Ka Ho Lam

In “Two Dogmas”, Quine indicates that Carnap’s Aufbau fails “in principle” to reduce our knowledge of the external world to sense data. This is because in projecting the sensory material to reconstruct the physical world, Carnap gives up the use of operating rules and switches to a procedure informed by general principles. This procedure falls short of providing an eliminative translation for the connective “is at”, which is necessary for the reduction. In dissecting Quine’s objection, I argue that Quine has at best proven the claim that the use of general principles essentially fails the task of radical reductionism. However, in order to establish the conclusion that the Aufbau fails in principle, Quine needs to further vindicate two other claims. They are: first, a switch from operating rules to general principles is necessary; second, the set of general principles Carnap adopts is the best alternative. By disambiguating the notion of “explicit definition” and examining the concept of definability in the Aufbau, I explore the possibility of justifying these two claims that Quine overlooks in his objection. The result suggests that Quine’s objection stands in tension with his radical reductionist reading of the Aufbau.

In this paper, I present a critique of taxonomic pluralism, namely the view that there are multiple correct ways to classify entities into natural kinds within a given scientific domain. I argue that taxonomic pluralism, as an anti-essentialist position, fails to provide a realist alternative to taxonomic monism, i.e., the view that there is only one correct way to classify entities into natural kinds within a given scientific domain. To establish my argument, I first explain why the naturalist approach to natural kinds adopted by pluralists requires them to give up the mind-independence criterion of reality presupposed by monists. Next, I survey two types of pluralist account. I argue that, while the modest pluralist account is not pluralistic enough, the radical pluralist account fails to come up with an alternative criterion of reality that is robust enough to differentiate its position from anti-realism about natural kinds. I conclude by drawing out the implications of my critique for the essentialism/anti-essentialism debate about natural kinds.