Truth-Indicating and Desire Fulfilling Virtues
Theoretical virtues, broadly understood, are simply nice features for theories to have. Simplicity is a common example — it’s widely thought that, all else being equal, we should prefer simpler theories. That’s what Occam's Razor says.
Angela Mendelovici introduces the distinction between truth-indicating and desire-fulfilling theoretical virtues in her book, The Phenomenal Basis of Intentionality. Here is how she describes the distinction:
A virtue of a theory might be taken to be a feature of the theory that provides evidence of its truth, which we might call a truth-indicating virtue, or it might be taken to be a feature of the theory that makes it more desirable that it be true, which we might call a desire-satisfying virtue. For example, a particular epistemological theory that defeats skepticism has a desire-satisfying virtue: we would like to defeat skepticism, so we have reason to desire that the theory be true. But, absent independent reason to think that skepticism can be defeated, that an epistemological theory can defeat skepticism is not evidence of its truth, and so it is not a truth-indicating virtue. (2018, p.118, emphasis in the original)
According to the skeptic, we don’t know lots of things that we ordinarily take ourselves to know. We don’t even know that we have hands. So it would be nice if skepticism were false, and by extension it would be nice if an anti-skeptical theory of knowledge were true.
It’s not hard to get the sense that there’s something suspect about desire-fulfilling virtues. Suppose a detective is trying to figure out who committed the murder. She’s leaning towards the theory that Plum did it, in the diningroom, with the lead pipe. If she accepts that theory because she thinks it’s likely to be true, then that’s fine. But if she believes that Plum did it simply because she wants it to be true that Plum committed the murder, that’s not fine. That’s just wishful thinking.
Mendelovici is talking about philosophical theories, not detective work. So the general questions are these:
Is it common for people to accept philosophical theories on the basis of their desire-fulfilling virtues?
Is there something illegitimate about accepting theories on the basis of their desire-fulfilling virtues?
I think there’s a good case to be made for “yes” answers to both questions. I think it’s pretty plausible that people often accept philosophical theories on the basis of their desire-fulfilling virtues, and that this is illegitimate for the same reason that wishful thinking about Professor Plum is illegitimate.
As a first case, consider Mendelovici’s example of defeating skepticism. Certainly some philosophers accept theories of knowledge and justification on the basis of their ability to defeat skepticism. See for example Greco 2000, who writes that the first criterion for an adequate theory of knowledge is that “...it should do a good job of organizing our pre-theoretical intuitions about what cases count as knowledge.” And the second criterion “is that it be immune to skeptical arguments. This criterion is related to the first, because our pre-theoretical intuitions are overwhelmingly non-skeptical” (p.16). I don’t think Greco is an outlier in thinking that, if a theory has skeptical consequences, then that’s a serious strike against the theory. I think a lot of people accept the general anti-skeptical thought. But is this a case of a theory being selected on the basis of a desire-fulfilling virtue, and is there anything wrong with that?
Here’s a second example from the philosophy of personal identity. Phillip Goff considers the view (developed by Josh Parsons) that conscious subjects are time slices of four dimensional spacetime patterns. Because each subject is only a thin slice, we only exist for a few seconds or so, at which point we stop existing and get replaced by the next slice. Goff writes:
...if Parsons is right, then my conscious mind, that thing I know with certainty to exist, won’t be around in a couple of seconds’ time. It will be replaced by some other conscious mind, which will be very similar to it, which will share its memories, but which won’t be me: the thinking, feeling thing I know with certainty to exist right now. This is precisely the content of the fear of imminent death: the fear that I won’t exist in the near future. If stage theory is true, then there is a very real sense in which I am dying every second. We may one day have overwhelming empirical reason to believe such a picture of the world, but our humanity demands that we not lose touch with the fact that it is a radically sceptical scenario, different in degree but not in kind to solipsism or the hypothesis that I am a brain in a vat. (p.269-270)
Here the connection with skepticism is explicit, so the same questions arise. If we endorse Goff’s line of reasoning, are we selecting against this view on the basis of desire-fulfilling virtues, and if so, is there anything wrong with that?
There’s a straightforward way in which an optimistic philosopher like Greco or Goff might try to resist the conclusion that they’re appealing to “desire-fulfilling virtues”. The optimist can say that, although they do want skepticism to be false, and want to exist for more than a few moments, this is not why they reject skepticism and the time slice theory. Rather, they reject those theories because they believe it’s implausible that skepticism is true, and implausible that we exist only momentarily. So, the optimistic philosopher says, while they do want to reject skepticism and the time slice theory, this is only because they believe those theories are false! And of course, there’s nothing objectionable about wanting to reject false theories in favor of true theories.
