, form IS structure. And so a conception of form which unifies things to the exclusion of a structure is a false conception.

You will perhaps recognize that this solves some problems, but raises others. The biggest problem that it solves is that very Scholastic principle that I have been referring to, which is that quality and substance, the more formal principles, depend on quantity. Now we can start to affirm that we know a little better what that really means. What it means is not just that things have to “be the right size,” but rather that quality and substance depend on quantity internally, because it is quantity that makes structure possible; and structure is, if you will, the intermediary between matter and whatever more abstract kind of form we may have yet to consider. And what I want to insist on again is that this structure is not a negligible thing; in fact it is so important that scientists spend a very large portion of their time examining it. Without it we could know, did know, only the first rudiments of how material things are made. And so this is why the metric part of scientific investigation acquires such a prominent aspect; it isn’t because that is all that the scientists are interested in or that they arbitrarily restrict themselves to it; on the contrary, it is because that is the very condition upon which an understanding of material forms hinges. In various places, Aristotle notes that there is a real difference between a mere dialectical or logical investigation of physical reality, and a truly physical one. The latter, as Aristotle understands it, depends on a sufficient accounting of the material aspects of things so that we can begin to see how forms are truly materialized. Now we can see perhaps a little better how this materialization of forms really happens. It happens especially through the understanding of quantitative structure.

Sean Collins is speaking about material things in particular, and structure as quantitative. My account is similar but more general: if there are any immaterial things, or things without quantity, it applies to them as well. Thus I speak of a network of relationships, of which “quantitative structure” would be more like a particular example.

Paul Almond gives a similar account:

Reality can only be meaningfully described in terms of relationships between things and internal properties of things. That being the case, why do we take the approach of reducing everything to relationships only, so that the “things” being connected by the relationships have no internal properties and all that exists is the structure of relationships itself? The idea of reducing everything to relationships only has been proposed by Tegmark. Suppose reality were viewed as a structure of relationships between things that had internal properties. Those internal properties could themselves only be described in terms of relationships between things. This means that we would have a structure of relationships between “things” and, inside each such “thing” there would also be a structure of relationships between some more basic entities. We would have no reason for declaring a boundary between the relationships outside the “thing” and the relationships inside the “thing”. Instead, we could just take the “edge of a thing” away and say that whatever relationships existed within a thing were just part of the external structure of relationships. The end result of this is that the “things” connected by these relationships have no internal properties at all. All that is left is a structure of relationships between points that have no internal properties. All that remains is the structure itself.

Almond gives this as an account of reality as such, while we give it as an account of form. This is not entirely the same, and consequently Almond’s account could be taken as denying the existence of matter, much like Alexander Pruss. This will be discussed more in my response to objection 9, but my account is not intended to reject the existence of matter. Nonetheless, matter does not contribute to the intelligibility of a thing, and it is therefore true in a sense that form is “most of” reality.

This kind of account is sometimes taken to imply that our understanding is entirely and permanently superficial. For example, Bertrand Russell says in The Analysis of Matter (page 10):

Physics, in itself, is exceedingly abstract, and reveals only certain mathematical characteristics of the material with which it deals. It does not tell us anything as to the intrinsic character of this material.

While mathematical physics as such does have specific limitations, both by reason of the mathematical approach and by the deliberate limitation of subject implied in “physics,” there is a more general problem here. Any account whatsoever of a thing will explain that thing in relationship to everything else, without giving an account of the “intrinsic character of this material.” But this is not because we are necessarily failing to account for something. It is because this is what it is to give an account at all, and because the network of relationships really is the what it is to be of the thing. There is no hidden essence, and the appearance that there must be some other nature, more fundamental, but which cannot be found by us, derives from a temptation towards the Kantian error. The thing does indeed exist in itself, and its mode of existence is not our mode of understanding, but this does not necessarily mean we do not understand it. On the contrary, this distinction is absolutely necessary for understanding at all.

The replies to the objections will be in another post, and as is usual with a disputed question, will clarify various aspects of this position.

Hard Problem of Consciousness

We have touched on this in various places, and in particular in this discussion of zombies, but we are now in a position to give a more precise answer.

Bill Vallicella has a discussion of Thomas Nagel on this issue:

Nagel replies in the pages of NYRB (8 June 2017; HT: Dave Lull) to one Roy Black, a professor of bioengineering:

The mind-body problem that exercises both Daniel Dennett and me is a problem about what experience is, not how it is caused. The difficulty is that conscious experience has an essentially subjective character—what it is like for its subject, from the inside—that purely physical processes do not share. Physical concepts describe the world as it is in itself, and not for any conscious subject. That includes dark energy, the strong force, and the development of an organism from the egg, to cite Black’s examples. But if subjective experience is not an illusion, the real world includes more than can be described in this way.

I agree with Black that “we need to determine what ‘thing,’ what activity of neurons beyond activating other neurons, was amplified to the point that consciousness arose.” But I believe this will require that we attribute to neurons, and perhaps to still more basic physical things and processes, some properties that in the right combination are capable of constituting subjects of experience like ourselves, to whom sunsets and chocolate and violins look and taste and sound as they do. These, if they are ever discovered, will not be physical properties, because physical properties, however sophisticated and complex, characterize only the order of the world extended in space and time, not how things appear from any particular point of view.

