Semi-Parmenidean Heresy

In his book The Big Picture, Sean Carroll describes the view which he calls “poetic naturalism”:

As knowledge generally, and science in particular, have progressed over the centuries, our corresponding ontologies have evolved from quite rich to relatively sparse. To the ancients, it was reasonable to believe that there were all kinds of fundamentally different things in the world; in modern thought, we try to do more with less.

We would now say that Theseus’s ship is made of atoms, all of which are made of protons, neutrons, and electrons-exactly the same kinds of particles that make up every other ship, or for that matter make up you and me. There isn’t some primordial “shipness” of which Theseus’s is one particular example; there are simply arrangements of atoms, gradually changing over time.

That doesn’t mean we can’t talk about ships just because we understand that they are collections of atoms. It would be horrendously inconvenient if, anytime someone asked us a question about something happening in the world, we limited our allowable responses to a listing of a huge set of atoms and how they were arranged. If you listed about one atom per second, it would take more than a trillion times the current age of the universe to describe a ship like Theseus’s. Not really practical.

It just means that the notion of a ship is a derived category in our ontology, not a fundamental one. It is a useful way of talking about certain subsets of the basic stuff of the universe. We invent the concept of a ship because it is useful to us, not because it’s already there at the deepest level of reality. Is it the same ship after we’ve gradually replaced every plank? I don’t know. It’s up to us to decide. The very notion of “ship” is something we created for our own convenience.

That’s okay. The deepest level of reality is very important; but all the different ways we have of talking about that level are important too.

There is something essentially pre-Socratic about this thinking. When Carroll talks about “fundamentally different things,” he means things that differ according to their basic elements. But at the same kind the implication is that only things that differ in this way are “fundamentally” different in the sense of being truly or really different. But this is a quite different sense of “fundamental.”

I suggested in the linked post that even Thales might not really have believed that material causes alone sufficiently explained reality. Nonetheless, there was a focus on the material cause as being the truest explanation. We see the same focus here in Sean Carroll. When he says, “There isn’t some primordial shipness,” he is thinking of shipness as something that would have to be a material cause, if it existed.

Carroll proceeds to contrast his position with eliminativism:

One benefit of a rich ontology is that it’s easy to say what is “real”- every category describes something real. In a sparse ontology, that’s not so clear. Should we count only the underlying stuff of the world as real, and all the different ways we have of dividing it up and talking about it as merely illusions? That’s the most hard-core attitude we could take to reality, sometimes called eliminativism, since its adherents like nothing better than to go around eliminating this or that concept from our list of what is real. For an eliminativist, the question “Which Captian Kirk is the real one?” gets answered by, “Who cares? People are illusions. They’re just fictitious stories we tell about the one true world.”

I’m going to argue for a different view: our fundamental ontology, the best way we have of talking about the world at the deepest level, is extremely sparse. But many concepts that are part of non-fundamental ways we have of talking about the world- useful ideas describing higher-level, macroscopic reality- deserve to be called “real.”

The key word there is “useful.” There are certainly non-useful ways of talking about the world. In scientific contexts, we refer to such non-useful ways as “wrong” or “false.” A way of talking isn’t just a list of concepts; it will generally include a set of rules for using them, and relationships among them. Every scientific theory is a way of talking about the world, according to which we can say things like “There are things called planets, and something called the sun, all of which move through something called space, and planets do something called orbiting the sun, and those orbits describe a particular shape in space called an ellipse.” That’s basically Johannes Kepler’s theory of planetary motion, developed after Copernicus argued for the sun being at the center of the solar system but before Isaac Newton explained it all in terms of the force of gravity. Today, we would say that Kepler’s theory is fairly useful in certain circumstances, but it’s not as useful as Newton’s, which in turn isn’t as broadly useful as Einstein’s general theory of relativity.

A poetic naturalist will agree that both Captain Kirk and the Ship of Theseus are simply ways of talking about certain collections of atoms stretching through space and time. The difference is that an eliminativist will say “and therefore they are just illusions,” while the poetic naturalist says “but they are no less real for all of that.”

