Digital Companion to C. S. Peirce
1873 | Chapter V. That the significance of thought lies in its reference to the future | W 3:107-8; CP 7.359-60

A belief is an habitual connection of ideas. For example, to say that I believe prussic acid is a poison is to say that when the idea of drinking it occurs to me, the idea of it as a poison with all the other ideas which follow in the train of this will arise in my mind. Among these ideas, or objects present to me, is the sense of refusing to drink it. This, if I am in a normal condition, will be followed by an action of the nerves when needed which will remove the cup from my lips. It seems probable that every habitual connection of ideas may produce such an effect upon the will. If this is actually so, a belief and an habitual connection of ideas are one and the same.

In a mind which is capable of logical criticism of its beliefs, there must be a sensation of believing, which shall serve to show what ideas are connected. [—] The intellectual significance of beliefs lies wholly in the conclusions which may be drawn from them, and ultimately in their effects upon our conduct. For there does not seem to be any important distinction between two propositions which never can yield different practical results.

1877 | The Fixation of Belief | CP 5.370-375

We generally know when we wish to ask a question and when we wish to pronounce a judgment, for there is a dissimilarity between the sensation of doubting and that of believing.

But this is not all which distinguishes doubt from belief. There is a practical difference. Our beliefs guide our desires and shape our actions. The Assassins, or followers of the Old Man of the Mountain, used to rush into death at his least command, because they believed that obedience to him would insure everlasting felicity. Had they doubted this, they would not have acted as they did. So it is with every belief, according to its degree. The feeling of believing is a more or less sure indication of there being established in our nature some habit which will determine our actions. Doubt never has such an effect.

Nor must we overlook a third point of difference. 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. On the contrary, we cling tenaciously, not merely to believing, but to believing just what we do believe.

Thus, both doubt and belief have positive effects upon us, though very different ones. Belief does not make us act at once, but puts us into such a condition that we shall behave in some certain way, when the occasion arises. Doubt has not the least such active effect, but stimulates us to inquiry until it is destroyed. This reminds us of the irritation of a nerve and the reflex action produced thereby; while for the analogue of belief, in the nervous system, we must look to what are called nervous associations – for example, to that habit of the nerves in consequence of which the smell of a peach will make the mouth water.

The irritation of doubt causes a struggle to attain a state of belief. I shall term this struggle Inquiry, though it must be admitted that this is sometimes not a very apt designation.

[—] Hence, the sole object of inquiry is the settlement of opinion. We may fancy that this is not enough for us, and that we seek, not merely an opinion, but a true opinion. But put this fancy to the test, and it proves groundless; for as soon as a firm belief is reached we are entirely satisfied, whether the belief be true or false. And it is clear that nothing out of the sphere of our knowledge can be our object, for nothing which does not affect the mind can be the motive for mental effort. The most that can be maintained is, that we seek for a belief that we shall think to be true. But we think each one of our beliefs to be true, and, indeed, it is mere tautology to say so.

1878 | How to Make Our Ideas Clear | CP 5.394

… the action of thought is excited by the irritation of doubt, and ceases when belief is attained; so that the production of belief is the sole function of thought. All these words, however, are too strong for my purpose. It is as if I had described the phenomena as they appear under a mental microscope. Doubt and Belief, as the words are commonly employed, relate to religious or other grave discussions. But here I use them to designate the starting of any question, no matter how small or how great, and the resolution of it.

1878 | How to Make Our Ideas Clear | CP 5.397-8; W 3:263-4

And what, then, is belief? It is the demi-cadence which closes a musical phrase in the symphony of our intellectual life. We have seen that it has just three properties: First, it is something that we are aware of; second, it appeases the irritation of doubt; and, third, it involves the establishment in our nature of a rule of action, or, say for short, a habit. As it appeases the irritation of doubt, which is the motive for thinking, thought relaxes, and comes to rest for a moment when belief is reached. But, since belief is a rule for action, the application of which involves further doubt and further thought, at the same time that it is a stopping-place, it is also a new starting-place for thought. That is why I have permitted myself to call it thought at rest, although thought is essentially an action. The final upshot of thinking is the exercise of volition, and of this thought no longer forms a part; but belief is only a stadium of mental action, an effect upon our nature due to thought, which will influence future thinking.

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. If beliefs do not differ in this respect, if they appease the same doubt by producing the same rule of action, then no mere differences in the manner of consciousness of them can make them different beliefs, any more than playing a tune in different keys is playing different tunes.

1880 | On the Algebra of Logic | W 4:164; CP 3.160

A cerebral habit of the highest kind, which will determine what we do in fancy as well as what we do in action, is called a belief.

1893 | Grand Logic 1893: Division III. Substantial Study of Logic Chapter VI. The Essence of Reasoning | MS [R] 408:146

a belief is a controlled habit. Being formed, or continued, under control, there is an expectation and hope that it will last. Under the rational method of fixing belief, there is a hope that all men and rational beings will come to it, or would come to it, with sufficient workings of life.

