The very first lesson of logic

The very first lesson that we have a right to demand that logic shall teach us is, how to make our ideas clear; and a most important one it is, depreciated only by minds who stand in need of it. To know what we think, to be masters of your own meaning, will make a solid foundation for great and weighty thought.(Charles Sanders Peirce, How to Make Our Ideas Clear)

In the fifth century B.C., Socrates stirred up some of the deepest controversies by claiming to know very little, if anything. By his relentless questioning, he destroyed the smug self-satifaction of people who claimed to have knowledge of fundamental subjects like Truth, Beauty, Virtue, and Justice. By recreating Socrates’ dialectical process of questioning, his student Plato established the subject of epistemology– the study of the nature of knowledge and its justification. Epistemology, in those days, was literally a matter of life and death. For his alleged impiety in questioning cherished beliefs, Socrates was condemned to death as a corrupter of the morals of Athenian youth.

Plato’s student Aristotle shifted the emphasis of philosophy from the nature of knowledge to the less controversial, but more practical problem of representing knowledge. His monumental life’s work resulted in an encyclopedic edge, Aristotle had to invent the words for representing it. He established the initial terminology and defined the scope of logic, physics, metaphysics, biology, psychology, linguistics, politics, ethics, rhetoric, and economics. For all those fields, the terms that he either coined or adopted have become the core of today’s international technical vocabulary. Some of them, such as category, metaphor, and hypothesis, are direct borrowings from Aristotle’s Greek. Others, such as quantity, quality, genus, species, noun, verb, subject, and predicate, are borrowings of Latin words that were coined for the purpose of translating the Greek. The English word quality, for example, comes from Cicero’s word qualitas. Cicero explained that he coined the word as a translation of the Greek poiot (what-kind-ness), which “among the Greeks is not a word of the common people, but of the philosophers”. Today Aristotle’s words have been so thoroughly absorbed into English that category is a common term on TV quiz shows and quality is more often used by salesmen than by philosophers.