There are some good things about what Carroll is doing here. He is right of course to insist that the things of common experience are “real.” He is also right to see some relationship between saying that something is real and saying that talking about it is useful, but this is certainly worth additional consideration, and he does not really do it justice.

The problematic part is that, on account of his pre-Socratic tendencies, he is falling somewhat into the error of Parmenides. The error of Parmenides was to suppose that being can be, and can be thought and said, in only one way. Carroll, on account of confusing the various meanings of “fundamental,” supposes that being can be in only one way, namely as something elemental, but that it can be thought and said in many ways.

The problem with this, apart from the falsity of asserting that being can be in only one way, is that no metaphysical account is given whereby it would be reasonable to say that being can be thought and said in many ways, given that it can be in only one way. Carroll is trying to point in that direction by saying that our common speech is useful, so it must be about real things; but the eliminativist would respond, “Useful to whom? The things that you are saying this is useful for are illusions and do not exist. So even your supposed usefulness does not exist.” And Carroll will have no valid response, because he has already admitted to agreeing with the eliminativist on a metaphysical level.

The correct answer to this is the one given by Aristotle. Material causes do not sufficiently explain reality, but other causes are necessary as well. But this means that the eliminativist is mistaken on a metaphysical level, not merely in his way of speaking.

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Science and Certain Theories of Sean Collins

Sean Collins discusses faith and science:

Since at least the time of Descartes, there has come to be a very widespread tendency to see faith as properly the activity of an individual who stands in opposition to a larger, potentially deceptive, world. Faith so conceived is of a piece with individualist notions about the true and the good. At its extreme, the problematic character of faith thus conceived leads some to suppose it can only be an exercise in irrationality. And that is one very common reason why faith, and religion along with it, comes to be  despised.

What needs to be recovered, far away from that extreme, is consciousness of participation as lying at the foundation of all ontology, but in particular at the foundation of what faith is. Faith is knowledge by participation. But what we still tend to have, instead, is an individualist conception even of knowledge itself.

These misconceptions are receding more and more, though, in one very surprising place, namely contemporary science! (It is characteristic of our psychological hypochondria that they recede for us as long as we don’t pay attention to the fact, and thus worry about it.) Everyone uses the expression, “we now know.” “We now know” that our galaxy is but one among many. “We now know” that the blood circulates, and uses hemoglobin to carry oxygen to cells; we now know that there are more than four elements…. One might expect this expression to be disturbing to many people, on account of the contempt for faith I alluded to above; for what the expression refers to is, in fact, a kind of faith within the realm of science. Yet this faith is too manifestly natural for anyone to find it disturbing.  To find it disturbing, one would have to return to the radical neurotic Cartesian individualism, where you sit in a room by yourself and try to deduce all of reality. Most people aren’t devoid of sense enough to do that.

What is especially interesting is that the project of modern science (scientia, knowledge) has itself become obviously too big to continue under the earlier enlightenment paradigm, where we think we must know everything by doing our own experiments and making our own observations. And nobody worries about that fact (at least not as long as “politics,” in the pejorative sense, hasn’t yet entered the picture). Real people understand that there is no reason to worry. They are perfectly content to have faith: that is, to participate in somebody else’s knowledge. An implicit consciousness of a common good in this case makes the individualist conception of faith vanish, and a far truer conception takes its place. This is what real faith — including religious faith — looks like, and it isn’t as different from knowledge or from “reason” as many tend to think.

This is related to our discussion in this previous post, where we pointed out that scientific knowledge has an essential dependence on the work of others, and is not simply a syllogism from first principles that an individual can work out on his own. In this sense, Collins notes, science necessarily involves a kind of faith in the scientific community, past and present, and scientists themselves are not exempt from the need for this faith.

The implication of this is that religious faith should be looked at in much the same way. Religious faith requires faith in a religious community and in revelation from God, and even those in authority in the community are not exempt from the need for this faith. There is no more reason to view this as problematic or irrational than in the case of science.