The problem might be condensed into an aporetic triad:

1) Conscious experience is not an illusion.

2) Conscious experience has an essentially subjective character that purely physical processes do not share.

3) The only acceptable explanation of conscious experience is in terms of physical properties alone.

Take a little time to savor this problem. Note first that the three propositions are collectively inconsistent: they cannot all be true.  Any two limbs entail the negation of the remaining one. Note second that each limb exerts a strong pull on our acceptance.  But we cannot accept them all because they are logically incompatible.

Which proposition should we reject? Dennett, I take it, would reject (1). But that’s a lunatic solution as Professor Black seems to appreciate, though he puts the point more politely. When I call Dennett a sophist, as I have on several occasions, I am not abusing him; I am underscoring what is obvious, namely, that the smell of cooked onions, for example, is a genuine datum of experience, and that such phenomenological data trump scientistic theories.

Sophistry aside, we either reject (2) or we reject (3).  Nagel and I accept (1) and (2) and reject (3). Black, and others of the scientistic stripe, accept (1) and (3) and reject (2).

In order to see the answer to this, we can construct a Parmenidean parallel to Vallicella’s aporetic triad:

1) Distinction is not an illusion.

2) Being has an essentially objective character of actually being that distinction does not share (considering that distinction consists in the fact of not being something.)

3) The only acceptable explanation of distinction is in terms of being alone (since there is nothing but being to explain things with.)

Parmenides rejects (1) here. What approach would Vallicella take? If he wishes to take a similarly analogous approach, he should accept (1) and (2), and deny (3). And this would be a pretty commonsense approach, and perhaps the one that most people implicitly adopt if they ever think about the problem.

At the same time, it is easy to see that (3) is approximately just as obviously true as (1); and it is for this reason that Parmenides sees rejecting (1) and accepting (2) and (3) as reasonable.

The correct answer, of course, is that the three are not inconsistent despite appearances. In fact, we have effectively answered this in recent posts. Distinction is not an illusion, but a way that we understand things, as such. And being a way of understanding, it is not (as such) a way of being mistaken, and thus it is not an illusion, and thus the first point is correct. Again, being a way of understanding, it is not a way of being as such, and thus the second point is correct. And yet distinction can be explained by being, since there is something (namely relationship) which explains why it is reasonable to think in terms of distinctions.

Vallicella’s triad mentions “purely physical processes” and “physical properties,” but the idea of “physical” here is a distraction, and is not really relevant to the problem. Consider the following from another post by Vallicella:

If I understand Galen Strawson’s view, it is the first.  Conscious experience is fully real but wholly material in nature despite the fact that on current physics we cannot account for its reality: we cannot understand how it is possible for qualia and thoughts to be wholly material.   Here is a characteristic passage from Strawson:

Serious materialists have to be outright realists about the experiential. So they are obliged to hold that experiential phenomena just are physical phenomena, although current physics cannot account for them.  As an acting materialist, I accept this, and assume that experiential phenomena are “based in” or “realized in” the brain (to stick to the human case).  But this assumption does not solve any problems for materialists.  Instead it obliges them to admit ignorance of the nature of the physical, to admit that they don’t have a fully adequate idea of what the physical is, and hence of what the brain is.  (“The Experiential and the Non-Experiential” in Warner and Szubka, p. 77)

Strawson and I agree on two important points.  One is that what he calls experiential phenomena are as real as anything and cannot be eliminated or reduced to anything non-experiential. Dennett denied! The other is that there is no accounting for experiential items in terms of current physics.

I disagree on whether his mysterian solution is a genuine solution to the problem. What he is saying is that, given the obvious reality of conscious states, and given the truth of naturalism, experiential phenomena must be material in nature, and that this is so whether or not we are able to understand how it could be so.  At present we cannot understand how it could be so. It is at present a mystery. But the mystery will dissipate when we have a better understanding of matter.

This strikes me as bluster.

An experiential item such as a twinge of pain or a rush of elation is essentially subjective; it is something whose appearing just is its reality.  For qualia, esse = percipi.  If I am told that someday items like this will be exhaustively understood from a third-person point of view as objects of physics, I have no idea what this means.  The notion strikes me as absurd.  We are being told in effect that what is essentially subjective will one day be exhaustively understood as both essentially subjective and wholly objective.  And that makes no sense. If you tell me that understanding in physics need not be objectifying understanding, I don’t know what that means either.

Here Vallicella uses the word “material,” which is presumably equivalent to “physical” in the above discussion. But it is easy to see here that being material is not the problem: being objective is the problem. Material things are objective, and Vallicella sees an irreducible opposition between being objective and being subjective. In a similar way, we can reformulate Vallicella’s original triad so that it does not refer to being physical:

1) Conscious experience is not an illusion.

2) Conscious experience has an essentially subjective character that purely objective processes do not share.

3) The only acceptable explanation of conscious experience is in terms of objective properties alone.