1895 | Short Logic | EP 2:12

A Belief is a state of mind of the nature of a habit, of which the person is aware, and which, if he acts deliberately on a suitable occasion, would induce him to act in a way different from what he might act in the absence of such habit.

[—] If a man really believes that alcohol is injurious to him and does not choose to injure himself, but still drinks for the sake of the momentary satisfaction, then he is not acting deliberately. But a habit of which we are not aware, or with which we are not deliberately satisfied, is not a belief.

An act of consciousness in which a person thinks he recognizes a belief is called a judgement. The expression of a judgement is called in logic a proposition.

1898 | Cambridge Lectures on Reasoning and the Logic of Things: Philosophy and the Conduct of Life | CP 1.635

Hence, I hold that what is properly and usually called belief, that is, the adoption of a proposition as a {ktéma es aei} to use the energetic phrase of Doctor Carus, has no place in science at all. We believe the proposition we are ready to act upon. Full belief is willingness to act upon the proposition in vital crises, opinion is willingness to act upon it in relatively insignificant affairs. But pure science has nothing at all to do with action. The propositions it accepts, it merely writes in the list of premisses it proposes to use. Nothing is vital for science; nothing can be. Its accepted propositions, therefore, are but opinions at most; and the whole list is provisional. The scientific man is not in the least wedded to his conclusions.

1901 | Hume's Argument against Miracles, and the Idea of Natural Law (Hume) | MS [R] 873:4 (var.); HP 2:912

A state of belief in a proposition is such a state that the believer would on every pertinent occasion act according to the logical consequence of that proposition, He has a habit, and the proposition describes in abstract terms what sort of a habit it is. But for genuine belief, the man must not only have the habit, but must be aware of having it, and must be fully satisfied with having it. I will not say that no more than that is involved in saying that a man believes a proposition, but I think we may say that that constitutes practical belief.

1902 | Carnegie Institution Correspondence | NEM 4:39-40

I use the word belief to express any kind of holding for true or acceptance of a proposition. Belief, in this sense, is a composite thing. Its principal element is not a matter of consciousness at all; but is a habit established in the believer’s nature, in consequence of which he would act, should occasion present itself, in ceratin ways. However, not every habit is a belief. A belief is a habit with which the believer is deliberately satisfied. This implies that he is aware of it, and being aware of it does not struggle against it. A third important characteristic of belief is that while other habits are contracted by repeatedly performing the act under the conditions, belief may be, and commonly if not invariably is contracted, by merely imagining the situation and imagining what would be our experience and what our conduct in such a situation; and this mere imagination at once establishes such a habit that if the imagined case were realized we should really behave in that way.

1902 | Minute Logic: Chapter II. Section II. Why Study Logic? | CP 2.148

For our present purpose it is sufficient to say that the inferential process involves the formation of a habit. For it produces a belief, or opinion; and a genuine belief, or opinion, is something on which a man is prepared to act, and is therefore, in a general sense, a habit. A belief need not be conscious. When it is recognized, the act of recognition is called by logicians a judgment, although this is properly a term of psychology. A man may become aware of any habit, and may describe to himself the general way in which it will act. For every habit has, or is, a general law. Whatever is truly general refers to the indefinite future; for the past contains only a certain collection of such cases that have occurred. The past is actual fact. But a general (fact) cannot be fully realized. It is a potentiality; and its mode of being is esse in futuro. The future is potential, not actual. What particularly distinguishes a general belief, or opinion, such as is an inferential conclusion, from other habits, is that it is active in the imagination. If I have a habit of putting my left leg into my trouser before the right, when I imagine that I put on my trousers, I shall probably not definitely think of putting the left leg on first. But if I believe that fire is dangerous, and I imagine a fire bursting out close beside me, I shall also imagine that I jump back. Conversely - and this is the most important point - a belief-habit formed in the imagination simply, as when I consider how I ought to act under imaginary circumstances, will equally affect my real action should those circumstances be realized. Thus, when you say that you have faith in reasoning, what you mean is that the belief-habit formed in the imagination will determine your actions in the real case. This is looking upon the matter from the psychological point of view. Under a logical aspect your opinion in question is that general cognitions of potentialities in futuro, if duly constructed, will under imaginary conditions determine schemata or imaginary skeleton diagrams with which percepts will accord when the real conditions accord with those imaginary conditions; or, stating the essence of the matter in a nutshell, you opine that percepts follow certain general laws.

1903 | Harvard Lectures on Pragmatism: Lecture I | CP 5.27-28

What is the proof that the possible practical consequences of a concept constitute the sum total of the concept? The argument upon which I rested the maxim in my original paper was that belief consists mainly in being deliberately prepared to adopt the formula believed in as the guide to action. If this be in truth the nature of belief, then undoubtedly the proposition believed in can itself be nothing but a maxim of conduct. That I believe is quite evident.

