  Notice that the default interpretation of a term is its proper sense, defined as “the signification properly and principally given to it”. The proper signification of a term must be based on the fact that “utterances were primarily and principally imposed to signify so as to stand for their ultimate significata, and not for themselves” (S 4.3.2:  256);[18]  that is to say, just as concepts (at least in the first instance) naturally signify those extra-mental things that just as naturally give rise to them, so spoken and written terms (at least in the first instance) are imposed to signify, via their corresponding concepts, the same ultimate  significata.[19]  For Buridan, this capacity is natural to us as creatures endowed with the power of cognition. It is why he insists that determining the nature of concepts pertains not to logic but to psychology or metaphysics, speculative sciences whose conclusions cannot be otherwise (QDI I.3:6, ll.  4–10).[20]  So even if we say that the proposition, ‘Man is a species’ is true insofar as it is put forward in the context of Aristotle's Categories, it is not literally true, or true according to “the signification properly and principally given to it”, because of no per se existing man is it true to say that he is a species. What happens is that when we work on the Categories, we follow Aristotle's lead and depart from conventional usage in such a way that the term ‘man’ supposits not for individual men but for the universal concept according to which it was imposed to signify, in which case the proposition is true because “species and genera are universals according to predication” (S 4.3.2: 254). So it can be true that man is a species without it being literally true that man is a species.