Logic, strictly speaking, is the science or study of how to evaluate arguments and reasoning. Logic is what allows us to distinguish correct reasoning from poor reasoning. Logic is important because it helps us reason correctly — without correct reasoning, we don’t have a viable means for knowing the truth or arriving at sound beliefs.

Logic is not a matter of opinion: when it comes to evaluating arguments, there are specific principles and criteria which should be used. If we use those principles and criteria, then we are using logic; if we aren’t using those principles and criteria, then we are not justified in claiming to use logic or be logical. This is important because sometimes people don’t realize that what sounds reasonable isn’t necessarily logical.

The Greek philosopher Aristotle is generally regarded as the “father” of logic. Others before him discussed the nature of arguments and how to evaluate them, but he was the one who first created systematic criteria for doing it. His conception of syllogistic logic remains a cornerstone of the study of logic even today. Others who have played important roles in the development of logic include Peter Abelard, William of Occam, Wilhelm Leibniz, Gottlob Frege, Kurt Goedel, and John Venn.

Logic sounds like an esoteric subject for academic philosophers, but the truth of the matter is that logic is applicable anywhere that reasoning and arguments are being used. Whether the actual subject matter is politics, ethics, social policies, raising children, or organizing a book collection, we use reasoning and arguments to arrive at specific conclusions. If we don’t apply the criteria of logic to our arguments, we cannot trust that our reasoning is sound.