Alternative Self-Defeat Arguments
Here, I defend the Self-Defeat Argument for Phenomenal Conservatism against an objection.*
[ *Based on: “Alternative Self-Defeat Arguments: A Reply to Mizrahi,” Logos and Episteme 5 (2014): 223-9. ]
1. The Self-Defeat Argument for PC
Phenomenal Conservatism (PC) holds that you are (to some degree) justified in believing whatever seems to you to be the case, as long as you have no grounds for doubt. The Self-defeat argument for PC says something like this:
All our beliefs (that are reasonable candidates for being justified) are based upon appearances.
A belief is (doxastically) justified only if what it is based upon constitutes an adequate source of (propositional) justification.
So, if appearances are not a source of (propositional) justification, then all our beliefs are (doxastically) unjustified (including the belief that appearances are
not a source of justification).
So it’s self-defeating to deny that appearances are a source of justification.
(Note: “propositional justification” is justification that one has for believing a given proposition, regardless of whether one actually believes it. “Doxastic justification” refers to having a belief that is actually justified. So (2) says that a belief is actually justified only if it’s based on something that provides justification for the believed proposition.)
2. Parody Argument: Evidentialism
Moti Mizrahi raises the objection that parallel self-defeat arguments could be given for many other theories of justification. E.g., here’s a self-defeat argument for evidentialism:
1*. All our beliefs are based upon evidence.
2. A belief is justified only if what it is based upon constitutes an adequate source of justification.
3*. So, if evidence is not a source of justification, then all our beliefs are unjustified.
(Aside: Evidentialism, actually, isn’t the view that evidence is a source of justification; it is the view that only evidence can be a source of justification. But nevermind that.)
But as this example shows, the Phenomenal Conservative need not be troubled by all such parody arguments. I’m perfectly happy with (3*), and I’m happy to say that evidence is a source of justification. So why is this an objection?
It might be an objection if evidentialism were incompatible with PC, or if evidentialism were just implausible. But neither of these is the case. Evidentialism (here understood as the view that evidence is a source of justification) is very plausible, and it is compatible with PC. Indeed, PC might just be a form of evidentialism – the form that says seemings constitute evidence.
3. Parody Argument: Tea Leaves
Maybe evidentialism was just an unfortunate choice of example. Maybe the point is that self-defeat arguments of comparable plausibility to mine could be constructed for many implausible theories of justification, and therefore my argument must be misguided.
But this isn’t true. Take an example: The self-defeat argument for the Tea Leaf Theory of Justification:
1'. All our beliefs are based upon tea leaf readings.
2. A belief is justified only if what it is based upon constitutes an adequate source of justification.
3'. So, if tea leaf readings are not a source of justification, then all our beliefs are unjustified.
So it’s self-defeating to reject tea leaf readings.
But that argument is totally implausible because its first premise (1’) is obviously false – unlike my argument. My premise 1--
All our beliefs (that are reasonable candidates for being justified) are based upon appearances.
--is much more plausible.
4. Mizrahi’s Defense
I am unsure why Mizrahi thought that one could construct self-defeat arguments for many other theories. He writes:
I submit that any basic source of propositional justification [...] can be plugged into the following argument scheme instead of X:
All our beliefs (in relevant cases) are based upon X.
A belief is (doxastically) justified only if what it is based upon constitutes an adequate source of (propositional) justification.
∴ If X is not a source of justification, then all our beliefs are unjustified [...].
This is so because any theory of basic propositional justification that identifies X as a basic source of justification would have to appeal to X in order to justify itself on pain of self-defeat. Since the ‘in the relevant cases’ is supposed to rule out beliefs that are clearly not justified, the remaining beliefs must be justified in virtue of being based upon X.
My best guess is that Mizrahi was thinking that my basis for asserting my premise 1 is that according to my theory, all our beliefs that are reasonable candidates for being justified must be based on appearances, because I think that appearances are the only source of justification. I.e., he was thinking that I had a blatantly question-begging rationale for (1). If so, then I guess the blatantly question-begging rationale for 1' (all our justified beliefs must be based on tea leaf readings, because tea leaf readings are the only source of justification) would be comparable. Both arguments would then be equally bad.
