Minimizing Motivated Beliefs

In the last post, we noted that there is a conflict between the goal of accurate beliefs about your future actions, and your own goals about your future. More accurate beliefs will not always lead to a better fulfillment of those goals. This implies that you must be ready to engage in a certain amount of trade, if you desire both truth and other things. Eliezer Yudkowsky argues that self-deception, and therefore also such trade, is either impossible or stupid, depending on how it is understood:

What if self-deception helps us be happy?  What if just running out and overcoming bias will make us—gasp!—unhappy?  Surely, true wisdom would be second-order rationality, choosing when to be rational.  That way you can decide which cognitive biases should govern you, to maximize your happiness.

Leaving the morality aside, I doubt such a lunatic dislocation in the mind could really happen.

Second-order rationality implies that at some point, you will think to yourself, “And now, I will irrationally believe that I will win the lottery, in order to make myself happy.”  But we do not have such direct control over our beliefs.  You cannot make yourself believe the sky is green by an act of will.  You might be able to believe you believed it—though I have just made that more difficult for you by pointing out the difference.  (You’re welcome!)  You might even believe you were happy and self-deceived; but you would not in fact be happy and self-deceived.

For second-order rationality to be genuinely rational, you would first need a good model of reality, to extrapolate the consequences of rationality and irrationality.  If you then chose to be first-order irrational, you would need to forget this accurate view. And then forget the act of forgetting.  I don’t mean to commit the logical fallacy of generalizing from fictional evidence, but I think Orwell did a good job of extrapolating where this path leads.

You can’t know the consequences of being biased, until you have already debiased yourself.  And then it is too late for self-deception.

The other alternative is to choose blindly to remain biased, without any clear idea of the consequences.  This is not second-order rationality.  It is willful stupidity.

There are several errors here. The first is the denial that belief is voluntary. As I remarked in the comments to this post, it is best to think of “choosing to believe a thing” as “choosing to treat this thing as a fact.” And this is something which is indeed voluntary. Thus for example it is by choice that I am, at this very moment, treating it as a fact that belief is voluntary.

There is some truth in Yudkowsky’s remark that “you cannot make yourself believe the sky is green by an act of will.” But this is not because the thing itself is intrinsically involuntary. On the contrary, you could, if you wished, choose to treat the greenness of the sky as a fact, at least for the most part and in most ways. The problem is that you have no good motive to wish to act this way, and plenty of good motives not to act this way. In this sense, it is impossible for most of us to believe that the sky is green in the same way it is impossible for most of us to commit suicide; we simply have no good motive to do either of these things.

Yudkowsky’s second error is connected with the first. Since, according to him, it is impossible to deliberately and directly deceive oneself, self-deception can only happen in an indirect manner: “The other alternative is to choose blindly to remain biased, without any clear idea of the consequences.  This is not second-order rationality.  It is willful stupidity.” The idea is that ordinary beliefs are simply involuntary, but we can have beliefs that are somewhat voluntary by choosing “blindly to remain biased, without any clear idea of the consequences.” Since this is “willful stupidity,” a reasonable person would completely avoid such behavior, and thus all of his beliefs would be involuntary.

Essentially, Yudkowsky is claiming that we have some involuntary beliefs, and that we should avoid adding any voluntary beliefs to our involuntary ones. This view is fundamentally flawed precisely because all of our beliefs are voluntary, and thus we cannot avoid having voluntary beliefs.

Nor is it “willful stupidity” to trade away some truth for the sake of other good things. Completely avoiding this is in fact intrinsically impossible. If you are seeking one good, you are not equally seeking a distinct good; one cannot serve two masters. Thus since all people are interested in some goods distinct from truth, there is no one who fails to trade away some truth for the sake of other things. Yudkowsky’s mistake here is related to his wishful thinking about wishful thinking which I discussed previously. In this way he views himself, at least ideally, as completely avoiding wishful thinking. This is both impossible and unhelpful, impossible in that everyone has such motivated beliefs, and unhelpful because such beliefs can in fact be beneficial.

A better attitude to this matter is adopted by Robin Hanson, as for example when he discusses motives for having opinions in a post which we previously considered here. Bryan Caplan has a similar view, discussed here.