But how do we know that belief is nothing but the deliberate preparedness to act according to the formula believed?

My original article carried this back to a psychological principle. The conception of truth, according to me, was developed out of an original impulse to act consistently, to have a definite intention. But in the first place, this was not very clearly made out, and in the second place, I do not think it satisfactory to reduce such fundamental things to facts of psychology.

1903 | Harvard Lectures on Pragmatism: Lecture II | CP 5.60

But you will mark the limitation of my approval of Ockham’s razor. It is a sound maxim of scientific procedure. If the question be what one ought to believe, the logic of the situation must take other factors into account. Speaking strictly, belief is out of place in pure theoretical science, which has nothing nearer to it than the establishment of doctrines, and only the provisional establishment of them, at that. Compared with living belief it is nothing but a ghost. If the captain of a vessel on a lee shore in a terrific storm finds himself in a critical position in which he must instantly either put his wheel to port acting on one hypothesis, or put his wheel to starboard acting on the contrary hypothesis, and his vessel will infallibly be dashed to pieces if he decides the question wrongly, Ockham’s razor is not worth the stout belief of any common seaman. For stout belief may happen to save the ship, while Entia non sunt multiplicanda praeter necessitatem would be only a stupid way of spelling Shipwreck. Now in matters of real practical concern we are all in something like the situation of that sea-captain.

1903 | Telepathy | CP 7.606

But in science instinct can play but a secondary rôle. The reason of this is that our instincts are adapted to the continuance of the race and thus to individual life. But science has an indefinite future before it; and what it aims at is to gain the greatest possible advance in knowledge in five centuries or ten. Instinct not being adapted to this purpose, the methods of science must be artificial. As Professor Trowbridge hints, pure science has nothing to do with belief. What I believe is what I am prepared to go on today. Imagine a general besieging a city. He sits in his tent at night preparing the details of his plan of action for the morrow. He finds that what his orders ought to be and perhaps the whole fate of his army depend upon a certain question of topography concerning which he is in need of information. He sends for his best engineer officer, – a highly scientific man, – and asks how he is to ascertain the fact in question. The officer replies, “There is only one possible way of ascertaining that. So and so must be done.” “How long will that take?” “Two or three months.” The general dismisses the man of science, – as Napoleon dismissed Laplace, – and sends for another officer, not half so scientific, but good at guessing. What this officer shall say, the general will go by. He will adopt it as his belief.

1904 | New Elements (Kaina stoiceia) | EP 2:312

A belief in a proposition is a controlled and contented habit of acting in ways that will be productive of desired results only if the proposition is true.

1904 | Sketch of Dichotomic Mathematics | NEM 4:297-8

Belief does not principally consist in any particular act of thought, but in a habit of thought and a conduct. A man does not necessarily believe what he thinks he believes. He only believes what he deliberately adopts and is ready to make a habit of conduct.

1905 | What Pragmatism Is | CP 5.417

Belief is not a momentary mode of consciousness; it is a habit of mind essentially enduring for some time, and mostly (at least) unconscious; and like other habits, it is (until it meets with some surprise that begins its dissolution) perfectly self-satisfied. Doubt is of an altogether contrary genus. It is not a habit, but the privation of a habit. Now a privation of a habit, in order to be anything at all, must be a condition of erratic activity that in some way must get superseded by a habit.

1907 | Pragmatism | CP 5.12

In particular, he [Nicholas St. John Green] often urged the importance of applying Bain’s definition of belief, as “that upon which a man is prepared to act.” From this definition, pragmatism is scarce more than a corollary; so that I am disposed to think of him as the grandfather of pragmatism.

1907 | Pragmatism | CP 5.480

[Readiness] to act in a certain way under given circumstances and when actuated by a given motive is a habit; and a deliberate, or self-controlled, habit is precisely a belief.

1907 | The Fourth Curiosity | MS [R] 200:91

…as a pragmaticist I hold a belief to be a determination of a person such that under certain conceivable experiential circumstances he would be led by it to act in a certain way, this determination being usually accompanied by a feeling or a particular quality called a feeling of belief, as well as by special feelings associated with the particular characters of the determination.

1911 | A Logical Critique of Essential Articles of Religious Faith | MS [R] 852:9-10

A negative doubt is the mere absence of a state of Belief, that is to say, of a habit of determinate expectation under definite circumstances. More generally, a Belief is self-controlled Habit.

1911 | Letter to J. H. Kehler | NEM 3:191; MS [R] 764

believing, real genuine belief, consists in a habit with which one is contented and which one usually recognizes (though not always)[,], this habit consisting in the general fact that under certain circumstances one would act in a definite way, and would be content to do so.