Hi Sammy (a pseudonym),
I don't want to go too deep into this point, so I'll
keep things brief.
Some years ago, a theistic logician named Alvin Plantinga wrote a book God and Other Minds: A Study of the Rational Justification of Belief in God. In this work, Plantinga argued that belief in God is analogous to belief in other minds. What are minds? How do we know that minds other than ours exist?
By "minds" here, I mean "mental entities." Beliefs and desires are two mental or intentional states, but clearly not the only two states of mind.
Plantinga (similar to Bertrand Russell) seems to contend that one can never demonstrate (apodictically) by rational argumentation that other minds exist. By means of introspection, I can know that I experience certain mental states. But I cannot know that S1 experiences similar mental states because I cannot get into the head (so to speak) of S1. All I can do is
infer that S1 experiences mental states in a manner analogous to my experience of mental states. But the inference is a belief based on probabilistic factors. For all I know, if I could get into the head of S1, I might find that S1, for some reason, does not experience mental states such as beliefs or desires. Maybe S1 is really an android or automaton. But I seem justified in believing S1 does have beliefs or desires, even though I cannot know or prove apodictically that this is the case.
For more insight on this matter, I suggest the
I guess the bottom line is that we believe in many things that can be neither proved nor demonstrated by logic or science. How can science demonstrate or prove that other minds exist? Granted, I believe minds other than my own exist. But I did not arrive at that belief by logical or scientific means. Keep in mind that I am here explaining what the book I Don't Have Enough Faith to Be an Atheist is saying. I believe it makes a good point about things science cannot prove. Astrophysicist Paul Davies also points this out in The Mind of God.