“The principles of philosophy are certain truths within the immediate ken of every human person,” writes Ralph McInerny ( Praeambula Fidei: Thomism And the God of the Philosophers ).  His first example: “Who could fail to grasp being, since it is grasped in anything we conceive?”

Who indeed?  Well, practically everyone.  When a normal person “grasps” something conceptually, he typically thinks he’s grasping the thing .  If I think about teapots, my thoughts are occupied with the specifics of teapots.  I don’t have a thought about “being” at all, and for many people it would take a good bit of instruction to train them to think they are thinking about being when they thought they were thinking about teapots.

Philosophy, at least of the kind that McInerny is offering, is by no means instinctive.  One has to be taught to think like a philosopher.

One side note: McInerny also thinks that there’s a moral truth immediately available like the metaphysical truth of being, which is the first principle of practical reason, that good is to be done and evil avoided.  He sums this up as the “moral metatruth” that “you should not to do others what you would not have them do to you.”  Moral metatruth that might be, but it’s not what Jesus teaches.