I would reply - off the cuff here - that the components of the Canon - Sensations, Pathē, and Prolepseis - have to give us an accurate picture of reality upon which we then build our concepts which can then be either true or false or maybe valid or empty might need better. The pre-rational components on the Canon have to register reality or they're meaningless as a starting point. The idea that the oar is bent is an invalid concept built on the image reflected on our retina. Where the prolepseis fit in is more difficult but I have to think they also register reality before we begin to build concepts on them.
Liked I said, off the cuff.