Once we have a clear view of this matter, we can use this to minimize the loss of truth that results from such beliefs. For example, in a post linked above, we discussed the argument that fictional accounts consistently distort one’s beliefs about reality. Rather than pretending that there is no such effect, we can deliberately consider to what extent we wish to be open to this possibility, depending on our other purposes for engaging with such accounts. This is not “willful stupidity”; the stupidity would to be engage in such trades without realizing that such trades are inevitable, and thus not to realize to what extent you are doing it.

Consider one of the cases of voluntary belief discussed in this earlier post. As we quoted at the time, Eric Reitan remarks:

For most horror victims, the sense that their lives have positive meaning may depend on the conviction that a transcendent good is at work redeeming evil. Is the evidential case against the existence of such a good really so convincing that it warrants saying to these horror victims, “Give up hope”? Should we call them irrational when they cling to that hope or when those among the privileged live in that hope for the sake of the afflicted? What does moral decency imply about the legitimacy of insisting, as the new atheists do, that any view of life which embraces the ethico-religious hope should be expunged from the world?

Here, Reitan is proposing that someone believe that “a transcendent good is at work redeeming evil” for the purpose of having “the sense that their lives have positive meaning.” If we look at this as it is, namely as proposing a voluntary belief for the sake of something other than truth, we can find ways to minimize the potential conflict between accuracy and this other goal. For example, the person might simply believe that “my life has a positive meaning,” without trying to explain why this is so. For the reasons given here, “my life has a positive meaning” is necessarily more probable and more known than any explanation for this that might be adopted. To pick a particular explanation and claim that it is more likely would be to fall into the conjunction fallacy.

Of course, real life is unfortunately more complicated. The woman in Reitan’s discussion might well respond to our proposal somewhat in this way (not a real quotation):

Probability is not the issue here, precisely because it is not a question of the truth of the matter in itself. There is a need to actually feel that one’s life is meaningful, not just to believe it. And the simple statement “life is meaningful” will not provide that feeling. Without the feeling, it will also be almost impossible to continue to believe it, no matter what the probability is. So in order to achieve this goal, it is necessary to believe a stronger and more particular claim.

And this response might be correct. Some such goals, due to their complexity, might not be easily achieved without adopting rather unlikely beliefs. For example, Robin Hanson, while discussing his reasons for having opinions, several times mentions the desire for “interesting” opinions. This is a case where many people will not even notice the trade involved, because the desire for interesting ideas seems closely related to the desire for truth. But in fact truth and interestingness are diverse things, and the goals are diverse, and one who desires both will likely engage in some trade. In fact, relative to truth seeking, looking for interesting things is a dangerous endeavor. Scott Alexander notes that interesting things are usually false:

This suggests a more general principle: interesting things should usually be lies. Let me give three examples.

I wrote in Toxoplasma of Rage about how even when people crusade against real evils, the particular stories they focus on tend to be false disproportionately often. Why? Because the thousands of true stories all have some subtleties or complicating factors, whereas liars are free to make up things which exactly perfectly fit the narrative. Given thousands of stories to choose from, the ones that bubble to the top will probably be the lies, just like on Reddit.

Every time I do a links post, even when I am very careful to double- and triple- check everything, and to only link to trustworthy sources in the mainstream media, a couple of my links end up being wrong. I’m selecting for surprising-if-true stories, but there’s only one way to get surprising-if-true stories that isn’t surprising, and given an entire Internet to choose from, many of the stories involved will be false.

And then there’s bad science. I can’t remember where I first saw this, so I can’t give credit, but somebody argued that the problem with non-replicable science isn’t just publication bias or p-hacking. It’s that some people will be sloppy, biased, or just stumble through bad luck upon a seemingly-good methodology that actually produces lots of false positives, and that almost all interesting results will come from these people. They’re the equivalent of Reddit liars – if there are enough of them, then all of the top comments will be theirs, since they’re able to come up with much more interesting stuff than the truth-tellers. In fields where sloppiness is easy, the truth-tellers will be gradually driven out, appearing to be incompetent since they can’t even replicate the most basic findings of the field, let alone advance it in any way. The sloppy people will survive to train the next generation of PhD students, and you’ll end up with a stable equilibrium.

In a way this makes the goal of believing interesting things much like the woman’s case. The goal of “believing interesting things” will be better achieved by more complex and detailed beliefs, even though to the extent that they are more complex and detailed, they are simply that much less likely to be true.