It is easy to see that this formulation is the real source of the problem. And while Vallicella would probably deny (3) even in this formulation, it is easy to see why people would want to accept (3). “Real things are objective,” they will say. If you want to explain anything, you should explain it using real things, and therefore objective things.

The parallel with the Parmenidean problem is evident. We would want to explain distinction in terms of being, since there isn’t anything else, and yet this seems impossible, so one (e.g. Parmenides) is tempted to deny the existence of distinction. In the same way, we would want to explain subjective experience in terms of objective facts, since there isn’t anything else, and yet this seems impossible, so one (e.g. Dennett) is tempted to deny the existence of subjective experience.

Just as the problem is parallel, the correct solution will be almost entirely parallel to the solution to the problem of Parmenides.

1) Conscious experience is not an illusion. It is a way of perceiving the world, not a way of not perceiving the world, and definitely not a way of not perceiving at all.

2) Consciousness is subjective, that is, it is a way that an individual perceives the world, not a way that things are as such, and thus not an “objective fact” in the sense that “the way things are” is objective.

3) The “way things are”, namely the objective facts, are sufficient to explain why individuals perceive the world. Consider again this post, responding to a post by Robin Hanson. We could reformulate his criticism to express instead Parmenides’s criticism of common sense (changed parts in italics):

People often state things like this:

I am sure that there is not just being, because I’m aware that some things are not other things. I know that being just isn’t non-being. So even though there is being, there must be something more than that to reality. So there’s a deep mystery: what is this extra stuff, where does it arise, how does it change, and so on. We humans care about distinctions, not just being; we want to know what out there is distinct from which other things.

But consider a key question: Does this other distinction stuff interact with the parts of our world that actually exist strongly and reliably enough to usually be the actual cause of humans making statements of distinction like this?

If yes, this is a remarkably strong interaction, making it quite surprising that philosophers, possibly excepting Duns Scotus, have missed it so far. So surprising in fact as to be frankly unbelievable. If this type of interaction were remotely as simple as all the interactions we know, then it should be quite understandable with existing philosophy. Any interaction not so understandable would have be vastly more difficult to understand than any we’ve ever seen or considered. Thus I’d bet heavily and confidently that no one will understand such an interaction.

But if no, if this interaction isn’t strong enough to explain human claims of distinction, then we have a remarkable coincidence to explain. Somehow this extra distinction stuff exists, and humans also have a tendency to say that it exists, but these happen for entirely independent reasons. The fact that distinction stuff exists isn’t causing people to claim it exists, nor vice versa. Instead humans have some sort of weird psychological quirk that causes them to make such statements, and they would make such claims even if distinction stuff didn’t exist. But if we have a good alternate explanation for why people tend to make such statements, what need do we have of the hypothesis that distinction stuff actually exists? Such a coincidence seems too remarkable to be believed.

“Distinction stuff”, of course, does not exist, and neither does “feeling stuff.” But some things are distinct from others. Saying this is a way of understanding the world, and it is a reasonable way to understand the world because things exist relative to one another. And just as one thing is distinct from another, people have experiences. Those experiences are ways of knowing the world (broadly understood.) And just as reality is sufficient to explain distinction, so reality is sufficient to explain the fact that people have experiences.

How exactly does this answer the objection about interaction? In the case of distinction, the fact that “one thing is not another” is never the direct cause of anything, not even of the fact that “someone believes that one thing is not another.” So there would seem to be a “remarkable coincidence” here, or we would have to say that since the fact seems unrelated to the opinion, there is no reason to believe people are right when they make distinctions.

The answer in the case of distinction is that one thing is related to another, and this fact is the cause of someone believing that one thing is not another. There is no coincidence, and no reason to believe that people are mistaken when they make distinctions, despite the fact that distinction as such causes nothing.

In a similar way, “a human being is what it is,” and “a human being does what it does” (taken in an objective sense), cause human beings to say and believe that they have subjective experience (taking saying and believing to refer to objective facts.) But this is precisely where the zombie question arises: they say and believe that they have subjective experience, when we interpret say and believe in the objective sense. But do they actually say and believe anything, considering saying and believing as including the subjective factor? Namely, when a non-zombie says something, it subjectively understands the meaning of what it is saying, and when it consciously believes something, it has a subjective experience of doing that, but these things would not apply to a zombie.

But notice that we can raise a similar question about zombie distinctions. When someone says and believes that one thing is not another, objective reality is similarly the cause of them making the distinction. But is the one thing actually not the other? But there is no question at all here except of whether the person’s statement is true or false. And indeed, someone can say, e.g, “The person who came yesterday is not the person who came today,” and this can sometimes be false. In a similar way, asking whether an apparent person is a zombie or not is just asking whether their claim is true or false when they say they have a subjective experience. The difference is that if the (objective) claim is false, then there is no claim at all in the subjective sense of “subjectively claiming something.” It is a contradiction to subjectively make the false claim that you are subjectively claiming something, and thus, this cannot happen.

