The triadic model of signs was built and argued by Peirce as the most primitive basis for applying logic suitable for the real world, with conditionals, continua and context. Truthfulness and verifiability of assertions is by nature variable. Because of the signs’ groundings in logic, Peirce’s three main forms of deductive, inductive and abductive logic also flow from the same approach and mindset. The data models and organizational schema underlying KR should be as close as possible to the logical ways the world is structured and perceived. Peirce’s contributions make a notable difference in how knowledge representation efforts may move forward.