But that wasn’t my reason for asserting (1). My reason for asserting (1) was introspection: When you think about it, it’s hard to think of any belief (that seems like a reasonable candidate for a justified belief) that isn’t based on appearances. E.g., my belief that there’s a table in front of me now is based on my visual experience of a table (which is a type of appearance). My belief that the shortest path between any two points is a straight line is based on my intuition that that is the case (i.e., it just seems obvious). That’s another kind of appearance. My belief that I woke up at 8 this morning is based on my apparent memory of this, which is a third type of appearance. To agree with these comments, you don’t have to already accept PC; these are just plausible to normal people on reflection.
Maybe Mizrahi had something like this in mind: Suppose you think that X is the ultimate source of all justification. In that case, you’d have to think that all justified beliefs are based on X. You would then be committed to endorsing something similar to my premise 1, but saying that all beliefs that are reasonable candidates for justification are based on X. Then (assuming you accept 2, which nearly everyone does), you’d be committed to thinking that there is a sound self-defeat argument for your view.
However, this shouldn’t really trouble me. It shouldn’t trouble me if people with false theories would be committed to claiming that there is a sound argument for their view (that’s always the case!). It would only trouble me if I was committed to thinking there was a sound argument for their view. But I’m not. Alternately, it would trouble me if there was an equally plausible self-defeat argument for a rival view. But there isn’t (as far as I know).
5. Parody Argument: Acquaintance
One leading alternative to PC is the acquaintance theory, the theory that the foundational justified beliefs are based upon states of acquaintance, a kind of direct awareness with certain objects. Note: acquaintance differs from appearance at least in this respect: It’s possible to have an appearance of something that does not in fact exist, but it is (by definition) impossible to be acquainted with something that does not exist.
So here’s another self-defeat argument:
1#. All our beliefs are based upon acquaintance.
2. A belief is justified only if what it is based upon constitutes an adequate source of justification.
3#. So, if acquaintance is not a source of justification, then all our beliefs are unjustified.
In this case, premise (1#) might seem about equally plausible as my (1).
However, I would just argue that (1#) is mistaken. All the cases you might think were explained by (1#) are really explained by (1). Consider …
Case 1: Tizy sees a squirrel. Everything is normal. She (justifiedly) comes to believe that there’s a squirrel before her.
Is the justified belief explained by her acquaintance with the squirrel? Or is it instead explained by the appearance of a squirrel? I claim it is the latter, which you can see by considering …
Case 2: There is no squirrel present, but Tizy has a perfectly realistic hallucination of a squirrel. She has no reason for suspecting that she is hallucinating.
In this case, what would Tizy believe? Surely, she would believe there was a squirrel before her, exactly as in Case 1. But in Case 2, Tizy is not acquainted with a squirrel, since (as we said above) it is impossible to be acquainted with something that does not exist. This shows that what explains our beliefs, in general, is not our acquaintance with things but our having appearances of things.
Objection: Most acquaintance theorists would deny that you can be acquainted with physical objects (such as squirrels) anyway. They would say beliefs about squirrels are inferential, so that was a bad example.
Okay. But most acquaintance theorists would say that you can be acquainted with some abstract objects, whereby you can have foundationally justified beliefs in certain simple, necessary truths. E.g., you might know the axioms of a mathematical system by acquaintance with the natures of mathematical objects. So here’s a new example:
Case 3: Frege thinks about the Comprehension Axiom of naïve set theory. It seems obviously true to him. He also thinks about the Axiom of Extension, which also seems obviously true. He believes both.
The Axiom of Extension is true, so Frege might be acquainted with that fact. But the Comprehension Axiom is false (due to Russell’s paradox), so Frege could not be acquainted with the fact that makes it true.
Yet Frege believes both axioms. It seems that he believes them for the same sort of reason. (He cannot tell any difference between how he comes to form these two beliefs.) That reason cannot be acquaintance, as we’ve said. So it must be that both are based on appearance (the axioms just seem true to him).
So premise (1#) is false: The beliefs that you might think to be based on acquaintance are really based on appearance.
6. Conclusion
The self-defeat argument only works for PC. That’s because it’s plausible and true that our beliefs are based on appearances; it’s just false that they’re based on acquaintance, tea leaf readings, or anything else.