I want to clarify my thoughts on basic belief. Specifically, that its intuitive nature is problematic. When I consider the statement that you mentioned(all triangles are three-sided), its truth strikes me immediately, since I grasp the definitions. Admittedly, I am unable to tell you why exactly it may be false. However, nothing justifies my intuition. Propositions may strike me as self-evident even though they are false. Your argument is that a self-evident proposition is true because by understanding it, it is affirmed. That is sheer dogmatism. How do I know that my intuition that a proposition in which the predicate adds nothing to the subject is true? How do I know that the basic rules of logical thought that govern my rational processes do not mislead me? My conclusion is that rational intuition cannot be justified.