If I didn't know, from my own case, that I'm conscious, my knowledge of your neural processes would give me no reason to suspect that you are.
Perhaps everything has external and internal aspects. The external properties are those that science can capture and describe--through interactions, in terms of relationships. The internal aspect is the intrinsic essence; it is the reality that is not expressible in the language of interactions and relations.
Some advocates of science insist that questions science cannot answer are meaningless, but I find this unconvincing--and unattractively narrow-minded. The pursuit of science has led me to conclude that the future is open and novelty is real.
The observational record tells us unambiguously that the universe is getting more interesting as time goes on.
To be human is to live suspended between danger and opportunity.