James’ Principles of Psychology

William James The Principles of Psychology, Henry Holt and Co. Ltd, 1890

A one-time classic, credited with making psychology more scientific, and still regarded as insightful. It predates his work on pragmatism, which is also still highly rated. I pull out those relevant to uncertainty and complexity.

The final chapter is on logic and maths:

XXVIIL Necessary Truths – Effects of Experience

Mathematical Relations

… The other couplings of data which pass for a priori necessities of thought [include] the mathematical judgments … . [These]  express results of comparison and nothing more. The mathematical sciences deal with similarities and equalities exclusively, and not with coexistences and sequences. Hence they have, in the first instance, no connection with the order of experience. …

   Arithmetic and its fundamental principles are thus independent of our experiences or of the order of the world. The matter of arithmetic is mental matter; its principles flow from the fact that the matter forms a series, which can be cut into by us wherever we like without the matter changing.

Consciousness of Series Is the Basis of Rationality

   Classification, logic, and mathematics all result, then, from the mere play of the mind comparing its conceptions, no matter whence the latter may have come. The essential condition for the formation of all these sciences is that we should have grown capable of apprehending series as such, and of distinguishing them as homogeneous or heterogeneous, and as possessing definite directions of what I have called increase. This consciousness of series is a human perfection which has been gradually evolved, and which varies greatly from man to man. There is no accounting for it as a result of habitual associations among outward impressions, so we must simply ascribe it to the factors, whatever they be, of inward cerebral growth. Once this consciousness attained to, however, mediate thought be comes possible ; with our very awareness of a series may go an awareness that dropping terms out of it will leave identical relations between the terms that remain ; and thus arises a perception of relations between things so naturally separate that we should otherwise never have compared them together at all.

There is thus no denying the fact that the mind is filled with necessary and eternal relations which it finds between certain of its ideal conceptions, and, which form a determinate system, independent of the order of frequency in which experience may have associated the conception s originals in time and space.

But what are these eternal verities, these agreements, which the mind discovers by barely considering its own fixed meanings, except what I have said ? relations of like ness and difference, immediate or mediate, between the terms of certain series. Classification is serial comparison, logic mediate subsumption, arithmetic mediate equality of different bundles of attention-strokes, geometry mediate equality of different ways of carving space. None of these eternal verities has anything to say about facts, about what is or is not in the world. Logic does not say whether Socrates, men, mortals or immortals exist; arithmetic does not tell us where her 7 s, 5 s, and 12 s are to be found; geometry affirms not that circles and rectangles are real. All that these sciences make us sure of is, that if these things are anywhere to be found, the eternal verities will obtain of them.  Locke accordingly never tires of telling us [Essay concerning Human Understanding, book IV, chaps IX, VII.] that the universal propositions of whose truth or falsehood we can have certain knowledge, concern not existence. . . . These universal and self-evident principles, being only our constant, clear, and distinct knowledge of our own ideas more general or comprehensive, can assure us of nothing that passes without the mind; their certainty is founded only upon the knowledge of each idea by itself, and of its distinction from others; about which we cannot be mistaken whilst they are in our minds. . . . The mathematician considers the truth and properties belonging to a rectangle or circle only as they are in idea in his own mind. For it is possible he never found either of them existing mathematically, i.e., precisely true, in his life. But yet the knowledge he has of any truths or properties belonging to a circle, or any other mathematical figure, are nevertheless true and certain even of real things existing; because real things are no farther concerned nor intended to be meant by any such propositions, than as things really agree to those archetypes in his mind. Is it true of the idea of a triangle, that its three angles are equal to two right ones ? It is true also of a triangle wherever it really exists. Whatever other figure exists that is not exactly answerable to that idea in his mind is not at all concerned in that proposition. And therefore he is certain all his knowledge concerning such ideas is real knowledge: because, intending things no farther than they agree with those his ideas, he is sure what he knows concerning those figures when they have barely an ideal existence in his mind will hold true of them also when they have a real existence in matter. ” But “that any or what bodies do exist, that we are left to our senses to discover to us as far as they can.”

My Comments

Wikipedia has:

Mathematics (from Greek μάθημα máthēma, “knowledge, study, learning”) is the study of such topics as quantity,[1]structure,[2]space,[1] and change.[3][4][5] There are many views among mathematicians and philosophers as to the exact scope and definition of mathematics.[6][7]

It is not immediately clear if Wikipedia means real space or some conceptual space, and following the links does not resolve the ambiguity. One might be forgiven for thinking that the difference does not matter: the map ‘is’ the territory. Yet James (and before him Locke) point out that mathematics can either be strictly logical or it can be about real quantities etc, but not both. As I understand it, the mainstream mathematical view, then as now, is that mathematics strives to be logical. In James’ time it hadn’t entirely succeeded, but had already recognized the need to shed any pretence at realism. Thus something else – such as science – is required to link mathematics to ‘reality’.

