Decisions as Predictions

Among acts of will, St. Thomas distinguishes intention and choice:

The movement of the will to the end and to the means can be considered in two ways. First, according as the will is moved to each of the aforesaid absolutely and in itself. And thus there are really two movements of the will to them. Secondly, it may be considered accordingly as the will is moved to the means for the sake of the end: and thus the movement of the will to the end and its movement to the means are one and the same thing. For when I say: “I wish to take medicine for the sake of health,” I signify no more than one movement of my will. And this is because the end is the reason for willing the means. Now the object, and that by reason of which it is an object, come under the same act; thus it is the same act of sight that perceives color and light, as stated above. And the same applies to the intellect; for if it consider principle and conclusion absolutely, it considers each by a distinct act; but when it assents to the conclusion on account of the principles, there is but one act of the intellect.

Choice is about the means, such as taking medicine in his example, while intention is about the means, as health in his example. This makes sense in terms of how we commonly use the terms. When we do speak of choosing an end, we are normally considering which of several alternative intermediate ends are better means towards an ultimate end. And thus we are “choosing,” not insofar as the thing is an end, but insofar as it is a means towards a greater end that we intend.

Discussing the human mind, we noted earlier that a thing often seems fairly simple when it is considered in general, but turns out to have a highly complex structure when considered in detail. The same thing will turn out to be the case if we attempt to consider the nature of these acts of will in detail.

Consider the hypothesis that both intention and choice consist basically in beliefs: intention would consist in the belief that one will in fact obtain a certain end, or at least that one will come as close to it as possible. Choice would consist in the belief that one will take, or that one is currently taking, a certain temporally immediate action for the sake of such an end. I will admit immediately that this hypothesis will not turn out to be entirely right, but as we shall see, the consideration will turn out to be useful.

First we will bring forward a number of considerations in favor of the hypothesis, and then, in another post, some criticisms of it.

First, in favor of the hypothesis, we should consider the fact that believing that one will take a certain course of action is virtually inseparable from deciding to take that course of action, and the two are not very clearly distinguishable at all. Suppose someone says, “I intend to take my vacation in Paris, but I believe that I will take it in Vienna instead.” On the face of it, this is nonsense. We might make sense of it by saying that the person really meant to say that he first decided to go to Paris, but then obstacles came up and he realizes that it will not be possible. But in that case, he also changes his decision: he now intends to go to Vienna. It is completely impossible that he currently intends to go to Paris, but fully believes that he will not go, and that he will go to Vienna instead.

Likewise, suppose someone says, “I haven’t yet decided where to take my vacation. But I am quite convinced that I am going to take it in Vienna.” Again, this is almost nonsensical: if he is convinced that he will go to Vienna, we would normally say that he has already made up his mind: it is not true that he has not decided yet. As in the previous case, we might be able to come up with circumstances where someone might say this or something like it. For example, if someone else is attempting to convince him to come to Paris, he might say that he has not yet decided, meaning that he is willing to think about it for a bit, but that he fully expects to end up going to Vienna. But in this case, it is more natural to say that his decision and his certainty that he will go to Vienna are proportional: the only sense in which he hasn’t decided yet, is to the degree that the thinks there is some chance that he will change his mind and go to Paris. Thus if there is no chance at all of that, then he is completely decided, while if he is somewhat unsure, his decision is not yet perfect but partial.

Both of the above cases would fit with the claim that a decision is simply a belief about what one is going to do, although they would not necessarily exclude the possibility that it is a separate thing, even if inseparably connected to the belief.

We can also consider beliefs and decisions as something known from their effects. I noted elsewhere that we recognize the nature of desire from its effect, namely from the fact that when we have a desire, we tend to bring about the thing we desire. Insofar as a decision is a rational desire, the same thing applies to decisions as to other kinds of desires. We would not know decisions as decisions, if we never did the things we have decided to do. Likewise, belief is a fairly abstract object, and it is at least plausible that we would come to know it from its more concrete effects.

Now consider the effects of the decision to go to Vienna, compared to the effects of the belief that you will go to Vienna. Both of them will result in you saying, “I am going to go to Vienna.” And if we look at belief as I suggested in the discussion to this post, namely more or less as treating something as a fact, then belief will have other consequences, such as buying a ticket for Vienna. For if you are treating it as a fact that you are going to go there, either you will buy a ticket, or you will give up the belief. In a similar way, if you have decided to go, either you will buy a ticket, or you will change your decision. So the effects of the belief and the effects of the decision seem to be entirely the same. If we know the thing from its effects, then, it seems we should consider the belief and the decision to be entirely the same.

There is an obvious objection here, but as I said the consideration of objections will come later.

Again, consider a situation where there are two roads, road A and road B, to your destination C. There is a fallen bridge along road B, so road B would not be a good route, while road A is a good route. It is reasonable for a third party who knows that you want to get to C and that you have considered the state of the roads, to conclude that you will take road A. But if this is reasonable for someone else, then it is reasonable for you: you know that you want to get to C, and you know that you have considered the state of the roads. So it is reasonable for you to conclude that you will take road A. Note that this is purely about belief: there was no need for an extra “decision” factor. The conclusion that you will factually take road A is a logical conclusion from the known situation. But now that you are convinced that you will take road A, there is no need for you to consider whether to take road A or road B; there is nothing to decide anymore. Everything is already decided as soon as you come to that conclusion, which is a matter of forming a belief. Once again, it seems as though your belief that you will take road A just is your decision, and there is nothing more to it.

