Abstract

The anonymous Summa 'In omni doctrina (In every doctrine)' is a handbook on what is called in medieval philosophy the 'old logic', i.e. the theories of Aristotle, but it shows great interest in the subjects of the typical medieval developments in logic ('the modern logic'), such as in signification, propositions, and terms. It can be dated 1200-1220. Its origin probably is Paris and environment. Its conception of logic emphasizes psychological and epistemological elements such as intellect and thought, in contradiction to earlier manuals. As examples may count that, according to the master, the bearer of truth and falsity is the expression in the mind. The division of propositions according to quantity depends on the combinations made by the soul. Further, some universal terms are universal because of the intellect (for instance 'phoenix'), some because of the intellect and nature ('man'). A syllogism should conclude something other than the premises, something which is not different in reality, because in reality man and animal are the same, but different in the mind.