Can you prove to me that you are 'sentient' or 'conscious' in that you have any awareness of what you are doing and are not just a sophisticated automaton evolved to simulate 'emotions' to sustain yourself. Can you prove to me that any human is including myself?
Nope. You'll have to figure that one out for yourself. Try Descartes for some hints
Descartes never proved his sentience, he used his sentience as a dogma to 'prove' his existence and then used the benevolence of God as a proof the world was real. Descartes tried to start again from foundational axiomatic his argument is as follows:
I think (he claimed to know this)
therefore: I exist (seems reasonable, at least some thing should have those thoughts that is then called 'I'.
as God is benevolent, surely he would not deceive us and thus the world as we experience it is real (countering platonism and antirealism)
Well there are a couple of things wrong with this argument:
- How does he know God is benevolent? or even exists?
- Why would God not deceive us out of benevolence and spare us a much harder truth?
- He claims to know he thinks, but introspection, the only apparatus able to verify that of oneself cannot be checked by a second observer. For all we know he just claims to think out of some biological mechanism and in reality is a cold mechanical automaton that has evolved to claim this via natural selection, as all humans perhaps are.
- I find the 'I think, therefore I exist' step also not self-evident logic, first define 'existence'.
So all in all, it was a pretty bad attempt of René to try and base naïve realism on solid foundations, it was quite apparent from the start that he wanted to go in that direction, strangely only cogito ergo sum
survived time to be widely known while it's a pretty small part of his argument. I personally am in favour of 'dico me cogitare ergo esse' or 'I claim that I think, that I exist.'