Someone may insist: you yourself, when you subjectively claim something, cannot be mistaken for the above reason. But you have no way to know whether someone else who apparently is making that claim, is actually making the claim subjectively or not. This is the reason there is a hard problem.

How do we investigate the case of distinction? If we want to determine whether the person who came yesterday is not the person who came today, we do that by looking at reality, despite the fact that distinction as such is not a part of reality as such. If the person who came yesterday is now, today, a mile away from the person who came today, this gives us plenty of reason to say that the one person is not the other. There is nothing strange, however, in the fact that there is no infallible method to prove conclusively, once and for all, that one thing is definitely not another thing. There is not therefore some special “hard problem of distinction.” This is just a result of the fact that our knowledge in general is not infallible.

In a similar way, if we want to investigate whether something has subjective experience or not, we can do that only by looking at reality: what is this thing, and what does it do? Then suppose it makes an apparent claim that it has subjective experience. Obviously, for the above reasons, this cannot be a subjective claim but false: so the question is whether it makes a subjective claim and is right, or rather makes no subjective claim at all. How would you answer this as an external observer?

In the case of distinction, the fact that someone claims that one thing is distinct from another is caused by reality, whether the claim is true or false. So whether it is true or false depends on the way that it is caused by reality. In a similar way, the thing which apparently and objectively claims to possess subjective experience, is caused to do so by objective facts. Again, as in the case of distinction, whether it is true or false will depend on the way that it is caused to do so by objective facts.

We can give some obvious examples:

“This thing claims to possess subjective experience because it is a human being and does what humans normally do.” In this case, the objective and subjective claim is true, and is caused in the right way by objective facts.

“This thing claims to possess subjective experience because it is a very simple computer given a very simple program to output ‘I have subjective experience’ on its screen.” In this case the external claim is false, and it is caused in the wrong way by objective facts, and there is no subjective claim at all.

But how do you know for sure, someone will object. Perhaps the computer really is conscious, and perhaps the apparent human is a zombie. But we could similarly ask how we can know for sure that the person who came yesterday isn’t the same person who came today, even though they appear distant from each other, because perhaps the person is bilocating?

It would be mostly wrong to describe this situation by saying “there really is no hard problem of consciousness,” as Robin Hanson appears to do when he says, “People who think they can conceive of such zombies see a ‘hard question’ regarding which physical systems that claim to feel and otherwise act as if they feel actually do feel.” The implication seems to be that there is no hard question at all. But there is, and the fact that people engage in this discussion proves the existence of the question. Rather, we should say that the question is answerable, and that one it has been answered the remaining questions are “hard” only in the sense that it is hard to understand the world in general. The question is hard in exactly the way the question of Parmenides is hard: “How is it possible for one thing not to be another, when there is only being?” The question of consciousness is similar: “How is it possible for something to have subjective experience, when there are only objective things?” And the question can and should be answered in a similar fashion.

It would be virtually impossible to address every related issue in a simple blog post of this form, so I will simply mention some things that I have mainly set aside here:

1) The issue of formal causes, discussed more in my earlier treatment of this issue. This is relevant because “is this a zombie?” is in effect equivalent to asking whether the thing lacks a formal cause. This is worthy of a great deal of consideration and would go far beyond either this post or the earlier one.

2) The issue of “physical” and “material.” As I stated in this post, this is mainly a distraction. Most of the time, the real question is how the subjective is possible given that we believe that the world is objective. The only relevance of “matter” here is that it is obvious that a material thing is an objective thing. But of course, an immaterial thing would also have to be objective in order to be a thing at all. Aristotle and many philosophers of his school make the specific argument that the human mind does not have an organ, but such arguments are highly questionable, and in my view fundamentally flawed. My earlier posts suffice to call such a conclusion into question, but do not attempt to disprove it, and the the topic would be worthy of additional consideration.

3) Specific questions about “what, exactly, would actually be conscious?” Now neglecting such questions might seem to be a cop-out, since isn’t this what the whole problem was supposed to be in the first place? But in a sense we did answer it. Take an apparent claim of something to be conscious. The question would be this: “Given how it was caused by objective facts to make that claim, would it be a reasonable claim for a subjective claimer to make?” In other words, we cannot assume in advance that it is subjectively making a claim, but if it would be a reasonable claim, it will (in general) be a true one, and therefore also a subjective one, for the same reason that we (in general) make true claims when we reasonably claim that one thing is not another. We have not answered this question only in the same sense that we have not exhaustively explained which things are distinct from which other things, and how one would know. But the question, e.g., “when if ever would you consider an artificial intelligence to be conscious?” is in itself also worthy of direct discussion.

4) The issue of vagueness. This issue in particular will cause some people to object to my answer here. Thus Alexander Pruss brings this up in a discussion of whether a computer could be conscious:

Now, intelligence could plausibly be a vague property. But it is not plausible that consciousness is a vague property. So, there must be some precise transition point in reliability needed for computation to yield consciousness, so that a slight decrease in reliability—even when the actual functioning is unchanged (remember that the Ci are all functioning in the same way)—will remove consciousness.

