Comparison. That's the essence of the mind. Whenever we think or perceive something, we are making comparisons. When we look at an apple, we identify it as an apple because we compare it with everything surrounding the apple. When we look at an apple and an orange, we are comparing and contrasting them in order to determine what is an "apple" and an "orange". When we analize cause and effect, we are comparing something in terms of time- what it was before and what it is now. All logic comes down to comparison. From comparisons come all the logical subjects such as epistemology, semantics, etc. So why don't we use a logic system based specifically on comparison?