'Conscious experience is a widespread phenomenon. It oc-
curs at many levels of animal life, though we cannot be sure of
its presence in the simpler organisms, and it is very difficult to
say in general what provides evidence of it. (Some extremists
have been prepared to deny it even of mammals other than
man.) No doubt it occurs in countless forms totally unimagi-
nable to us, on other planets in other solar systems throughout
the universe. But no matter how the form may vary, the fact
that an organism has conscious experience at all means, basi-
cally, that there is something it is like to be that organism.
There may be further implications about the form of the expe-
rience; there may even (though I doubt it) be implications
about the behavior of the organism. But fundamentally an or-
ganism has conscious mental states if and only if there is some-
thing that it is like to be that organism – something it is like for
the organism.'

What Is It Like to Be a Bat?

Thomas Nagel, 1974