I responded in the comments there:

The transition between being conscious and not being conscious that happens when you fall asleep seems pretty vague. I don’t see why you find it implausible that “being conscious” could be vague in much the same way “being red” or “being intelligent” might be vague. In fact the evidence from experience (falling asleep etc) seems to directly suggest that it is vague.

Pruss responds:

When I fall asleep, I may become conscious of less and less. But I can’t get myself to deny that either it is definitely true at any given time that I am at least a little conscious or it is definitely true that I am not at all conscious.

But we cannot trust Pruss’s intuitions about what can be vague or otherwise. Pruss claims in an earlier post that there is necessarily a sharp transition between someone’s not being old and someone’s being old. I discussed that post here. This is so obviously false that it gives us a reason in general not to trust Alexander Pruss on the issue of sharp transitions and vagueness. The source of this particular intuition may be the fact that you cannot subjectively make a claim, even vaguely, without some subjective experience, as well as his general impression that vagueness violates the principles of excluded middle and non-contradiction. But in a similar way, you cannot be vaguely old without being somewhat old. This does not mean that there is a sharp transition from not being old to being old, and likewise it does not necessarily mean that there is a sharp transition from not having subjective experience to having it.

While I have discussed the issue of vagueness elsewhere on this blog, this will probably continue to be a reoccurring feature, if only because of those who cannot accept this feature of reality and insist, in effect, on “this or nothing.”

Mary’s Surprising Response

In Consciousness Explained, Daniel Dennett proposes the following continuation to the story of Mary’s room:

And so, one day, Mary’s captors decided it was time for her to see colors. As a trick, they prepared a bright blue banana to present as her first color experience ever. Mary took one look at it and said “Hey! You tried to trick me! Bananas are yellow, but this one is blue!” Her captors were dumfounded. How did she do it? “Simple,” she replied. “You have to remember that I know everything—absolutely everything—that could ever be known about the physical causes and effects of color vision. So of course before you brought the banana in, I had already written down, in exquisite detail, exactly what physical impression a yellow object or a blue object (or a green object, etc.) would make on my nervous system. So I already knew exactly what thoughts I would have (because, after all, the “mere disposition” to think about this or that is not one of your famous qualia, is it?). I was not in the slightest surprised by my experience of blue (what surprised me was that you would try such a second-rate trick on me). I realize it is hard for you to imagine that I could know so much about my reactive dispositions that the way blue affected me came as no surprise. Of course it’s hard for you to imagine. It’s hard for anyone to imagine the consequences of someone knowing absolutely everything physical about anything!”

I don’t intend to fully analyze this scenario here, and for that reason I left it to the reader in the previous post. However, I will make two remarks, one on what is right (or possibly right) about this continuation, and one on what might be wrong about this continuation.

The basically right or possibly right element is that if we assume that Mary knows all there is to know about color, including in its subjective aspect, it is reasonable to believe (even if not demonstrable) that she will be able to recognize the colors the first time she sees them. To gesture vaguely in this direction, we might consider that the color red can be somewhat agitating, while green and blue can be somewhat calming. These are not metaphorical associations, but actual emotional effects that they can have. Thus, if someone can recognize how their experience is affecting their emotions, it would be possible for them to say, “this seems more like the effect I would expect of green or blue, rather than red.” Obviously, this is not proving anything. But then, we do not in fact know what it is like to know everything there is to know about anything. As Dennett continues:

Surely I’ve cheated, you think. I must be hiding some impossibility behind the veil of Mary’s remarks. Can you prove it? My point is not that my way of telling the rest of the story proves that Mary doesn’t learn anything, but that the usual way of imagining the story doesn’t prove that she does. It doesn’t prove anything; it simply pumps the intuition that she does (“it seems just obvious”) by lulling you into imagining something other than what the premises require.

It is of course true that in any realistic, readily imaginable version of the story, Mary would come to learn something, but in any realistic, readily imaginable version she might know a lot, but she would not know everything physical. Simply imagining that Mary knows a lot, and leaving it at that, is not a good way to figure out the implications of her having “all the physical information”—any more than imagining she is filthy rich would be a good way to figure out the implications of the hypothesis that she owned everything.

By saying that the usual way of imagining the story “simply pumps the intuition,” Dennett is neglecting to point out what is true about the usual way of imagining the situation, and in that way he makes his own account seem less convincing. If Mary knows in advance all there is to know about color, then of course if she is asked afterwards, “do you know anything new about color?”, she will say no. But if we simply ask, “Is there anything new here?”, she will say, “Yes, I had a new experience which I never had before. But intellectually I already knew all there was to know about that experience, so I have nothing new to say about it. Still, the experience as such was new.” We are making the same point here as in the last post. Knowing a sensible experience intellectually is not to know in the mode of sense knowledge, but in the mode of intellectual knowledge. So if one then engages in sense knowledge, there will be a new mode of knowing, but not a new thing known. Dennett’s account would be clearer and more convincing if he simply agreed that Mary will indeed acknowledge something new; just not new knowledge.

