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popper and the pre-socratics

24 January 2004

The following book report is on an essay by Karl Popper entitled "The Beginnings of Rationalism," written in 1958 and published in "Popper: Selections" edited by David Miller.

As usual, non-quoted or bracketed material represents my efforts to stitch together and clarify an essay that's too long to present in its entirety. Now to Popper.

"The questions the pre-Socratics tried to answer were primarily cosmological questions, but there was also the question of the theory of knowledge. It is my belief that philosophy must return to cosmology and to a simple theory of knowledge. There is one philosophical problem in which all thinking men are interested: the problem of understanding the world in which we live; and thus ourselves (who are part of that world) and our knowledge of it."

"For me the interest of philosophy, no less than of science, lies solely in its bold attempt to add to our knowledge of the world, and to the theory of our knowledge of the world."

Popper says philosophy loses all interest for him when it specializes in a certain area and therefore "ceases to see and wonder at the riddles of our world. Specialization may be the great temptation for the scientist. For the philosopher is it a mortal sin."


"The history of Greek philosophy, especially the history from Thales to Plato, is a splendid story. It is almost too good to be true." It is to be contrasted with the normal idea of a "school."

"Far from being places of critical discussion [schools] make it their task to impart a definite doctrine, and to preserve it, pure and unchanged. It is the task of a school to hand on the tradition ... to keep the doctrine inviolate." He goes on to say that, "New ideas are heresies and lead to schisms."

"But the heretic claims, as a rule, that his is the true doctrine of the founder. ... he believes he is returning to the true orthodoxy which has somehow been perverted."

Popper says there can't be any rational discussion in a school of this kind, and he adds, "We could say that the character of Greek philosophy, and of the philosophical schools, is strikingly different from the dogmatic type of school here described."

He calls the Greek schools, "a unique phenomenon, and it is closely connected to the astonishing freedom and creativeness of Greek philosophy. ... If we look for the first signs of this new critical attitude, this new freedom of thought, we are lead to Anaximander's criticism of Thales. ... This suggests I think that it was Thales who founded the new tradition of freedom — based upon a new relation between master and pupil — he seems to have been able to tolerate criticism. And what's more, he seems to have created the tradition that one ought to tolerate criticism."

"I like to think that Thales was the first teacher who said to his pupils: 'This is how I see things — how I believe that things are. Try to improve upon my teaching.' ... At any rate there is the historical fact that the Ionian school was the first in which pupils criticized their masters, in one generation after another."

"It was a momentous innovation. It meant a break with the dogmatic tradition which permits only one school doctrine, and the introduction in its place of a tradition that admits a plurality of doctrines which all try to approach the truth by means of critical discussion. It thus leads, almost by necessity, to the realization that our attempts to see and to find the truth are not final, but open to improvement; that our knowledge, our doctrine, is conjectural; that it consists of guesses, of hypotheses, rather than of final and certain truths; and that criticism and discussion are our only means of getting nearer to the truth."

He says that even wild innovation is encouraged because it can be controlled by critical examination. One is free to dream up strange explanations, for the other part of the process always brings us back to reality.


"I now come to my central contention. It is this. The rationalist tradition, the tradition of critical discussion, represents the only practicable way of expanding our knowledge — conjectural or hypothetical knowledge, of course. There is no other way."

"According to the theory of knowledge here outlined there are in the main only two ways in which theories may be superior to others: they may explain more; and they may be better tested — that is, they may be more fully and critically discussed, in the light of all we know, of all the objections we can think of, and especially in the light of observational or experimental tests which were designed with the aim of criticizing the theory."

He says our theories are guesswork and that the only element of rationality in our attempts to know the world comes in the critical examination of our theories. "If you ask me, 'How do you know?' my reply would be, 'I don't; I only propose a guess.'"

"Two of the greatest men who clearly .... understood what I regard as the true theory of knowledge [guess and check] were Galileo and Einstein. Yet the ancients also knew it. Incredible as it sounds, we find a clear recognition and formulation of this theory of rational knowledge almost immediately after the practice of critical discussion began. Our oldest extant fragments in this field are those of Xenophanes. I will present here five of them in an order that suggests the boldness of his attack and the gravity of his problems which made him conscious of the fact that all our knowledge is guesswork.

"The Ethiops say that their gods are flat-nosed and black
While the Thracians say that theirs have blue eyes and red hair."

"Yet if cattle or horses or lions had hands and could draw
And could sculpture like men, then the horses would draw their god like horses, and cattle like cattle, and each would then shape bodies of gods in the likeness, each kind, of its own."

"The gods did not reveal, from the beginning,
All things to us, but in the course of time
Through seeking we may learn and know things better.

"These things are, we conjecture, like the truth."

"But as for certain truth, no man has known it,
Nor shall he know it, neither of the gods
Nor yet of all the things of which I speak.
And even if by chance he were to utter
The final truth, he would himself not know it:
For all is but a woven web of guesses."

Popper then quotes two passages by Heraclitus:

"It is not in the nature or character of man to possess true knowledge, though it is in the divine nature ... He who does not expect the unexpected will not detect it; for him it will remain undetectable, and unapproachable."

And one from Democritus:

"But in fact, nothing do we know from having see it; for the truth is hidden in the deep." [This seems to prefigure the whole thrust of Kant.]

Popper closes his essay with a short paragraph:

"This is how the critical attitude of the pre-Socratics foreshadowed, and prepared for, the ethical rationalism of Socrates: his belief that the search for truth through critical discussion was a way of life — the best he knew."

See also —



“Great doubt: great awakening. Little doubt: little awakening.
No doubt: no awakening.” — Zen proverb