Hurford's discussion also vindicates the classical empiricist program in semantics. The idea that PREDICATE(x) is the logical form of the sensory representations encoded via the dorsal and ventral streams validates empiricists' insistence on the psychological primacy of sense data, which have the same form. In addition to knowing the logical form of our primitive representations, however, we need accounts of (1) their contents and (2) how more complex thoughts are derived from them. Ideally, our semantic vocabulary would both reflect the psychological “primitiveness” of these representations and make clear how more complex representations derive from them.