In relation to what I said might be wrong about the continuation, we might ask what Dennett intended to do in using the word “physical” repeatedly throughout this account, including in phrases like “know everything physical” and “all the physical information.” In my explanation of the continuation, I simply assume that Mary understands all that can be understood about color. Dennett seems to want some sort of limitation to the “physical information” that can be understood about color. But either this is a real limitation, excluding some sorts of claims about color, or it is no limitation at all. If it is not a limitation, then we can simply say that Mary understands everything there is to know about color. If it is a real limitation, then the continuation will almost certainly fail.

I suspect that the real issue here, for Dennett, is the suggestion of some sort of reductionism. But reductionism to what? If Mary is allowed to believe things like, “Most yellows typically look brighter than most blue things,” then the limit is irrelevant, and Mary is allowed to know anything that people usually know about colors. But if the meaning is that Mary knows this only in a mathematical sense, that is, that she can have beliefs about certain mathematical properties of light and surfaces, rather than beliefs that are explicitly about blue and yellow things, then it will be a real limitation, and this limitation would cause his continuation to fail. We have basically the same issue here that I discussed in relation to Robin Hanson on consciousness earlier. If all of Mary’s statements are mathematical statements, then of course she will not know everything that people know about color. “Blue is not yellow” is not a mathematical statement, and it is something that we know about color. So we already know from the beginning that not all the knowledge that can be had about color is mathematical. Dennett might want to insist that it is “physical,” and surely blue and yellow are properties of physical things. If that is all he intends to say, namely that the properties she knows are properties of physical things, there is no problem here, but it does look like he intends to push further, to the point of possibly asserting something that would be evidently false.

Truth in Ordinary Language

After the incident with the tall man, I make plans to meet my companion the following day. “Let us meet at sunrise tomorrow,” I say. They ask in response, “How will I know when the sun has risen?”

When it is true to say that the sun will rise, or that the sun has risen? And what it would take for such statements to be false?

Virtually no one finds themselves uncomfortable with this language despite the fact that the sun has no physical motion called “rising,” but rather the earth is rotating, giving the appearance of movement to the sun. I will ignore issues of relativity, precisely because they are evidently irrelevant. It is not just that the sun is not moving, but that we know that the physical motion of the sun one way or another is irrelevant. The rising of the sun has nothing to do with a deep physical or metaphysical account of the sun as such. Instead, it is about that thing that happens every morning. What would it take for it to be false that the sun will rise tomorrow? Well, if the earth is destroyed today, then presumably the sun will not rise tomorrow. Or if tomorrow it is dark at noon and everyone on Twitter is on an uproar about the fact that the sun is visible at the height of the sky at midnight in their part of the world, then it will have been false that the sun was going to rise in the morning. In other words, the only possible thing that could falsify the claim about the sun would be a falsification of our expectations about our experience of the sun.

As in the last post, however, this does not mean that the statement about the sun is about our expectations. It is about the sun. But the only thing it says about the sun is something like, “The sun will be and do whatever it needs to, including in relative terms, in order for our ordinary experience of a sunrise to be as it usually is.” I said something similar here about the truth of attributions of sensible qualities, such as when we say that “the banana is yellow.”

All of this will apply in general to all of our ordinary language about ourselves, our lives, and the world.

Idealized Idealization

On another occasion, I discussed the Aristotelian idea that the act of the mind does not use an organ. In an essay entitled Immaterial Aspects of Thought, James Ross claims that he can establish the truth of this position definitively. He summarizes the argument:

Some thinking (judgment) is determinate in a way no physical process can be. Consequently, such thinking cannot be (wholly) a physical process. If all thinking, all judgment, is determinate in that way, no physical process can be (the whole of) any judgment at all. Furthermore, “functions” among physical states cannot be determinate enough to be such judgments, either. Hence some judgments can be neither wholly physical processes nor wholly functions among physical processes.

Certain thinking, in a single case, is of a definite abstract form (e.g. N x N = N²), and not indeterminate among incompossible forms (see I below). No physical process can be that definite in its form in a single case. Adding cases even to infinity, unless they are all the possible cases, will not exclude incompossible forms. But supplying all possible cases of any pure function is impossible. So, no physical process can exclude incompossible functions from being equally well (or badly) satisfied (see II below). Thus, no physical process can be a case of such thinking. The same holds for functions among physical states (see IV below).

In essence, the argument is that squaring a number and similar things are infinitely precise processes, and no physical process is infinitely precise. Therefore squaring a number and similar things are not physical processes.

The problem is unfortunately with the major premise here. Squaring a number, and similar things, in the way that we in fact do them, are not infinitely precise processes.

Ross argues that they must be:

Can judgments really be of such definite “pure” forms? They have to be; otherwise, they will fail to have the features we attribute to them and upon which the truth of certain judgments about validity, inconsistency, and truth depend; for instance, they have to exclude incompossible forms or they would lack the very features we take to be definitive of their sorts: e.g., conjunction, disjunction, syllogistic, modus ponens, etc. The single case of thinking has to be of an abstract “form” (a “pure” function) that is not indeterminate among incompossible ones. For instance, if I square a number–not just happen in the course of adding to write down a sum that is a square, but if I actually square the number–I think in the form “N x N = N².”