James Chastek makes a similar argument:

The science of the scientist is, of itself, just as hidden as the God of the priests and consecrated persons. The great majority of persons have no more direct or distinct experience of God than they have a justified insight into scientific claims, and the way in which they could learn the science for themselves if they only had the time and talent is the same way in which they could become preternaturally holy and achieve the unitive way if they only had the time and talent.  If I, lacking the science, trust your testimony about dark matter or global warming (probably after it’s backed up by anecdotes, a gesture at some data, the social pressure to believe, and my sense that you just sound like a smart guy) then I’m in a cognitive state called faith. Taking a pragmatist approach, we come to know the value of science by its fruits in technology just as we know the value of religion though the holiness of the saints. In good logic, Pinker sees the value that many give to holiness as disordered and mistaken,  but there are all sorts of persons who say the same thing about technology.

The similarity between the title of this post and that of the last is not accidental. Dawkins claims that religious beliefs are similar to beliefs in fairies and werewolves, and his claim is empirically false. Likewise Sean Collins and James Chastek claim that religious beliefs are similar to scientific beliefs, and their claim is empirically false.

As in the case of Dawkins, Collins notes from the beginning this empirical discrepancy. Religious faith is seen as “the activity of an individual who stands in opposition to a larger, potentially deceptive, world,” and consequently it appears irrational to many. “And that is one very common reason why faith, and religion along with it, comes to be  despised.” But note that this does not commonly happen with science, even if in principle one could think in the same way about science, as Chastek points to some critics of technology.

While the empirical differences themselves will have their own causes, we can point to one empirical difference in particular that sufficiently explains the different way that people relate to scientific and religious beliefs.

The principle difference is that people speak of “many religions” in the world in a way in which they definitely do not speak of “many sciences.” If we talk of several sciences, we refer to branches of science, and the corresponding speech about religion would be branches of theology. But “many religions” refers to Catholicism, Islam, Judaism, and so on, which contain entirely distinct bodies of theology which are strongly opposed to one another. There is no analog in the case of science. We might be able to find scientific disagreements and even “heresies” like the denial of global warming, but we do not find whole bodies of scientific doctrine about the world which explain the world as a whole and are strongly opposed to one another.

There are many other empirical differences that result from this one difference. People leave their religion and join another, or they give up religion entirely, but you never see people leave their science and join another, or give up science entirely, in the sense of abandoning all scientific beliefs about the world.

This one difference sufficiently explains the suspicion Collins notes regarding religious belief. The size of the discrepancies between religious beliefs implies that many of them are wildly far from reality. And even the religious beliefs that a person might accept are frequently “rather implausible from a relatively neutral point of view,” as Rod Dreher notes. In the case of scientific beliefs, we do find some that are somewhat implausible from a relatively neutral point of view, but we do not find the kind of discrepancy which would force us to say that any of them are wildly far from reality.

A prediction that would follow from my account here would be this: if there were only one religion, in the way that there is only one science, people would not view religion with suspicion, and religious faith would actually be seen as very like scientific faith, basically in the way asserted by Sean Collins.

While we cannot test this prediction directly, consider the following text from St. Augustine:

1. I must express my satisfaction, and congratulations, and admiration, my son Boniface, in that, amid all the cares of wars and arms, you are eagerly anxious to know concerning the things that are of God. From hence it is clear that in you it is actually a part of your military valor to serve in truth the faith which is in Christ. To place, therefore, briefly before your Grace the difference between the errors of the Arians and the Donatists, the Arians say that the Father, the Son, and the Holy Ghost are different in substance; whereas the Donatists do not say this, but acknowledge the unity of substance in the Trinity. And if some even of them have said that the Son was inferior to the Father, yet they have not denied that He is of the same substance; while the greater part of them declare that they hold entirely the same belief regarding the Father and the Son and the Holy Ghost as is held by the Catholic Church. Nor is this the actual question in dispute with them; but they carry on their unhappy strife solely on the question of communion, and in the perversity of their error maintain rebellious hostility against the unity of Christ. But sometimes, as we have heard, some of them, wishing to conciliate the Goths, since they see that they are not without a certain amount of power, profess to entertain the same belief as they. But they are refuted by the authority of their own leaders; for Donatus himself, of whose party they boast themselves to be, is never said to have held this belief.