The point of this present post, then, is not to deny that some goals might be such that they are better attained with rather unlikely beliefs, and in some cases even in proportion to the unlikelihood of the beliefs. Rather, the point is that a conscious awareness of the trades involved will allow a person to minimize the loss of truth involved. If you never look at your bank account, you will not notice how much money you are losing from that monthly debit for internet. In the same way, if you hold Yudkowksy’s opinion, and believe that you never trade away truth for other things, which is itself both false and motivated, you are like someone who never looks at your account: you will not notice how much you are losing.


Self-Fulfilling Prophecy

We can formulate a number of objections to the thesis argued in the previous post.

First, if a belief that one is going to do something is the same as the decision to do it, another person’s belief that I am going to do something should mean that the other person is making a decision for me. But this is absurd.

Second, suppose that I know that I am going to be hit on the head and suffer from amnesia, thus forgetting all about these considerations. I may believe that I will eat breakfast tomorrow, but this is surely not a decision to do so.

Third, suppose someone wants to give up smoking. He may firmly hold the opinion that whatever he does, he will sometimes smoke within the next six months, not because he wants to do so, but because he does not believe it possible that he do otherwise. We would not want to say that he decided not to give up smoking.

Fourth, decisions are appropriate objects of praise and blame. We seem at least somewhat more reluctant to praise and blame beliefs, even if it is sometimes done.

Fifth, suppose someone believes, “I will kill Peter tomorrow at 4:30 PM.” We will wish to blame him for deciding to kill Peter. But if he does kill Peter tomorrow at 4:30, he held a true belief. Even if beliefs can be praised or blamed, it seems implausible that a true belief should be blamed.

The objections are helpful. With their aid we can see that there is indeed a flaw in the original proposal, but that it is nonetheless somewhat on the right track. A more accurate proposal would be this: a decision is a voluntary self-fulfilling prophecy as understood by the decision maker. I will explain as we consider the above arguments in more detail.

In the first argument, in the case of one person making a decision for another, the problem is that a mere belief that someone else is going to do something is not self-fulfilling. If I hold a belief that I myself will do something, the belief will tend to cause its own truth, just as suggested in the previous post. But believing that someone else will do something will not in general cause that person to do anything. Consider the following situation: a father says to his children as he departs for the day, “I am quite sure that the house will be clean when I get home.” If the children clean the house during his absence, suddenly it is much less obvious that we should deny that this was the father’s decision. In fact, the only reason this is not truly the father’s decision, without any qualification at all, is that it does not sufficiently possess the characteristics of a self-fulfilling prophecy. First, in the example it does not seem to matter whether the father believes what he says, but only whether he says it. Second, since it is in the power of the children to fail to clean the house in any case, there seems to be a lack of sufficient causal connection between the statement and the cleaning of the house. Suppose belief did matter, namely suppose that the children will know whether he believes what he says or not. And suppose additionally that his belief had an infallible power to make his children clean the house. In that case it would be quite reasonable to say, without any qualification, “He decided that his children would clean the house during his absence.” Likewise, even if the father falsely believes that he has such an infallible power, in a sense we could rightly describe him as trying to make that decision, just as we might say, “I decided to open the door,” even if it turns out that my belief that the door could be opened turns out to be false when I try it; the door may be locked. This is why I included the clause “as understood by the decision maker” in the above proposal. This is a typical character of moral analysis; human action must be understood from the perspective of the one who acts.

In the amnesia case, there is a similar problem: due to the amnesia, the person’s current beliefs do not have a causal connection with his later actions. In addition, if we consider such things as “eating breakfast,” there might be a certain lack of causal connection in any case; the person would likely eat breakfast whether or not he formulates any opinion about what he will do. And to this degree we might feel it implausible to say that his belief that he will eat breakfast is a decision, even without the amnesia. It is not understood by the subject as a self-fulfilling prophecy.

In the case of giving up smoking, there are several problems. In this case, the subject does not believe that there is any causal connection between his beliefs and his actions. Regardless of what he believes, he thinks, he is going to smoke in fact. Thus, in his opinion, if he believes that he will stop smoking completely, he will simply hold a false belief without getting any benefit from it; he will still smoke, and his belief will just be false. So since the belief is false, and without benefit, at least as he understands it, there is no reason for him to hold this belief. Consequently, he holds the opposite belief. But this is not a decision, since he does not understand it as causing his smoking, which is something that is expected to happen whether or not he believes it will.

