Not too many years ago I stayed up late drinking and arguing with an old friend about our different world views. I’m a sceptical atheist and a physicalist, and she…well she believes in a lot of things that I don’t. At one point I said something like, “If at some point in the future I started believing in those things, then from my present perspective I’d have to say that I’d gone crazy.” I didn’t mean that I think people who believe things that I don’t are insane, only that if I believed them then something seriously wrong must be happening with my thought processes.
Less than a year later I started to believe in astrology. As it turns out I had gone crazy and my belief in astrology was delusional: it was a result of my illness and went away when I was treated. At the time I didn’t think my new belief was odd, despite what I’d said to my friend, because I thought that I now had an insight into how astrology worked (it seemed obvious given the fractal nature of the Universe).
It’s slightly disconcerting knowing that my core beliefs can be affected by my illness: I’d feel much more comfortable thinking that they’re fixed and unchangeable. After all, aren’t they what make me who I am?
Ah, but if you’re a physicalist, then your core beliefs must be tied up in your brain/body somehow, because that’s all there is to you, right? And since the body is a chemical system, it stands to reason that changing your brain chemistry could ultimately lead to changing your world view and core beliefs. And maybe who you are is more than the sum of your core beliefs–many people change religions or genders or political parties, but are still “themselves.”
Of course it follows from physicalism that what I believe is a result of the physical state of my brain, and that that can change. That doesn’t trouble me, just that because of my illness my beliefs may be a bit more variable than usual. It’s also amusing that my aberrant beliefs (which a lot of people share) can be treated with medication.
The basic question here I think is how you know whether you’re delusional. From your present perspective, believing in astrology was delusional. Interesting point that you’re uncomfortable that your core beliefs can be changed by your illness. Taking that to a whole new level, when I was psychotic I believed that I was a Mermaid. That was a core belief, borne of a brain chemistry malfunction. Was it true? At the time, yes it was. Now that I no longer believe it, it must have been a delusion. Right?