Logic as a Tool

Introduction

What is logic about? What does it study and what does it offer? A usual definition found in the encyclopedia is that it is the branch of philosophy that studies the laws and rules of human reasoning. Little of this is actually correct. First, logic left the cradle of philosophy long ago and is now a truly interdisciplinary area, related and relevant not only to philosophy but also to mathematics, computer science, artificial intelligence, linguistics, social sciences, and even economics. Second, is logic really about how we reason? If that were the case, as a professional logician for many years I should already know quite well how exactly humans reason. Alas, the more experience I gain in life, the less I understand that. One thing is certain: most people use in their everyday reasoning emotions, analogies, clichés, ungrounded beliefs and superstitions, that is, everything but logic. But then, maybe logic studies the reasoning of the rational human, for whom reasoning is a purely rational brain activity? Well, while many (but far from all) of us humans reason with their brains, this is not sufficient to understand how we do it. As the American scientist Emerson M. Pugh brilliantly put it: “If the human brain were so simple that we could understand it, we would be so simple that we couldn't.”

What does logic tell us, after all, if not how we reason? A better answer is: it tells us how we can – and ideally should – reason in a systematic and well-structured way that ...