In such cases in real life, we are in fact sometimes tempted to say that the person is choosing not to give up smoking. And we are tempted to this to the extent that it seems to us that his belief should have the causal power that he denies it has: his denial seems to stem from the desire to smoke. If he wanted to give up smoking, we think, he could just accept that he would be able to believe this, and in such a way that it would come true. He does not, we think, because he wants to smoke, and so does not want to give up smoking. In reality this is a question of degree, and this analysis can have some truth. Consider the following from St. Augustine’s Confessions (Book VIII, Ch. 7-8):

Finally, in the very fever of my indecision, I made many motions with my body; like men do when they will to act but cannot, either because they do not have the limbs or because their limbs are bound or weakened by disease, or incapacitated in some other way. Thus if I tore my hair, struck my forehead, or, entwining my fingers, clasped my knee, these I did because I willed it. But I might have willed it and still not have done it, if the nerves had not obeyed my will. Many things then I did, in which the will and power to do were not the same. Yet I did not do that one thing which seemed to me infinitely more desirable, which before long I should have power to will because shortly when I willed, I would will with a single will. For in this, the power of willing is the power of doing; and as yet I could not do it. Thus my body more readily obeyed the slightest wish of the soul in moving its limbs at the order of my mind than my soul obeyed itself to accomplish in the will alone its great resolve.

How can there be such a strange anomaly? And why is it? Let thy mercy shine on me, that I may inquire and find an answer, amid the dark labyrinth of human punishment and in the darkest contritions of the sons of Adam. Whence such an anomaly? And why should it be? The mind commands the body, and the body obeys. The mind commands itself and is resisted. The mind commands the hand to be moved and there is such readiness that the command is scarcely distinguished from the obedience in act. Yet the mind is mind, and the hand is body. The mind commands the mind to will, and yet though it be itself it does not obey itself. Whence this strange anomaly and why should it be? I repeat: The will commands itself to will, and could not give the command unless it wills; yet what is commanded is not done. But actually the will does not will entirely; therefore it does not command entirely. For as far as it wills, it commands. And as far as it does not will, the thing commanded is not done. For the will commands that there be an act of will–not another, but itself. But it does not command entirely. Therefore, what is commanded does not happen; for if the will were whole and entire, it would not even command it to be, because it would already be. It is, therefore, no strange anomaly partly to will and partly to be unwilling. This is actually an infirmity of mind, which cannot wholly rise, while pressed down by habit, even though it is supported by the truth. And so there are two wills, because one of them is not whole, and what is present in this one is lacking in the other.

St. Augustine analyzes this in the sense that he did not “will entirely” or “command entirely.” If we analyze it in our terms, he does not expect in fact to carry out his intention, because he does not want to, and he knows that people do not do things they do not want to do. In a similar way, in some cases the smoker does not fully want to give up smoking, and therefore believes himself incapable of simply deciding to give up smoking, because if he made that decision, it would happen, and he would not want it to happen.

In the previous post, I mentioned an “obvious objection” at several points. This was that the account as presented there leaves out the role of desire. Suppose someone believes that he will go to Vienna in fact, but does not wish to go there. Then when the time comes to buy a ticket, it is very plausible that he will not buy one. Yes, this will mean that he will stop believing that he will go to Vienna. But this is different from the case where a person has “decided” to go and then changes his mind. The person who does not want to go, is not changing his mind at all, except about the factual question. It seems absurd (and it is) to characterize a decision without any reference to what the person wants.

This is why we have characterized a decision here as “voluntary”, “self-fulfilling,” and “as understood by the decision maker.” It is indeed the case that the person holds a belief, but he holds it because he wants to, and because he expects it to cause its own fulfillment, and he desires that fulfillment.

Consider the analysis in the previous post of the road to point C. Why is it reasonable for anyone, whether the subject or a third party, to conclude that the person will take road A? This is because we know that the subject wishes to get to point C. It is his desire to get to point C that will cause him to take road A, once he understands that A is the only way to get there.

Someone might respond that in this case we could characterize the decision as just a desire: the desire to get to point C. The problem is that the example is overly simplified compared to real life. Ordinarily there is not simply a single way to reach our goals. And the desire to reach the goal may not determine which particular way we take, so something else must determine it. This is precisely why we need to make decisions at all. We could in fact avoid almost anything that feels like a decision, waiting until something else determined the matter, but if we did, we would live very badly indeed.

