Premise: our representational system has had a relatively invariant core throughout human history (cf. Sellars's manifest image). Major theses: (i) When philosophical argument establishes the existence of an entity, that entity is a representing, not a represented. (ii) Most of the documents in the history of philosophy are on a par (as dialogical resources) with current philosophical literature for establishing or controverting such existence claims. (iii) The use of mathematics (initially the mathematized neo-Platonism of classical mechanics) allowed modern physical science (...) to break with the perennial system of representation; in consequence, a portion of the representings of modern physical scientists do not belong to the historically invariant core. This limits the dialogical resources of physical science and the applicability of arguments from perennial philosophy to science. It also explains the relative irrelevance of pre-17th century science to contemporary physical scientists in contrast to the relevance of pre-17th century philosophy to contemporary philosophers. It also supports thesis (iv), that logic (broadly conceived) in central to all serious philosophical enterprises, since logic is the central tool for exhibiting and criticizing the rationale(s) of our representational system(s). Support for these theses will be found in the paper. (shrink)