Friday, October 16, 2015
"Can I Prove I'm not Delusional?"
What it is to prove something? In one sense it is to give a proof--to give an argument. Here is an argument that I am not delusional:
I am not delusional.
Thus, I am not delusional.
The argument is valid (p, thus p). And if the first premise is true then the argument is also sound. But of course it begs the question. What one would like is a sound (or cogent) argument the premises of which are (at least initially) more obvious than the conclusion.
Can any such proof be given? I wouldn't know what the proof would be.
Someone who is (seriously) delusional has cognitive faculties which are unreliable in forming true beliefs. A seriously delusional person might believe that he is an egg, that the earth is the sky, that 2+2=5, that his cognitive faculties are functioning properly when indeed they are not, etc.
Suppose one tried the following inductive argument:
1. Yesterday I saw a building.
2. The day before I saw the same building.
3. The day before that I saw the same building.
8. My friend Jack tells me he saw the same building.
9. My friend Jill reports that there is a building in that very location.
15. So my faculty of sight is properly functioning.
But a problem arises. In 1-3 I am assuming that my faculty of sight is working properly. In 8-9 I am assuming that my faculty of testimony is functioning properly. (Moreover, in presenting an argument I assume that my faculty of inference is reliable.) Of course I could use my faculties of touch and smell to validate that my faculty of sight is reliable. But then I enter into an epistemic circle assuming one sense faculty is reliable in proving that the others are reliable. In short, in giving any proof that I am not delusional I must tacitly assume that at least some segment of my cognitive faculties are functioning properly.
The question is whether this sort of circularity is malignant or benign.