Theme

Knowledge philosophy quotes

Knowledge is the philosophical study of what we can justifiably claim to know—and where certainty ends.

Why this theme matters

Epistemology asks whether knowledge is justified true belief, reliable tracking of the world, or something else; it also asks how perception, testimony, memory, and reason contribute.

In the history of philosophy

From Plato’s dialogues and Indian pramāṇa theory to Descartes, Hume, Kant, and contemporary analytic epistemology, the theme remains a core branch of philosophy.

Thinkers in this collection

Socrates , Augustine of Hippo , Michel de Montaigne , René Descartes , Arthur Schopenhauer , William James , Auguste Comte , Albert Camus

Frequently asked questions

What is knowledge in philosophy?

A leading starting point is justified true belief, refined by debates about Gettier cases, reliability, evidence, and understanding.

How do philosophers distinguish knowledge from opinion?

By asking for reasons, methods, and standards of evidence that can survive scrutiny—not by intensity of conviction alone.

Where can I read philosophy quotes about knowledge?

This page collects English quotations on certainty, inquiry, ignorance, and the limits of knowing.

  1. What I do not know, I do not claim to know.
  2. No one errs willingly.
  3. What then is time? If no one asks me, I know; if I wish to explain it to one who asks, I do not know.
  4. What do I know?
  5. Once in a lifetime, everything must be doubted.
  6. The world is my representation.
  7. Believe that life is worth living, and your belief will help create the fact.
  8. To know, in order to foresee, so as to be able to act.
  9. Rebellion cannot do without the notion of a limit — it stops at human dignity.
  10. The Master said: You, shall I teach you what knowing is? To know what you know, and to know what you do not know — that is true knowing.
  11. One who knows others is wise; one who knows oneself is enlightened. One who conquers others has strength; one who conquers oneself is truly strong. One who knows contentment is rich; one who persists has will.
  12. Know the other and know yourself, and in a hundred battles you will not be in peril. Know yourself but not the other, and you will win one and lose one. Know neither, and you will be in peril in every battle.
    Sunzi
    School of Military Strategy
  13. Knowledge is the directing idea of action; action is the effort of knowledge. Knowledge is the beginning of action; action is the completion of knowledge.
  14. There has never been one who truly knows and yet does not act. If one knows but does not act, that is simply not yet knowing.
  15. Extend the innate good knowing.
  16. Of all things the measure is man.
  17. For knowledge itself is power.
  18. Whence has it all the materials of reason and knowledge? To this I answer, in one word, from experience.
  19. The true is precisely what is made.
  20. Knowledge without action is vanity, and action without knowledge is madness.
  21. Picture human beings as if living in an underground, cave-like dwelling.
  22. It is of the nature of reason to perceive things under a certain form of eternity.
  23. A wise man proportions his belief to the evidence.
  24. He who knows only his own side of the case, knows little of that.
  25. The quest for certainty…has always been a quest for a peace that is assured.
  26. Our knowledge can only be finite, while our ignorance must necessarily be infinite.
  27. The clearer the knowing, the more earnest the practice; the more earnest the practice, the clearer the knowing.
  28. To extend knowledge lies in investigating things: if one wishes to extend one's knowledge, one must approach things and exhaust their principle.
  29. That little bit of innate knowing of yours is your own criterion.
  30. To experience means to know facts just as they are.
  31. Doubt is not a pleasant condition, but certainty is an absurd one.
  32. All human beings by nature desire to know.
  33. Let us then suppose the mind to be, as we say, white paper, void of all characters.
  34. Three passions, simple but overwhelmingly strong, have governed my life: the longing for love, the search for knowledge, and unbearable pity for the suffering of mankind.
  35. The good life is one inspired by love and guided by knowledge.
  36. Knowing is the beginning of acting; acting is the completion of knowing.
  37. The true is the name of whatever proves itself to be good in the way of belief.
  38. Human knowledge and human power meet in one.
  39. Whatever is received is received according to the mode of the receiver.
  40. It is of great use to the sailor to know the length of his line, though he cannot with it fathom all the depths of the ocean.
  41. Everyone takes the limits of his own field of vision for the limits of the world.
  42. To teach how to live without certainty, and yet without being paralyzed by hesitation, is perhaps the chief thing that philosophy… can still do.
  43. You cannot speak of the ocean to a frog in a well — it is confined by its space.
  44. Know the other and know yourself, and in a hundred battles you will not be in peril.