The same point again. I can reason in the form, modus ponens (“If p then q“; “p“; “therefore, q”). Reasoning by modus ponens requires that no incompossible forms also be “realized” (in the same sense) by what I have done. Reasoning in that form is thinking in a way that is truth-preserving for all cases that realize the form. What is done cannot, therefore, be indeterminate among structures, some of which are not truth preserving. That is why valid reasoning cannot be only an approximation of the form, but must be of the form. Otherwise, it will as much fail to be truth-preserving for all relevant cases as it succeeds; and thus the whole point of validity will be lost. Thus, we already know that the evasion, “We do not really conjoin, add, or do modus ponens but only simulate them,” cannot be correct. Still, I shall consider it fully below.

“It will as much fail to be truth-preserving for all relevant cases as it succeeds” is an exaggeration here. If you perform an operation which approximates modus ponens, then that operation will be approximately truth preserving. It will not be equally truth preserving and not truth preserving.

I have noted many times in the past, as for example here, here, here, and especially here, that following the rules of syllogism does not in practice infallibly guarantee that your conclusions are true, even if your premises are in some way true, because of the vagueness of human thought and language. In essence, Ross is making a contrary argument: we know, he is claiming, that our arguments infallibly succeed; therefore our thoughts cannot be vague. But it is empirically false that our arguments infallibly succeed, so the argument is mistaken right from its starting point.

There is also a strawmanning of the opposing position here insofar as Ross describes those who disagree with him as saying that “we do not really conjoin, add, or do modus ponens but only simulate them.” This assumes that unless you are doing these things perfectly, rather than approximating them, then you are not doing them at all. But this does not follow. Consider a triangle drawn on a blackboard. Consider which of the following statements is true:

  1. There is a triangle drawn on the blackboard.
  2. There is no triangle drawn on the blackboard.

Obviously, the first statement is true, and the second false. But in Ross’s way of thinking, we would have to say, “What is on the blackboard is only approximately triangular, not exactly triangular. Therefore there is no triangle on the blackboard.” This of course is wrong, and his description of the opposing position is wrong in the same way.

Naturally, if we take “triangle” as shorthand for “exact rather than approximate triangle” then (2) will be true. And in a similar way, if take “really conjoin” and so on as shorthand for “really conjoin exactly and not approximately,” then those who disagree will indeed say that we do not do those things. But this is not a problem unless you are assuming from the beginning that our thoughts are infinitely precise, and Ross is attempting to establish that this must be the case, rather than claiming to take it as given. (That is, the summary takes it as given, but Ross attempts throughout the article to establish it.)

One could attempt to defend Ross’s position as follows: we must have infinitely precise thoughts, because we can understand the words “infinitely precise thoughts.” Or in the case of modus ponens, we must have an infinitely precise understanding of it, because we can distinguish between “modus ponens, precisely,” and “approximations of modus ponens“. But the error here is similar to the error of saying that one must have infinite certainty about some things, because otherwise one will not have infinite certainty about the fact that one does not have infinite certainty, as though this were a contradiction. It is no contradiction for all of your thoughts to be fallible, including this one, and it is no contradiction for all of your thoughts to be vague, including your thoughts about precision and approximation.

The title of this post in fact refers to this error, which is probably the fundamental problem in Ross’s argument. Triangles in the real world are not perfectly triangular, but we have an idealized concept of a triangle. In precisely the same way, the process of idealization in the real world is not an infinitely precise process, but we have an idealized concept of idealization. Concluding that our acts of idealization must actually be ideal in themselves, simply because we have an idealized concept of idealization, would be a case of confusing the way of knowing with the way of being. It is a particularly confusing case simply because the way of knowing in this case is also materially the being which is known. But this material identity does not make the mode of knowing into the mode of being.

We should consider also Ross’s minor premise, that a physical process cannot be determinate in the way required:

Whatever the discriminable features of a physical process may be, there will always be a pair of incompatible predicates, each as empirically adequate as the other, to name a function the exhibited data or process “satisfies.” That condition holds for any finite actual “outputs,” no matter how many. That is a feature of physical process itself, of change. There is nothing about a physical process, or any repetitions of it, to block it from being a case of incompossible forms (“functions”), if it could be a case of any pure form at all. That is because the differentiating point, the point where the behavioral outputs diverge to manifest different functions, can lie beyond the actual, even if the actual should be infinite; e.g., it could lie in what the thing would have done, had things been otherwise in certain ways. For instance, if the function is x(*)y = (x + y, if y < 10^40 years, = x + y +1, otherwise), the differentiating output would lie beyond the conjectured life of the universe.

Just as rectangular doors can approximate Euclidean rectangularity, so physical change can simulate pure functions but cannot realize them. For instance, there are no physical features by which an adding machine, whether it is an old mechanical “gear” machine or a hand calculator or a full computer, can exclude its satisfying a function incompatible with addition, say quaddition (cf. Kripke’s definition of the function to show the indeterminacy of the single case: quus, symbolized by the plus sign in a circle, “is defined by: x quus y = x + y, if x, y < 57, =5 otherwise”) modified so that the differentiating outputs (not what constitutes the difference, but what manifests it) lie beyond the lifetime of the machine. The consequence is that a physical process is really indeterminate among incompatible abstract functions.

