Top 70 Charles Sanders Peirce Quotes (2025 Update)

1. “The entire universe is perfused with signs, if it is not composed exclusively of signs.”

— Charles Sanders Peirce

2. “It is not knowing, but the love of learning, that characterizes the scientific man.”

— Charles Sanders Peirce

3. “Every new concept first comes to the mind in a judgment.”

— Charles Sanders Peirce

4. “The idea does not belong to the soul; it is the soul that belongs to the idea.”

— Charles Sanders Peirce

5. “Bad reasoning as well as good reasoning is possible; and this fact is the foundation of the practical side of logic.”

— Charles Sanders Peirce

6. “My language is the sum total of myself.”

— Charles Sanders Peirce

7. “The pragmatist knows that doubt is an art which hs to be acquired with difficulty.”

— Charles Sanders Peirce

8. “Effort supposes resistance.”

— Charles Sanders Peirce

9. “There is a kink in my damned brain that prevents me from thinking as other people think.”

— Charles Sanders Peirce

10. “We do not really think, we are barely conscious, until something goes wrong.”

— Charles Sanders Peirce

11. “All the greatest achievements of mind have been beyond the power of unaided individuals.”

— Charles Sanders Peirce

12. “There never was a sounder logical maxim of scientific procedure than Ockham’s razor: Entia non sunt multiplicanda praeter necessitatem. That is to say; before you try a complicated hypothesis, you should make quite sure that no simplification of it will explain the facts equally well.”

— Charles Sanders Peirce

13. “The opinion which is fated to be ultimately agreed to by all who investigate, is what we mean by the truth, and the object represented in this opinion is the real. That is the way I would explain reality.”

— Charles Sanders Peirce

14. “I define a Sign as anything which is so determined by something else, called its Object, and so determines an effect upon a person, which effect I call its Interpretant, that the latter is thereby mediately determined by the former.”

— Charles Sanders Peirce

15. “And what, then, is belief? It is the demi-cadence which closes a musical phrase in the symphony of our intellectual life.”

— Charles Sanders Peirce

16. “True science is distinctively the study of useless things. For the useful things will get studied without the aid of scientific men. To employ these rare minds on such work is like running a steam engine by burning diamonds.”

— Charles Sanders Peirce

17. “Some think to avoid the influence of metaphysical errors, by paying no attention to metaphysics; but experience shows that these men beyond all others are held in an iron vice of metaphysical theory, because by theories that they have never called in question.”

— Charles Sanders Peirce

18. “The method of authority will always govern the mass of mankind; and those who wield the various forms of organized force in the state will never be convinced that dangerous reasoning ought not to be suppressed in some way.”

— Charles Sanders Peirce

19. “The definition of definition is at bottom just what the maxim of pragmatism expresses.”

— Charles Sanders Peirce

20. “Every man is fully satisfied that there is such a thing as truth, or he would not ask any question.”

— Charles Sanders Peirce

21. “It is a common observation that a science first begins to be exact when it is quantitatively treated. What are called the exact sciences are no others than the mathematical ones.”

— Charles Sanders Peirce

22. “Doubt is an uneasy and dissatisfied state from which we struggle to free ourselves and pass into the state of belief; while the latter is a calm and satisfactory state which we do not wish to avoid, or to change to a belief in anything else.”

— Charles Sanders Peirce

23. “Abduction is the process of forming an explanatory hypothesis. It is the only logical operation which introduces any new idea; for induction does nothing but determine a value and deduction merely evolves the necessary consequences of a pure hypothesis.”

— Charles Sanders Peirce

24. “The woof and warp of all thought and all research is symbols, and the life of thought and science is the life inherent in symbols; so that it is wrong to say that a good language is important to good thought, merely; for it is the essence of it.”

— Charles Sanders Peirce

25. “All the evolution we know of proceeds from the vague to the definite.”

— Charles Sanders Peirce

26. “It is certain that the only hope of retroductive reasoning ever reaching the truth is that there may be some natural tendency toward an agreement between the ideas which suggest themselves to the human mind and those which are concerned in the laws of nature.”

— Charles Sanders Peirce

27. “Unless man have a natural bent in accordance with nature’s, he has no chance of understanding nature at all.”

— Charles Sanders Peirce

28. “Generality is, indeed, an indispensable ingredient of reality; for mere individual existence or actuality without any regularity whatever is a nullity. Chaos is pure nothing.”