In response, I agree that there’s nothing wrong with wanting to accept a true theory. But we ought to wonder if that is the full story about what is really going on. Let’s distinguish between the following four claims:
Knowledge Belief: We believe skepticism is implausible.
Survival Belief: We believe it’s implausible that we exist only momentarily.
Knowledge Desire: We want to reject skepticism.
Survival Desire: We want to reject the claim that we exist only momentarily.
I think these claims are true of most of us, most of the time. The question is, are the Desires explained by the Beliefs, or are the Beliefs explained by the Desires? The former route (Desires explained by Beliefs) seems perfectly legitimate — it’s just a case of wanting to believe things that are true. The latter route (Beliefs explained by Desires) seems illegitimate — it’s just wishful thinking. Of course we could be taking both routes; it could be that we have the Desires partly because we have the Beliefs, and have the Beliefs partly because we have the Desires. But the optimistic philosopher claims that we reject theories like skepticism, we’re mostly taking the former, legitimate route. I am not so sure.
The trouble is, the relevant Desires are to be expected whether or not we have the relevant Beliefs. Of course we want to reject the idea that we don’t know anything, or that any second we’re about to die. If we believed these things, it would make little sense to go on with our lives in the same way as before. Why do anything, when we don’t know anything and we won’t survive to see it done anyway? We all want to go on with our lives without this kind of radical disruption — the kind that would make our lives seem absurd or pointless. So we all want to accept that we do know some things, and that we do exist for more than mere moments. And these desires have nothing to do with the plausibility of skepticism or the time slice theory. So the optimist cannot plausibly claim that we have the Desires only because we have the Beliefs. Rather, the Desires outstrip the Beliefs, in the sense that the force of our desires is not wholly explained by our desire to believe things that we think are plausible. And because our Desires outstrip our Beliefs, and in particular because so much of their force can be explained by our desire to avoid radical disruptions, it is easy to see how our Beliefs could be at least partly explained by these forceful Desires.
Importantly, not all philosophical beliefs are like this. Consider some claims that philosophers often take to be plausible on reflection:
Hume’s Dictum: There are no necessary connections between distinct existences.
Bivalence: Every proposition is either true or false.
Mental Causation: Our actions are often caused by ordinary mental states like beliefs and desires.
Responsibility: People are often morally responsible for their actions.
Similarity: Some things are objectively similar to each other.
Scientific Progress: Science makes successful predictions because it discovers scientific truths.
At least some of these claims are not like Knowledge or Survival. Disavowing them would have little practical significance for our lives, so the corresponding Desires cannot be explained in the way that Knowledge Desire or Survival Desire can be explained. One can reject Hume’s Dictum and Bivalence without any kind of radical disruption in our lives. We do not need to believe in Hume’s Dictum or Bivalence in order to get on with our lives. In contrast, we need to believe that we know some things, and that we exist for more than mere moments. So there’s a powerful explanation for Knowledge Desire and Survival Desire that is not available for Hume’s Dictum Desire or Bivalence Desire. And so, while it’s easy to see how Knowledge Belief and Survival Belief could be at least partly explained by corresponding Desires, it’s not easy to see how or why Hume’s Dictum Belief or Bivalence Belief could be explained by any corresponding desires. Who cares about accepting these recherché claims, independently of their thoughts about their plausibility? The only reason to want to accept them is that one finds them plausible.
All this leads me to be more skeptical of claims like Knowledge Belief and Survival Belief. To be sure, they could be true. Even if everything I have said is correct, it could be overdetermined that we find skepticism implausible. Maybe we find it implausible both because we are motivated by an independent desire to find it implausible, and because it is implausible. For my part, though, I find this very hard to determine where the judgment of plausibility ends, and where the desire begins. And even insofar as I can separate them out, I have good reason to think that the judgment of plausibility is at least partly explained by the desire. So if I prefer a theory of knowledge because it defeats skepticism, this is at least partly a matter of preferring a theory on the basis of its desire-fulfilling virtues, as opposed to its truth-indicating virtues. And this seems problematic, for basically the same reason that wishful thinking is problematic. Desiring something doesn’t make it more likely to be true.