When we make a complicated plan, there are two interrelated factors explaining why we believe it to be factually true that we will carry out the plan. We know that we desire the goal, and we expect this desire for the goal to move us along the path towards the goal. But since we also have other desires, and there are various paths towards the goal, some better than others, there are many ways that we could go astray before reaching the goal, either by taking a path to some other goal, or by taking a path less suited to the goal. So we also expect the details of our plan to keep us on the particular course that we have planned, which we suppose to be the best, or at least the best path considering our situation as a whole. If we did not keep those details in mind, we would not likely remain on this precise path. As an example, I might plan to stop at a grocery store on my way home from work, out of the desire to possess a sufficient stock of groceries, but if I do not keep the plan in mind, my desire to get home may cause me to go past the store without stopping. Again, this is why our explanation of belief is that it is a self-fulfilling prophecy, and one explicitly understood by the subject as such; by saying “I will use A, B, and C, to get to goal Z,” we expect that keeping these details in mind, together with our desire for Z, we will be moved along this precise path, and we wish to follow this path, for the sake of Z.

There is a lot more that could be said about this. For example, it is not difficult to see here an explanation for the fact that such complicated plans rarely work out precisely in practice, even in the absence of external impediments. We expect our desire for the goal to keep us on track, but in fact we have other desires, and there are an indefinite number of possibilities for those other desires to make something else happen. Likewise, even if the plan was the best we could work out in advance, there will be numberless details in which there were better options that we did not notice while planning, and we will notice some of these as we proceed along the path. So both the desire for the goal, and the desire for other things, will likely derail the plan. And, of course, most plans will be derailed by external things as well.

A combination of the above factors has the result that I will leave the consideration of the fourth and fifth arguments to another post, even though this was not my original intention, and was not my belief about what would happen.

Being and Good

St. Thomas argues that being and goodness are actually the same thing, simply considered in different ways:

Goodness and being are really the same, and differ only in idea; which is clear from the following argument. The essence of goodness consists in this, that it is in some way desirable. Hence the Philosopher says (Ethic. i): “Goodness is what all desire.” Now it is clear that a thing is desirable only in so far as it is perfect; for all desire their own perfection. But everything is perfect so far as it is actual. Therefore it is clear that a thing is perfect so far as it exists; for it is existence that makes all things actual, as is clear from the foregoing (I:3:4; I:4:1). Hence it is clear that goodness and being are the same really. But goodness presents the aspect of desirableness, which being does not present.

We pointed out in the last post that the formal element of desire is the tendency to something. But it is easy to see that existing things tend to exist and to continue to exist, although they do not always succeed in continuing. So in this way existence implies the desire to exist, and the natural explanation for this desire is that existence as such is good, as St. Thomas says here.

Someone might say that this refutes our earlier argument against Richard Dawkins. If being as such a good, then life is necessarily good, and could not have been bad, while we suggested there that the idea was not intrinsically absurd.

However, this refutation fails, for a number of reasons.

First, one might argue that it makes the argument unnecessary, but the basic point is that the universe is not “at bottom” indifferent. And if being as such is good, then in fact the universe is at bottom good, without any qualification.

Second, one of the points in the earlier argument is that in terms of experience life could have been much worse than it is, or at least much more “indifferent” than it is, and this fact is not refuted by the present argument.

Third, the point of saying that as far as we can tell, things could have been different, was that there is something needing explanation. Once you have explained it, it is perfectly possible that you will show that things in fact could not have been different. It is in fact the case that life is necessarily good, but that is precisely because the universe and its cause “at bottom” is not only good but necessarily good.

Every Agent Acts for an End

St. Thomas states in many places that every agent acts for an end. At times he appears to take this as evident, but he also argues for it directly:

I answer that, Every agent, of necessity, acts for an end. For if, in a number of causes ordained to one another, the first be removed, the others must, of necessity, be removed also. Now the first of all causes is the final cause. The reason of which is that matter does not receive form, save in so far as it is moved by an agent; for nothing reduces itself from potentiality to act. But an agent does not move except out of intention for an end. For if the agent were not determinate to some particular effect, it would not do one thing rather than another: consequently in order that it produce a determinate effect, it must, of necessity, be determined to some certain one, which has the nature of an end. And just as this determination is effected, in the rational nature, by the “rational appetite,” which is called the will; so, in other things, it is caused by their natural inclination, which is called the “natural appetite.”

