Obviously I'm not looking for a valid deductive proof using formal logic, but at least a relatively convincing argument.
How do I know that humans who I encounter other than myself have sentient minds, and aren't just unfeeling zombies?
It seems unreasonable to use the induction: "I am, in all observable ways, a human, and this human (me) is conscious, so all humans are conscious" or any from of that argument (such as, 'I know of this thing (me) that speaks about consciousness is conscious...) because I only know for certain of one such instance, and I'd never want to make a general induction from just one instance. (Imagine: "this person is a blue-eyed carpenter, so all people must be blue-eyed carpenters")
Is the fact that, from my own perspective, people act and speak as if they have conscious minds, enough for me to conclude that they are indeed conscious? Would it be unreasonable to conclude the opposite, that nobody posses a conscious mind besides for myself?
The only reason why I might be inclined to believe that other people have conscious minds is that I have a hard time believing in zombies, but if philosophical zombies are possible, than it seems more reasonable to conclude that other people are in fact zombies instead of attributing to them the added complexity of a conscious mind. Does anyone discuss the idea that belief in zombies might negate the belief in others' minds?