2. Let not, however, things like these disturb you, my beloved son. For it is foretold to us that there must needs be heresies and stumbling-blocks, that we may be instructed among our enemies; and that so both our faith and our love may be the more approved—our faith, namely, that we should not be deceived by them; and our love, that we should take the utmost pains we can to correct the erring ones themselves; not only watching that they should do no injury to the weak, and that they should be delivered from their wicked error, but also praying for them, that God would open their understanding, and that they might comprehend the Scriptures. For in the sacred books, where the Lord Christ is made manifest, there is also His Church declared; but they, with wondrous blindness, while they would know nothing of Christ Himself save what is revealed in the Scriptures, yet form their notion of His Church from the vanity of human falsehood, instead of learning what it is on the authority of the sacred books.

3. They recognize Christ together with us in that which is written, “They pierced my hands and my feet. They can tell all my bones: they look and stare upon me. They part my garments among them, and cast lots upon my vesture;” and yet they refuse to recognize the Church in that which follows shortly after: “All the ends of the world shall remember, and turn unto the Lord; and all the kindreds of the nations shall worship before You. For the kingdom is the Lord’s; and He is the Governor among the nations.” They recognize Christ together with us in that which is written, “The Lord has said unto me, You are my Son, this day have I begotten You;” and they will not recognize the Church in that which follows: “Ask of me, and I shall give You the heathen for Your inheritance, and the uttermost parts of the earth for Your possession.” They recognize Christ together with us in that which the Lord Himself says in the gospel, “Thus it behooved Christ to suffer, and to rise from the dead the third day;” and they will not recognize the Church in that which follows: “And that repentance and remission of sins should be preached in His name among all nations, beginning at Jerusalem.” Luke 24:46-47 And the testimonies in the sacred books are without number, all of which it has not been necessary for me to crowd together into this book. And in all of them, as the Lord Christ is made manifest, whether in accordance with His Godhead, in which He is equal to the Father, so that, “In the beginning was the Word, and; the Word was with God, and the Word was God;” or according to the humility of the flesh which He took upon Him, whereby “the Word was made flesh and dwelt among us;” so is His Church made manifest, not in Africa alone, as they most impudently venture in the madness of their vanity to assert, but spread abroad throughout the world.

4. For they prefer to the testimonies of Holy Writ their own contentions, because, in the case of Cæcilianus, formerly a bishop of the Church of Carthage, against whom they brought charges which they were and are unable to substantiate, they separated themselves from the Catholic Church—that is, from the unity of all nations. Although, even if the charges had been true which were brought by them against Cæcilianus, and could at length be proved to us, yet, though we might pronounce an anathema upon him even in the grave, we are still bound not for the sake of any man to leave the Church, which rests for its foundation on divine witness, and is not the figment of litigious opinions, seeing that it is better to trust in the Lord than to put confidence in man. For we cannot allow that if Cæcilianus had erred,— a supposition which I make without prejudice to his integrity—Christ should therefore have forfeited His inheritance. It is easy for a man to believe of his fellow-men either what is true or what is false; but it marks abandoned impudence to desire to condemn the communion of the whole world on account of charges alleged against a man, of which you cannot establish the truth in the face of the world.