Basically his argument is that an agent is doing something, and there must be some explanation for why it is doing what it is doing, rather than something else. And a final cause is nothing but such an explanation.

Now someone might object that a final cause is this sense is more general than acting for an end, and certainly more general than desiring an end. For example, logical necessity may be a final cause in this sense. Thus if we ask why I walk, rather than both walking and not walking at the same time and in the same way, the logical impossibility of the latter is a sufficient explanation. Or again, if we ask why a very intelligent person does not win at Tic-tac-toe against a relatively unintelligent one, but instead ties, the fact that there are strategies in the game that cannot be defeated, and that are well known even to unintelligent persons, is a sufficient explanation. Far from implying desire, such explanations may be contrary to desire: the person may desire to win the game, but cannot do so.

According to this objection, the fact that a rock falls may have some explanation, but there is no reason to think that the explanation would be that it desires to fall or to be at the center, or that it has any kind of desires at all.

The answer to this is that we must distinguish between what is material in desire, and what is formal. The fact that desires are something that we feel is material in them, and is not why we call them desires. As noted in the linked post, it is not from the sensible experience that we know our desires are desires rather than some other kind of feeling, but from the fact that when we have them, we tend to do certain things. Thus, the feeling is material in desire, while the tendency to do something is formal. Now in the case of the rock, there are no strong reasons for supposing that they have any feelings, and thus for supposing that they have what is material in desire. But it is evident that they have a tendency to do something, and this is what is formal in desire, and constitutes the real reason for saying that something is a desire rather than something else.

It is correct, then, to say that St. Thomas’s universal claim is an analogous extension of the ideas of desire and of intending an end. Nonetheless, it is a perfectly reasonable one and conforms precisely with the formal meaning of these terms.


Will and Experience

Just as we learn the nature of desire from experience, so we also learn from experience the effectiveness of some desires. Thus for example if I want to move my hand, I move my hand. On the other hand, if I want the lamp on my desk to pass to the other side of the room, it does not do so in the way that my hand moves when I want that to happen. Or if I am inside the house and want to be outside, I do not simply pass through the walls, but I need to perform a particular series of actions such as walking to the door and opening it.

All of these are simple facts about the world that we learn from experience, long before any philosophical reflection. But they are facts about the way the world works, not self evident consequences of the nature of our will or desire. I cannot rearrange the stars simply by willing it, but there is no reason in principle why I would find it strange if I could; it is merely a fact of experience that moving the stars is not in my power.

Likewise, there are some things where I do have some immediate ability to do what I wish, but not a perfect ability. For example, I can choose to draw a circle, but the circle is not perfect. And the circle would have been even less perfect in the past, before I had some experience of drawing. So my ability in this case can be improved by practice.

In a similar way, by the use of biofeedback, people can sometimes learn to change their body in various ways that one cannot normally control. Naturally, there are limits to this technique; no one will use it to obtain power over the movement of the stars.


Desire and The Good

A confusing thing about the meanings of one and many  is that the meaning of each seems to depend on the other. The reality behind this is that there is a back and forth process in which each is used to understand the other better. First we understand being, which is something one, although without the specific idea of unity. Then we understand distinction, which implies several things, again without the specific idea of “many.” Then we understand the one by contrast with things that are distinct. Finally we understand the many as a whole composed of ones as parts.

A similar thing happens with the meanings of “desire” and “good”. Thus St. Thomas defines the good in reference to desire:

I answer that, Goodness and being are really the same, and differ only in idea; which is clear from the following argument. The essence of goodness consists in this, that it is in some way desirable. Hence the Philosopher says (Ethic. i): “Goodness is what all desire.” Now it is clear that a thing is desirable only in so far as it is perfect; for all desire their own perfection. But everything is perfect so far as it is actual. Therefore it is clear that a thing is perfect so far as it exists; for it is existence that makes all things actual, as is clear from the foregoing (3, 4; 4, 1). Hence it is clear that goodness and being are the same really. But goodness presents the aspect of desirableness, which being does not present.