— Charles Sanders Peirce

29. “But the extraordinary insight which some persons are able to gain of others from indications so slight that it is difficult to ascertain what they are, is certainly rendered more comprehensible by the view here taken.”

— Charles Sanders Peirce

30. “We cannot begin with complete doubt.”

— Charles Sanders Peirce

31. “The universe ought to be presumed too vast to have any character.”

— Charles Sanders Peirce

32. “The essence of belief is the establishment of a habit; and different beliefs are distinguished by the different modes of action to which they give rise.”

— Charles Sanders Peirce

33. “It has never been in my power to study anything, mathematics, ethics, metaphysics, gravitation, thermodynamics, optics, chemistry, comparative anatomy, astronomy, psychology, phonetics, economics, the history of science, whist, men and women, wine, metrology, except as a study of semeiotic .”

— Charles Sanders Peirce

34. “Every work of science great enough to be well remembered for a few generations affords some exemplification of the defective state of the art of reasoning of the time when it was written; and each chief step in science has been a lesson in logic.”

— Charles Sanders Peirce

35. “Law is par excellence the thing that wants a reason. Now the only possible way of accounting for the laws of nature, and for uniformity in general, is to suppose them results of evolution.”

— Charles Sanders Peirce

36. “Consider what effects that might conceivably have practical bearings you conceive the objects of your conception to have. Then, your conception of those effects is the whole of your conception of the object.”

— Charles Sanders Peirce

37. “We, one and all of us, have an instinct to pray; and this fact constitutes an invitation from God to pray.”

— Charles Sanders Peirce

38. “The a priori method is distinguished for its comfortable conclusions. It is the nature of the process to adopt whatever belief weare inclined to, and there are certain flatteries to the vanity of man which we all believe by nature, until we are awakened from our pleasing dream by rough facts.”

— Charles Sanders Peirce

39. “We think only in signs.”

— Charles Sanders Peirce

40. “If an opinion can eventually go to the determination of a practical belief, it, in so far, becomes itself a practical belief; and every proposition that is not pure metaphysical jargon and chatter must have some possible bearing upon practice.”

— Charles Sanders Peirce

41. “Few persons care to study logic, because everybody conceives himself to be proficient enough in the art of reasoning already. But I observe that this satisfaction is limited to one’s own ratiocination, and does not extend to that of other men.”

— Charles Sanders Peirce

42. “Another characteristic of mathematical thought is that it can have no success where it cannot generalize.”

— Charles Sanders Peirce

43. “There is not a single truth of science upon which we ought to bet more than about a million of millions to one.”

— Charles Sanders Peirce

44. “Theoretically, I grant you, there is no possibility of error in necessary reasoning. But to speak thus “theoretically,” is to uselanguage in a Pickwickian sense. In practice, and in fact, mathematics is not exempt from that liability to error that affects everything that man does.”

— Charles Sanders Peirce

45. “In all the works on pedagogy that ever I read – and they have been many, big, and heavy – I don’t remember that any one has advocated a system of teaching by practical jokes, mostly cruel. That, however, describes the method of our great teacher, Experience.”

— Charles Sanders Peirce

46. “The difference between a pessimistic and an optimistic mind is of such controlling importance in regard to every intellectual function, and especially for the conduct of life, that it is out of the question to admit that both are normal, and the great majority of mankind are naturally optimistic.”

— Charles Sanders Peirce

47. “One will meet, for example, the virtual assumption that what is relative to thought cannot be real. But why not, exactly? Red is relative to sight, but the fact that this or that is in that relation to vision that we call being red is not itself relative to sight; it is a real fact.”

— Charles Sanders Peirce

48. “Third, consider the insistency of an idea. The insistency of a past idea with reference to the present is a quantity which is less, the further back that past idea is, and rises to infinity as the past idea is brought up into coincidence with the present.”

— Charles Sanders Peirce

49. “Whenever a man acts purposively, he acts under a belief in some experimental phenomenon. Consequently, the sum of the experimental phenomena that a proposition implies makes up its entire bearing upon human conduct.”

— Charles Sanders Peirce

50. “Our whole past experience is continually in our consciousness, though most of it sunk to a great depth of dimness. I think of consciousness as a bottomless lake, whose waters seem transparent, yet into which we can clearly see but a little way.”

— Charles Sanders Peirce