We are in the habit of attributing experience to other humans, to a lesser degree to other primates, and so on to other life forms in proportion to their similarity to us, and perhaps their complexity. We don’t usually attribute experience to simple nonliving entities; we don’t feel that a stone feels anything. Why not?
Everything has some quality, which in Peircean terms is its Firstness. But according to Peirce, Firstness can only be apprehended as a mode of feeling, and ‘whatever is First is ipso facto sentient’ (CP 6.201, RLT 260).
Firstness may be defined as follows: It is the mode in which anything would be for itself, irrespective of anything else, so that it would not make any difference though nothing else existed, or ever had existed, or could exist. Now this mode of being can only be apprehended as a mode of feeling. For there is no other mode of being which we can conceive as having no relation to the possibility of anything else. In the second place, the First must be without parts. For a part of an object is something other than the object itself. Remembering these points, you will perceive that any color, say magenta, has and is a positive mode of feeling, irrespective of every other. Because, Firstness is all that it is, irrespective of anything else, when viewed from without (and therefore no longer in the original fullness of firstness) the firstnesses are all the different possible sense-qualities, embracing endless varieties of which all we can feel are but minute fragments. Each of these is just as simple as any other. It is impossible for a sense quality to be otherwise than absolutely simple. It is only complex to the eye of comparison, not in itself.
— Peirce, RLT 147, PM 167 (1898)
When we say that a stone has its quality, its Firstness, we are taking its itness – separate existence, identity – for granted. We are viewing it from without, which precludes seeing ‘the original fullness of firstness.’ Like the stone itself, any qualities we attribute to it have become other to something else, and thus lost the indeterminacy and spontaneity which is theirs as possibilities rather than actualities. This is why we do not think of the stone (or its quality) as sentient, or as experiencing. And yet, the life and fullness of Firstness has not departed, according to Peirce, but is still here in ‘the mode of being of that which is whatever it is regardless of anything else’ (CD ‘Firstness’). Can you sense it?