 a priori justification and knowledge |  certainty |  Descartes, René |  Descartes, René: modal metaphysics |  Descartes, René: theory of ideas |  Gassendi, Pierre |  idealism |  -->idealism: British--> |  -->ideas--> |  innateness: historical controversies |  justification, epistemic: foundationalist theories of |  knowledge: analysis of |  moral particularism |  original position |  perception: epistemological problems of |  primary and secondary qualities in early modern philosophy |  rationalism vs. empiricism |  realism |  reasoning: defeasible |  sense data |  skepticism |  truth 