Peirce made contradictory statements about the place of materiality in the categories. At one point he declared matter to be a Second (Essential Peirce, vol. 1, 297). Elsewhere he described “the permanence of mass, momentum, and energy” as a type of Thirdness (Essential Peirce, vol. 1, 279), a position that reappears later (Essential Peirce, vol. 2, 186–87). There’s a logic to both stances. But on another occasion, Peirce wrote more extensively:
We not only have an immediate acquaintance with Firstness in the qualities of feelings and sensations, but we attribute it to outward things. We think that a piece of iron has a quality in it that a piece of brass has not, which consists in the steadily continuing possibility of its being attracted by a magnet. In fact, it seems undeniable that there really are such possibilities, and that, though they are not existences [i.e., Seconds], they are not nothing. They are possibilities, and nothing more. But whether this be admitted or not, it is undeniable that such elements are in the objects as we commonly conceive them. (Essential Peirce, vol. 2, 269; Peirce’s italics)
His emphasis on possibility suggests a position similar to critical realism, which identifies three ontological domains: the real, the actual, and the semiosic. The domain of the real consists of causal powers and generative mechanisms as they exist transfactually, whether or not their powers are being exercised; they exist as possibilities, capacities and tendencies. Powers and generative mechanisms are ontologically anterior to their actual interactions—their cause-and-effect relations—which produce the events that constitute the domain of the actual. Finally, we perceive and interpret some portion of the actual: such interpretations compose the semiosic domain.1 Strictly speaking, the domain of the real includes not just material entities, but also ideas, since they too have causal powers, a point that accords with Peirce’s analysis that the sign is “a power . . . to determine some interpretant” (CP 1.542; Peirce’s italics). Thus the domains parallel Peirce’s categories, and might be equivalent to what Peirce called “universes” (Essential Peirce, vol. 2, 478-79; but cf. 435, which seems to drive his universes in an idealist direction). These parallels justify my position that materiality should be considered a First.
But why is the inconsistent among Peirce’s statements? One reason could be that his views evolved. But another is that context matters, so it could be he has different aspects of materiality in mind during the various instances he addressed the matter. From this perspective, consider his case for the concept of “real possibility.” He gives the example of a diamond that had formed but then had been destroyed before ever being pressed by anything hard: was it hard or not? Clearly, a diamond is a diamond whether it’s been tested for hardness or not, because a diamond has a certain set of properties, so if it had instead been tested, it would have been hard (Essential Peirce, vol. 2, 354-57). He concludes,
what does that behavior [of a material substance] consist in, except that if a substance of a certain kind should be exposed to an agency of a certain kind, a certain kind of sensible result would ensue, according to our experiences hitherto. As for the pragmaticist, it is precisely his position that nothing else than this can be so much as meant by saying that an object possesses a character. He is therefore obliged to subscribe to the doctrine of a real Modality, including real Necessity and real Possibility. (Essential Peirce, vol. 2, 357; Peirce’s italics)
The diamond’s hardness is transfactual—testing it for hardness is contingent. In other words, whether or not the diamond is actually tested, as a real entity, if it were tested it would exhibit its powers and tendencies, including the hardness it had when it wasn’t tested (see also CP 1.422). So as something bearing certain possibilities which may or may not be tested, it is a First. Otherwise his use of the word “possibility” would be meaningless or misleading. But should a particular condition or circumstance arise, it would behave in such-and-such a way, as a natural necessity. It follows a law, which is a Third.
I’m uncertain how to parse this, but my but guess at the moment (I’m sure Peirce scholars have explored it thoroughly) stems from Peirce’s distinction between two “generals” (generalities): qualities and laws. I’m inclined to view the qualities qua Firsts as static, whereas law-like behavior is the tendency (Thirdness) that regulate its actions or behaviors (Secondness). There are also probabilities that are rooted not in material qualities but in other ones: if you repeatedly flip a coin, the probability is that you’ll increasingly approach an equal number of heads and tails, which I suppose is the result of the coin’s formal properties (having two flat sides makes it far more likely the coin will land on a side rather than the slim edge). But material’s aspects as both First and Third would seem to leave Secondness out of the picture, except insofar as it’s a degenerate Third, perhaps insofar as one doesn’t examine its behavioral tendencies.