Extending the list of outputs will not select among incompatible functions whose differentiating “point” lies beyond the lifetime (or performance time) of the machine. That, of course, is not the basis for the indeterminacy; it is just a grue-like illustration. Adding is not a sequence of outputs; it is summing; whereas if the process were quadding, all its outputs would be quadditions, whether or not they differed in quantity from additions (before a differentiating point shows up to make the outputs diverge from sums).

For any outputs to be sums, the machine has to add. But the indeterminacy among incompossible functions is to be found in each single case, and therefore in every case. Thus, the machine never adds.

There is some truth here, and some error here. If we think about a physical process in the particular way that Ross is considering it, it will be true that it will always be able to be interpreted in more than one way. This is why, for example, in my recent discussion with John Nerst, John needed to say that the fundamental cause of things had to be “rules” rather than e.g. fundamental particles. The movement of particles, in itself, could be interpreted in various ways. “Rules,” on the other hand, are presumed to be something which already has a particular interpretation, e.g. adding as opposed to quadding.

On the other hand, there is also an error here. The prima facie sign of this error is the statement that an adding machine “never adds.” Just as according to common sense we can draw triangles on blackboards, so according to common sense the calculator on my desk can certainly add. This is connected with the problem with the entire argument. Since “the calculator can add” is true in some way, there is no particular reason that “we can add” cannot be true in precisely the same way. Ross wishes to argue that we can add in a way that the calculator cannot because, in essence, we do it infallibly; but this is flatly false. We do not do it infallibly.

Considered metaphysically, the problem here is ignorance of the formal cause. If physical processes were entirely formless, they indeed would have no interpretation, just as a formless human (were that possible) would be a philosophical zombie. But in reality there are forms in both cases. In this sense, Ross’s argument comes close to saying “human thought is a form or formed, but physical processes are formless.” Since in fact neither is formless, there is no reason (at least established by this argument) why thought could not be the form of a physical process.

 

The Actual Infinite

There are good reasons to think that actual infinities are possible in the real world. In the first place, while the size and shape of the universe are not settled issues, the generally accepted theory fits better with the idea that the universe is physically infinite than with the idea that it is finite.

Likewise, the universe is certainly larger than the size of the observable universe, namely about 93 billion light years in diameter. Supposing you have a probability distribution which assigns a finite probability to the claim that the universe is physically infinite, there is no consistent probability distribution which will not cause the probability of an infinite universe to go to 100% at the limit, as you exclude smaller finite sizes. But if someone had assigned a reasonable probability distribution before modern physical science existed, it would very likely have been one that make the probability of an infinite universe go very high by the time the universe was confirmed to be its present size. Therefore we too should think that the universe is very probably infinite. In principle, this argument is capable of refuting even purported demonstrations of the impossibility of an actual infinite, since there is at least some small chance that these purported demonstrations are all wrong.

Likewise, almost everyone accepts the possibility of an infinite future. Even the heat death of the universe would not prevent the passage of infinite time, and a religious view of the future also generally implies the passage of infinite future time. Even if heaven is supposed to be outside time in principle, in practice there would still be an infinite number of future human acts. If eternalism or something similar is true, then an infinite future in itself implies an actual infinite. And even if such a theory is not true, it is likely that a potentially infinite future implies the possibility of an actual infinite, because any problematic or paradoxical results from an actual infinite can likely be imitated in some way in the case of an infinite future.

On the other hand, there are good reasons to think that actual infinities are not possible in the real world. Positing infinities results in paradoxical or contradictory results in very many cases, and the simplest and therefore most likely way to explain this is to admit that infinities are simply impossible in general, even in the cases where we have not yet verified this fact.

An actual infinite also seems to imply an infinite regress in causality, and such a regress is impossible. We can see this by considering the material cause. Suppose the universe is physically infinite, and contains an infinite number of stars and planets. Then the universe is composed of the solar system together with the rest of the universe. But the rest of the universe will be composed of another stellar system together with the remainder, and so on. So there will be an infinite regress of material causality, which is just as impossible with material causality as with any other kind of causality.

Something similar is implied by St. Thomas’s argument against an infinite multitude:

This, however, is impossible; since every kind of multitude must belong to a species of multitude. Now the species of multitude are to be reckoned by the species of numbers. But no species of number is infinite; for every number is multitude measured by one. Hence it is impossible for there to be an actually infinite multitude, either absolute or accidental.

We can look at this in terms of our explanation of defining numbers. This explanation works only for finite numbers, and an infinite number could not be defined in such a way, precisely because it would result in an infinite regress. This leads us back to the first argument above against infinities: an infinity is intrinsically undefined and unintelligible, and for that reason leads to paradoxes. Someone might say that something unintelligible cannot be understood but is not impossible; but this is no different from Bertrand Russell saying that there is no reason for things not to come into being from nothing, without a cause. Such a position is unreasonable and untrue.