Once again, there is an obvious objection, but it will have to wait until the next post.

Alien Implant: Newcomb’s Smoking Lesion

In an alternate universe, on an alternate earth, all smokers, and only smokers, get brain cancer. Everyone enjoys smoking, but many resist the temptation to smoke, in order to avoid getting cancer. For a long time, however, there was no known cause of the link between smoking and cancer.

Twenty years ago, autopsies revealed tiny black boxes implanted in the brains of dead persons, connected to their brains by means of intricate wiring. The source and function of the boxes and of the wiring, however, remains unknown. There is a dial on the outside of the boxes, pointing to one of two positions.

Scientists now know that these black boxes are universal: every human being has one. And in those humans who smoke and get cancer, in every case, the dial turns out to be pointing to the first position. Likewise, in those humans who do not smoke or get cancer, in every case, the dial turns out to be pointing to the second position.

It turns out that when the dial points to the first position, the black box releases dangerous chemicals into the brain which cause brain cancer.

Scientists first formed the reasonable hypothesis that smoking causes the dial to be set to the first position. Ten years ago, however, this hypothesis was definitively disproved. It is now known with certainty that the box is present, and the dial pointing to its position, well before a person ever makes a decision about smoking. Attempts to read the state of the dial during a person’s lifetime, however, result most unfortunately in an explosion of the equipment involved, and the gruesome death of the person.

Some believe that the black box must be reading information from the brain, and predicting a person’s choice. “This is Newcomb’s Problem,” they say. These persons choose not to smoke, and they do not get cancer. Their dials turn out to be set to the second position.

Others believe that such a prediction ability is unlikely. The black box is writing information into the brain, they believe, and causing a person’s choice. “This is literally the Smoking Lesion,” they say.  Accepting Andy Egan’s conclusion that one should smoke in such cases, these persons choose to smoke, and they die of cancer. Their dials turn out to be set to the first position.

Still others, more perceptive, note that the argument about prediction or causality is utterly irrelevant for all practical purposes. “The ritual of cognition is irrelevant,” they say. “What matters is winning.” Like the first group, these choose not to smoke, and they do not get cancer. Their dials, naturally, turn out to be set to the second position.

 

Smoking Lesion

Andy Egan argues:

The Smoking Lesion

Susan is debating whether or not to smoke. She knows that smoking is strongly correlated with lung cancer, but only because there is a common cause – a condition that tends to cause both smoking and cancer. Once we fix the presence or absence of this condition, there is no additional correlation between smoking and cancer. Susan prefers smoking without cancer to not smoking without cancer, and prefers smoking with cancer to not smoking with cancer. Should Susan smoke? Is seems clear that she should. (Set aside your theoretical commitments and put yourself in Susan’s situation. Would you smoke? Would you take yourself to be irrational for doing so?)

Causal decision theory distinguishes itself from evidential decision theory by delivering the right result for The Smoking Lesion, where its competition – evidential decision theory – does not. The difference between the two theories is in how they compute the relative value of actions. Roughly: evidential decision theory says to do the thing you’d be happiest to learn that you’d done, and causal decision theory tells you to do the thing most likely to bring about good results. Evidential decision theory tells Susan not to smoke, roughly because it treats the fact that her smoking is evidence that she has the lesion, and therefore is evidence that she is likely to get cancer, as a reason not to smoke. Causal decision theory tells her to smoke, roughly because it does not treat this sort of common-cause based evidential connection between an action and a bad outcome as a reason not to perform the action.

Egan’s argument is basically that either she has the lesion or she does not, and she can make no difference to this, and so apparently she can make no difference to whether or not she gets cancer. So if she feels like smoking, she should smoke. If she gets cancer, she was going to get it anyway.

Answering Egan’s question, if there was a strong correlation like this in reality, I would think that smoking was a bad idea, and would choose not to do it.

We can change the problem somewhat, without making any essential differences, such that every reasonable person would agree.

Suppose that every person is infallibly predestined to heaven or to hell. This predestination has a 100% correlation with actually going there, and it has effects in the physical world: in some unknown place, there is a physical book with a list of the names of those who are predestined to heaven, and those who are predestined to hell.

But it has nothing to do with the life you live on earth. Instead, when you die, you find yourself in a room with two doors. One is a green door with a label, “Heaven.” The other is a red door with a label, “Hell.” The doors do not actually lead to those places but to the same place, so they have no special causal effect. You only end up in your final destination later. Predestination to heaven, of course, causes you to choose the green door, while predestination to hell causes you to choose the red door.

You find yourself in this situation. You like red a bit more than green, and so you prefer going through red doors rather than green ones, other things being equal. Do you go through the green door or the red door?

It is clear enough that this situation is equivalent in all essential respects to Egan’s thought experiment. We can rephrase his version:

“Susan is debating whether or not to go through the red door. She knows that going through the red door is perfectly correlated with going to hell, but only because there is a common cause – a condition that tends to cause both going through the red door and going to hell. Once we fix the presence or absence of this condition, there is no additional correlation between going through the red door and going to hell. Susan prefers going through the red door without going to hell to not going through the red door without going to hell, and prefers going through the red door with going to hell to not going through the red door with going to hell. Should Susan go through the red door? Is seems clear that she should. (Set aside your theoretical commitments and put yourself in Susan’s situation. Would you go through the red door? Would you take yourself to be irrational for doing so?)”

It should be clear that Egan is wrong. Don’t go through the red door, and don’t smoke.