Discriminatory capacities are involved in several aspects of the cognitive skills of subjects: (i) With some restrictions, perceiving an object X, or perceiving that P, is possible only if the subject can discriminate between X and other objects, or she can discriminate whether P or R (where that R is incompatible with that P). (ii) A principle of transparency postulates that in order to know the meaning X of a linguistic expression a speaker must be able to determinate whether X
is or it is not identical to Z, the meaning of a different expression. (iii) Transparency of content seems also applicable to the concepts possessed by the subject, which compositionally constitute the conceptual contents ascribed in belief sentences. Usually, crucial assumptions on such requirements about discriminability are involved (directly or indirectly) in theoretical discussions on several topics in epistemology and the philosophy of language: use of demonstrative concepts, non-conceptual content, certain skeptical arguments about perceptual knowledge, epistemic status of theories of meaning, belief sentences, generic relations between other representations and what is represented.
Our purpose is to approach each of these topics in a general philosophical framework which also characterized the previous coordinate project, a framework which is mostly naturalist and externalist, but also compatibilist in the sense that it incorporates some acceptable traits of epistemological internalism (reflexive character of the thinker, introspective access to the reasons she has, etc.). The principles about discriminability are congenial to internalist views in philosophy of language and epistemology. A chief hypothesis guiding our research, and which we will try to justify in its different applications to the different problems, is that there are acceptable restricted versions of those principles about discriminability; which entail just the minimal internalist traits compatible with a basically externalist framework.
