Knowledge

Four words of ancient Greek are important to the first philosophical discussions of knowledge in the Western tradition. In a given context any of them might be translated with the word "knowledge": epistēmē, technē, mētis, and gnōsis.

Epistēmē names the most philosophical idea of knowledge: contemplative, disinterested, logical knowledge of truth and reality. Such knowledge is not merely true; it is self-certifying, indubitable, a rock-solid foundation on which to build scientific understanding. That was important. Philosophical thinking begins with the idea that belief or opinion (doxa) is not knowledge even if it happens to be true. Doxa is changeable, especially in a city, where people may be swayed by sophists and demagogues. Through its root (histēmi, "to stand firm, to set up"), epistēmē evokes ideas of firmness and stability. That is what the philosophers sought in the best and highest knowledge: an immovable point no persuasive speech can overturn.

Stoic philosophers defined epistēmē- knowledge as "apprehension (katalepsis) that is safe and unchangeable by argument," according to the Florilegium (extracts from Greek authors compiled by Joannes Stobaeus in the late fifth century). About two generations earlier, Plato (c. 428–348 or 347 B.C.E.) had put forward his highly influential vision of philosophical progress from doxa, the opinions of the crowd, to the correct opinion (orthodoxos) of specialists, and finally the summit, epistēmē, the best and highest knowledge. In the Theaetetus, what sets epistēmē apart from true opinion is called an aitias logismos, a reasoned account, explaining why the knowledge is and must be true. In the Republic, however, what sets epistēmē- knowledge apart from doxa is the object that it apprehends—a Form or Idea. Opinion cannot turn into knowledge because the "objects" of opinion are ultimately incoherent particulars for which no reasoned account is possible. Plato also explains how the Form of the Good is the cause of things being knowable at all. It is not the presence of a Form as such that makes epistēmē- knowledge possible; rather, it is the Form's place in the cosmic system. Form becomes logical and Ideas intelligible only when grasped in the light of the whole (the Good).

The philosophers did not invariably construe epistēmē as disinterested. The ordinary sense of the word is simply to have a good understanding of a thing, anything, archery, for instance. Aristotle (384–322 B.C.E.) divided epistēmē into three parts: theoretical (science and philosophy), practical (ethics, economics, politics), and productive, an epistēmē he called technē. Technē (from which technology, technique, and so on) refers to the knowledge of a recognized expert, like a physician, musician, or carpenter. Such knowledge is skillful, artful, reliable, specialized, and usually organized in professional associations. Plato explored the comparison of epistēmē and technē, using the words interchangeably in some dialogues. Could the best and highest knowing be some kind of art? One difficulty is that technē- knowledge aims at something concrete—a ship, a healthy human, a drama. The objects of philosophical epistēmē, however, are not these mundane artifacts, but the eternal Forms in which particulars merely participate. A further difficulty is that technē- knowledge can be used for good or ill alike. Such knowledge is instrumental, serving other ends, and the effectiveness of technique is no guarantee that the ends are good, whereas epistēmē is knowing in the light of the Good itself. This intrinsic value for knowledge of truth became traditional in Western thought, seldom questioned until Friedrich Wilhelm Nietzsche (1844–1900) at the end of the nineteenth century.

Mētis is cunning, clever, effective knowledge, as exemplified by the mythical figures of Odysseus and Daedalus. This knowledge combines flair and wisdom, subtlety and deception, resourcefulness and mastery of many skills. Far from disinterested or contemplative, it proves its value most concretely, especially in situations that are shifting or ambiguous, where art outweighs the force of violence. The philosophers either pass over the qualities of mētis- knowledge or mention them with hostile irony. Plato (in Gorgias and Philebus) condemns the in-exactitude, oblique procedures, cunning, and guesswork. Everything about mētis- knowledge confirms its limitation to the shadow theater Plato famously depicted our life as being. The philosopher seeks to penetrate those shadows to an immortal knowledge of the changeless Source of change.

Gnōsis usually has the sense of an intelligent grasp of a thing or situation. In the common account of Heracleitus (c. 540–c. 480 B.C.E.), Parmenides (515 B.C.E.), and Plato, only one who fully knows (gignōskein) can be sure to have grasped a thing as it veritably is. All that is required to transform this gnosis into the lauded philosophical epistēmē is the rational account by which we understand things in the light of the Good and the Whole. The so-called Gnostics were heretical sects of the early common era. They conceived of knowing as an immersion into the divine energy, to be possessed and transformed by it. The gnōsis sought by the Gnostics is an epignōsis, or knowledge of the self, its origin and destiny, a supernatural superknowledge that is supposed to save our lives.

The European Middle Ages divide into two parts, before and after about 1200. The thought of the first period is broadly Platonic, a legacy of St. Augustine (354–430). Later medieval thought benefited from the recovery of the works of Aristotle and the Islamic commentators. Augustine's outlook is notably Plato's: the senses depreciated in favor of immutable truths directly intuited, and a grudging admission of practical knowledge (technē) as a lower use of reason directed not toward wisdom but practical necessity. Human knowledge is possible because God illumines our minds, showing us the divine ideas, the archetypes of phenomena.

The most original, if not influential, medieval philosopher of knowledge is Rogen Bacon (c. 1214–c. 1292). Interested in problems that would occupy Galileo three hundred years later (especially falling bodies and optics), he anticipated the Italian astronomer's conviction that the solutions to these and other scientific problems lies in mathematics: "He who is ignorant of mathematics cannot know the other sciences nor the affairs of the world" (Opus majus 4.1). Even more against the scholastic grain was his enthusiasm for experiments: "He who wishes to rejoice without doubt in regard to the truths underlying phenomena must know how to devote himself to experiment" (Opus majus 4.1).

Thomas Aquinas (1225–1274) dominates the later period. He was the greatest of medieval Aristoteleans. Aristotle had argued that the object of the epistēmē-knowledge (scientia for Thomas) is immutable and necessary, incapable of being otherwise. Such knowledge is true and certain, being deduced from first principles. A thing is known when we learn its cause, and it is not known without the certainty of deduction from principles, confirming that the thing could not possibly be any other way. As John Buridan (c. 1300–1358) explains, "Science differs from opinion because … opinion does not judge with certainty but with fear and science judges with certainty and without fear" (Questions on the Nicomachean Ethics of Aristotle). This remains the view of practically all the European philosophers down to René Descartes and John Locke.