But he also seems to define desire in relation to the good:

I answer that, We must needs assert that in God there is love: because love is the first movement of the will and of every appetitive faculty. For since the acts of the will and of every appetitive faculty tend towards good and evil, as to their proper objects: and since good is essentially and especially the object of the will and the appetite, whereas evil is only the object secondarily and indirectly, as opposed to good; it follows that the acts of the will and appetite that regard good must naturally be prior to those that regard evil; thus, for instance, joy is prior to sorrow, love to hate: because what exists of itself is always prior to that which exists through another. Again, the more universal is naturally prior to what is less so. Hence the intellect is first directed to universal truth; and in the second place to particular and special truths. Now there are certain acts of the will and appetite that regard good under some special condition, as joy and delight regard good present and possessed; whereas desire and hope regard good not as yet possessed. Love, however, regards good universally, whether possessed or not. Hence love is naturally the first act of the will and appetite; for which reason all the other appetite movements presuppose love, as their root and origin. For nobody desires anything nor rejoices in anything, except as a good that is loved: nor is anything an object of hate except as opposed to the object of love. Similarly, it is clear that sorrow, and other things like to it, must be referred to love as to their first principle. Hence, in whomsoever there is will and appetite, there must also be love: since if the first is wanting, all that follows is also wanting. Now it has been shown that will is in God (19, 1), and hence we must attribute love to Him.

This seems circular. Desire is a tendency towards the good, while the good is something that is desirable.

The correct response is that here too we have a back and forth process where each thing makes the other understood better. The first thing in this order is desire, but for the moment without the specific idea of tendency towards the good. Taken in this way, it expresses a way of feeling, a sensible experience. It does not matter here whether we take desire in particular, or its principle, namely love, or its consequence, namely pleasure or joy, or their opposites, such as hate, aversion or sadness. In any case we wish to consider them in a very subjective way, as a way of feeling.

Taken in this way, we can consider them much like a kind of sensation. People sometimes ask how we know that pain is a property of the one who feels pain, rather than of the object that inflicts pain. It seems perfectly possible to say that “this knife is painful” could be just as much an objective fact about the knife, as the fact that the handle of the knife is brown. Of course, no one actually believes this. But the question is why they do not.

It would be easy to suppose that the experiences themselves, namely of seeing the knife and being cut by it, are self explanatory. Of course being cut by a knife is something that happens to me, and of course the color of the knife is a property of the knife.

I agree with the conclusion, naturally, but I do not agree with the reasoning. I do not think that we know this in virtue of the experiences themselves. I think we learn it, very quickly and without a need for conscious attention, from the contexts in which those experiences happen. As I said in the linked post on truth in the senses, sensations are not descriptions of a thing, and they do not make claims. Pain does not assert, “I do not belong to this painful thing”; it does not say anything. Nor does color assert, “I am a property of this body.” It does not say anything. And if we simply consider the sensations as such, we could not give a reason why pain could not be a property of the painful thing, nor why color could not be a property of ourselves rather than the thing. But the contexts in which we have these sensations teach us that color belongs to the colored object, and pain to ourselves, rather than to the painful thing.

Consider the case of sadness. It is easy enough to see that sadness is a property of ourselves, and not of an objectively sad fact. Part of the reason it is easy to see this is that we can be sad, and we can know that we are sad, without noticing any particular reason for being sad. In other words, it is the context of the experience that shows us that it is a property of ourselves.

Something similar is the case with love and desire. Insofar as they are feelings that can be experienced, they can be experienced without noticing any particular object. Katja Grace talks about this situation:

Sometimes I find myself longing for something, with little idea what it is.

This suggests that perceiving desire and perceiving which thing it is that is desired by the desire are separable mental actions.

In this state, I make guesses as to what I want. Am I thirsty? (I consider drinking some water and see if that feels appealing.) Do I want to have sex? (A brief fantasy informs me that sex would be good, but is not what I crave.) Do I want social comfort? (I open Facebook, maybe that has social comfort I could test with…)

If I do infer the desire in this way, I am still not directly reading it from my own mind. I am making educated guesses and testing them using my mind’s behavior.

In this way, it is possible to feel desire as a mere feeling, without defining it in reference to something good. And this kind of feeling is the origin of the idea of “desire,” but it is not yet sufficient.

We learn from experience that when we have desires, we tend to do things. And we notice that not all desires are the same, and that when we have similar desires, we end up doing similar things. And so from this we get the idea of the good as the end and final cause of our actions. We do similar things when we have similar desires, and what those things have in common is that they result in the same ends, even if they use different means. So the end is “why” and explains the choice of means.

In turn, this understanding of the end allows us to understand desire more precisely, now as an inclination towards the good.