5. Whether Cæcilianus was ordained by men who had delivered up the sacred books, I do not know. I did not see it, I heard it only from his enemies. It is not declared to me in the law of God, or in the utterances of the prophets, or in the holy poetry of the Psalms, or in the writings of any one of Christ’s apostles, or in the eloquence of Christ Himself. But the evidence of all the several scriptures with one accord proclaims the Church spread abroad throughout the world, with which the faction of Donatus does not hold communion. The law of God declared, “In your seed shall all the nations of the earth be blessed.” Genesis 26:4 The Lord said by the mouth of His prophet, “From the rising of the sun, even unto the going down of the same, a pure sacrifice shall be offered unto my name: for my name shall be great among the heathen.” Malachi 1:11 The Lord said through the Psalmist, “He shall have dominion also from sea to sea, and from the river unto the ends of the earth.” The Lord said by His apostle, “The gospel has come unto you, as it is in all the world, and brings forth fruit.” Colossians 1:6 The Son of God said with His own mouth, “You shall be witnesses unto me, both in Jerusalem, and in all Judea, and in Samaria, and even unto the uttermost part of the earth.” Acts 1:8 Cæcilianus, the bishop of the Church of Carthage, is accused with the contentiousness of men; the Church of Christ, established among all nations, is recommended by the voice of God. Mere piety, truth, and love forbid us to receive against Cæcilianus the testimony of men whom we do not find in the Church, which has the testimony of God; for those who do not follow the testimony of God have forfeited the weight which otherwise would attach to their testimony as men.

Note the source of St. Augustine’s confidence. It is the “unity of the whole world.” It is “abandoned impudence to desire to condemn the communion of the whole world.” The Catholic Church is “established among all nations,” and this is reason to accept it instead of the doctrines of the heretics.

The comparison between religious beliefs and scientific beliefs applies much better to the time of St. Augustine. Even St. Augustine would know that alternate religions exist, but in a similar sense there might have appeared to be potentially many sciences, insofar as science is not at the time a unified body of ideas attempting to explain the world. Thales held that all things are derived from water, while others came out in favor of air or fire.

Nonetheless, even at the time of St. Augustine, there are seeds of the difference. Unknown to St. Augustine, native Americans of the time were certainly practicing entirely different religions. And while I made the comparison between religious heresy and dissent on certain scientific questions above, these in practice have their own differences. Religious heresy of itself contains a seed of schism, and thus the possibility of establishing a new religion. Scientific disagreement even of the kind that might be compared with “heresy,” never leads to the development of a new set of scientific doctrines about the world that can be considered an alternative science.

In contrast, if even religious heresy had not existed, St. Augustine would be entirely right simply to point to the consent of the world. Aristotle frequently points to the agreement of all men as one of the best signs of truth, for example here:

And about all these matters the endeavor must be made to seek to convince by means of rational arguments, using observed facts as evidences and examples. For the best thing would be if all mankind were seen to be in agreement with the views that will be stated, but failing that, at any rate that all should agree in some way. And this they will do if led to change their ground, for everyone has something relative to contribute to the truth, and we must start from this to give a sort of proof about our views; for from statements that are true but not clearly expressed, as we advance, clearness will also be attained, if at every stage we adopt more scientific positions in exchange for the customary confused statements.

And indeed, if there were in this way one religion with which all were in agreement, it is not merely that they would agree in fact, since this is posited, but the agreement of each would have an extremely reasonable foundation. In this situation, it would be quite reasonable to speak of religious faith and scientific faith as roughly equivalent.

In the real world, however, religious beliefs are neither like beliefs in fairies and unicorns, nor like scientific beliefs.

But as Aristotle says, “everyone has something relative to contribute to the truth,” and just as we saw some true elements in Dawkins’s point in the previous post, so there is some truth to the comparisons made by Collins and Chastek. This is in fact part of the reason why Dawkins’s basic point is mistaken. He fails to consider religious belief as a way of participating in a community, and thus does not see a difference from beliefs in werewolves and the like.

Not All Things are Water

The basic point of the post on Thales was that material things are composed of one or more material elements. The ancient materialists were accustomed not only to maintain this position, but also to assert that it also followed that there was nothing but those elements. Thus Democritus is said to have said,

By convention, sweet; by convention, bitter; by convention, hot; by convention,
cold; by convention, color; but in reality, atoms and void.

One could say that this is an example of the attitude of “this or nothing.” If everything is made of atoms, then either a thing is atoms, or it is nothing.

The correct answer here is not to say “this or that,” but “this and that,” that is, that things made of atoms are in some way atoms, but they are also things made of them, and the things made of them are not merely atoms.

