Was it Plato or Aristotle? I don't need to be told that logic was an evolution that was merely advanced by these two Greeks. But who really gave us the rules of the game? I've read some of Plato. Not much, but from his dialogues I gather more ethics and "what does what mean" sort of games rather than any formal system of logic. Aristotle explicity gives us rules and methodoloy. So my primtive answer is that Aristotle "invented" logic, Plato was merely an expert in applying it. This being a philosophy forum... I don't want things getting side tracked hehe. So lets assume Socrates and all the pre-Socratic philosophers contributions were minimal as they left little written work. I repeat, lets assume.