Originally Posted by toretorden

You can still gather evidence in favour of something and make one explanation more plausible than others, even if you can't be sure it's 100% correct.

F.ex you can look at a brain scan and record brain activity when people think of different things, so we know that brain activity somehow relates to thinking. We know that when parts of the brain is damaged, that can alter function such as the ability to speak languages or the ability to associate visual sensory input with your knowledge of stuff so that you're able to recognize things you see. Damage to the brain in old people with alzheimers often alters personality.

You can take all that and more and say that's evidence in favour of the following assumption : that if the brain dies and completely decomposes, it's function is lost which is so disruptive to thought processes and personality that this stuff ceases.

That's based on f.ex knowledge of the effects of necrosis in your brain when you're alive. Why should the rules suddenly change? From our general experience, they don't.