 

All Things are Water

In book I of his Metaphysics, Aristotle comments on earlier opinions about the first causes:

Evidently we have to acquire knowledge of the original causes (for we say we know each thing only when we think we recognize its first cause), and causes are spoken of in four senses. In one of these we mean the substance, i.e. the essence (for the ‘why’ is reducible finally to the definition, and the ultimate ‘why’ is a cause and principle); in another the matter or substratum, in a third the source of the change, and in a fourth the cause opposed to this, the purpose and the good (for this is the end of all generation and change). We have studied these causes sufficiently in our work on nature, but yet let us call to our aid those who have attacked the investigation of being and philosophized about reality before us. For obviously they too speak of certain principles and causes; to go over their views, then, will be of profit to the present inquiry, for we shall either find another kind of cause, or be more convinced of the correctness of those which we now maintain.

Of the first philosophers, then, most thought the principles which were of the nature of matter were the only principles of all things. That of which all things that are consist, the first from which they come to be, the last into which they are resolved (the substance remaining, but changing in its modifications), this they say is the element and this the principle of things, and therefore they think nothing is either generated or destroyed, since this sort of entity is always conserved, as we say Socrates neither comes to be absolutely when he comes to be beautiful or musical, nor ceases to be when loses these characteristics, because the substratum, Socrates himself remains. just so they say nothing else comes to be or ceases to be; for there must be some entity-either one or more than one-from which all other things come to be, it being conserved.

Yet they do not all agree as to the number and the nature of these principles. Thales, the founder of this type of philosophy, says the principle is water (for which reason he declared that the earth rests on water), getting the notion perhaps from seeing that the nutriment of all things is moist, and that heat itself is generated from the moist and kept alive by it (and that from which they come to be is a principle of all things). He got his notion from this fact, and from the fact that the seeds of all things have a moist nature, and that water is the origin of the nature of moist things.

Some think that even the ancients who lived long before the present generation, and first framed accounts of the gods, had a similar view of nature; for they made Ocean and Tethys the parents of creation, and described the oath of the gods as being by water, to which they give the name of Styx; for what is oldest is most honourable, and the most honourable thing is that by which one swears. It may perhaps be uncertain whether this opinion about nature is primitive and ancient, but Thales at any rate is said to have declared himself thus about the first cause.

It is possibly for polemical motives that Aristotle portrays Thales as asserting that water alone is the principle of all things, to the exclusion of other kinds of cause besides the material cause. That is, most materialists, ancient and modern, do not believe that matter is the sole principle of reality. They may think it is the most important principle, but they recognize that other principles are involved, much as Lucretius recognizes that his atoms alone are insufficient to explain the world, but he must add something:

We wish thee also well aware of this:
The atoms, as their own weight bears them down
Plumb through the void, at scarce determined times,
In scarce determined places, from their course
Decline a little- call it, so to speak,
Mere changed trend. For were it not their wont
Thuswise to swerve, down would they fall, each one,
Like drops of rain, through the unbottomed void;
And then collisions ne’er could be nor blows
Among the primal elements; and thus
Nature would never have created aught.

We can understand however that even if Aristotle’s account may not be a completely accurate account of Thales’s opinions, Aristotle likely has a charitable motive for his presentation, namely the education of the reader, as by beginning by discussing the position that matter alone is the first cause, it becomes easier to see the necessity of other principles. And it is also possible that Thales did not mention any other principles simply because his interest was in the material principle, rather than from the wish to deny other principles.

There is some probability to the opinion, mentioned by Aristotle, that Thales’s idea about water had ancient predecessors. For example, there may be something like this in Genesis 1:

In the beginning when God created the heavens and the earth, the earth was a formless void and darkness covered the face of the deep, while a wind from God swept over the face of the waters. Then God said, “Let there be light”; and there was light. And God saw that the light was good; and God separated the light from the darkness. God called the light Day, and the darkness he called Night. And there was evening and there was morning, the first day.

And God said, “Let there be a dome in the midst of the waters, and let it separate the waters from the waters.” So God made the dome and separated the waters that were under the dome from the waters that were above the dome. And it was so. God called the dome Sky. And there was evening and there was morning, the second day.

And God said, “Let the waters under the sky be gathered together into one place, and let the dry land appear.” And it was so. God called the dry land Earth, and the waters that were gathered together he called Seas. And God saw that it was good.

The text speaks of a number of principles, including God, and formless matter. But the formless matter is virtually identified with water; even when the earth is a “formless void,” there is still a “deep”, and there is still a “face of the waters.” And God makes the world by divisions in the waters, creating first sky and world, and then creating dry land by limiting the lower waters.

We can ask whether Thales was right in several different ways:

First, was he right if he is understood as Aristotle understands him? In this way, his position would involve denying all principles other than material principles. And in this way Thales was wrong, since there are other principles.

Second, was he right if he is understood in contrast with other materialist philosophers such as Anaximenes, who said that all things are made of air? We can see that there is a certain difficulty in such a supposition from the beginning. For if there is only one material principle of all things, why call it “water” or “air” in particular? If water contains nothing but the first material principle, and air contains nothing but the first material principle, why is one of them identified with the principle rather than the other?

Nonetheless, we can understand the claim to be something like, “Water is the most basic and natural form of the first material principle.” In this case, what it means to be the most basic and natural would be a matter of investigation, but there is nothing impossible about it in principle. But if we understand it in this way, Thales’s position (along with that of Anaximenes and others) is refuted by modern science, since water is known to be made of other more basic things, namely oxygen and hydrogen.

But we can ask whether Thales and Anaximenes were both right in a third way, a more generic way. If we break composite material things down into their parts, and their parts into their parts, and so on, will we always arrive at one basic material “stuff” which all other things are made out of?

This would necessarily be different from the prime matter of Aristotle, because this matter is understood to be completely formless. So while it may be part of a substance along with substantial form, it is not a part in the way that an arm is a part of a human being, or in the way that oxygen is part of water. A part in the latter sense already has some actuality; an arm has a certain shape even apart from being a part of a human being, and oxygen has qualities that it has even apart from water, while prime matter has no actuality whatsoever.

Since every order of causes comes to a first cause, the same will be true if we follow the order of material causality found by asking, “What parts is this made out of?” This cannot be refuted even if it turns out that material things are infinitely divisible, because it will not actually be true that anything is made out of an infinite number of parts. If we say, “this is made out of two halves, and the halves out of more halves, and so on,” this is not an explanation at all, as was pointed out in the post linked above, and so it cannot be a true account of why the thing is as it is. It may be that the thing is potentially divisible in those ways; but it is not actually made out of those parts. Instead, we are asking what we will arrive at if we look at the material composition of things, looking only for things with some actuality, and stopping when we find something which is not made up of other things in this way.

We made a strong argument that there only one first efficient cause. But we cannot duplicate that argument to show that there must be only one first material part of things, since the first efficient cause could be an adequate explanation of two or more first material causes. The theory of the four (or five) elements is an explanation like this. The first material parts are thought be four or five, according to this account, and in this way Thales would have been mistaken.

We can see some motivation for holding such a position. If there is fundamentally only one kind of “stuff,” why do we see various things in the world, such as plants and animals, rocks, chairs, and people? An account with a number elements can say that they form various things by being combined in various proportions and ways, while it is not evident how this question can be answered, if there is only one element.

Nonetheless, this does not really refute the position that there is fundamentally a single material element. If that element can exist in various ways, then it would be possible to explain how it could be used to form more complex substances. It is true that this would still leave something to be explained, namely the nature of those various ways that the element can exist, and how and why they come to be.

The position is neither refuted nor established by modern science. The Standard Model of particle physics contains many elementary particles, but in any case it is not thought to be a complete theory of physics.

Considerations of simplicity would favor the position of Thales. Other things being equal, it should be thought that a theory with a single element is more likely than one with ten elements; one with ten more likely than one with a hundred, and so on. Nonetheless, there does not seem to be any proof of Thales’s general position, nor any refutation of it. But one way or another, there will be one or more simplest material parts that everything else is made out of.