James’ view, which sought to set psychology on a scientific basis, is in contrast to some contemporary psychologists’ views, which is that mathematics, like all else, is socially constructed. That is, mathematics is whatever people think it is, and if people believe it to be both about reality and to have the reliability of a sound logic, then so it is ‘for them’. In behavioural economics, for example, people are held to have biases not because what they are doing is ill-advised in any logical sense, but because it conflicts with what behavioural psychologists hold to be rational in their socially constructed sense. (Actually, I am not sure that these psychologists have thought about it at all deeply, but this seems to be what they would need to believe in order to justify what they espouse.)

After James, Einstein and Eddington showed that light does not travel in geometrical straight lines. Similarly the widespread beliefs of contemporary psychologists cannot rule out the possibility that some of the biased behaviours that they report are actually useful.

Next, I selectively considering the book’s contents in order:

XI Attention

The Intimate Nature of the Attentive Process

[The] only things which we commonly see are those which we preperceive.


Helmholtz has formulated a general law of inattention which we shall have to study in the next chapter but one. Helmholtz s law is that we leave all impressions unnoticed which are valueless to us as signs by which to discriminate things. At most such impressions fuse with their consorts into an aggregate effect.

XII Conception


[This] translation (of perceptions into conceptions) always takes place for the sake of some subjective interest, and how the conception with which we handle a bit of sensible experience is really nothing but a teleological instrument. This whole function of conceiving, of fixing, and holding fast to meanings, has no significance apart from the fact that the conceiver is a creature with partial purposes and private ends.

XIII Discrimination and Comparison

[Any] number of impressions, from any number of sensory sources, falling simultaneously on a mind WHICH HAS NOT YET EXPERIENCED THEM SEPARATELY, will fuse into a single undivided object for that mind. The law is that all things fuse that can fuse, and nothing separates except what must.

 The Process of Analysis

Only such elements as we are acquainted with, and can imagine, separately, can be discriminated within a total sense-impression.

The Process of Abstraction

What is associated now with one thing and now with another tends to become dissociated from either, and to group into an object of abstract contemplation by the mind.

Practical Interests Limit Discrimination

Where, on the other hand, a distinction has no practical interest, where we gain nothing by analyzing a feature from out of the compound total of which it forms a part, we contract a habit of leaving it unnoticed, and at last grow callous to its presence.

 XIV Association

[That] long indulgence in error makes right thinking  almost impossible seems to have no essential foundation in reason.

The Law of Contiguity

[Objects] once experienced together tend to become associated in the imagination, so that when any one of them is thought of, the others are likely to be thought of also, in the same order of sequence or coexistence as before.

The Elementary Law of Association

When two elementary brain-processes have been active together or in immediate succession, one of them, on reoccurring, tends to propagate its excitement into the other.

XIX The Perception of “Things”

Perception Is of Definite and Probable Things

[The] faintest sensations will give rise to the perception of definite things if only they resemble those which the things are wont to arouse. In fact, a sensation must be strong and distinct in order not to suggest an object and, if it is a non-descript feeling, really to seem one.


[These] illusions … are due to two main causes. The wrong object is perceived either because
1) Although not on this occasion the real cause, it is yet the habitual, inveterate, or most probable cause of this ; or because
2) The mind is temporarily full of the thought of that object, and therefore this is peculiarly prone to suggest it at this moment.

XXI The Perception of Reality


What characterizes both consent and belief is the cessation of theoretic agitation, through the advent of an idea which is inwardly stable, and fills the mind solidly to the exclusion of contradictory ideas. …

This inward stability of the mind’s content is as characteristic of disbelief as of belief. But we shall presently see that we never disbelieve anything except for the reason that we believe something else which contradicts the first thing.   The true opposites of belief, psychologically considered, are doubt and inquiry, not disbelief.

The Various Orders of Reality

Any object which remains uncontradicted is ipso facto believed and posited as absolute reality.

[All] propositions, whether attributive or existential, are believed through the very fact of being conceived, unless they clash with other propositions believed, at the same time, by affirming that their terms are the same with the, terms of these other propositions.

The World of “Practical Realities”

The mere fact of appearing as an object at all is not enough to constitute reality. That may be metaphysical reality …; but what we need is practical reality, reality for ourselves ; and, to have that, an object must not only appear, but it must appear both interesting and important. The worlds whose objects are neither interesting nor important we treat simply negatively, we brand them as unreal.

The Paramount Reality of Sensations

Any relation to our mind at all, in the absence of a stronger relation, suffices to make an object real.

Belief in Objects of Theory

The conceived system, to pass for true, must at least include the reality of the sensible objects in it, by explaining them as effects on us, if nothing more. The system which includes the most of them, and definitely explains or pretends to explain the most of them, will, ceteris paribus, prevail. It is needless to say how far mankind still is from having excogitated such a system. But the various materialisms, idealisms, and hylozoisms [hylozoism is the doctrine that all matter has life] show with what industry the attempt is forever made. It is conceivable that several rival theories should equally well include the actual order of our sensations in their scheme, much as the one-fluid and two-fluid theories of electricity formulated all the common electrical phenomena equally well. The sciences are full of these alternatives. Which theory is then to be believed? That theory will be most generally believed which, besides offering us objects able to account satisfactorily for our sensible experience, also offers those which are most interesting, those which appeal most urgently to our aesthetic, emotional, and active needs. So here, in the higher intellectual life, the same selection among general conceptions goes on which went on among the sensations themselves.

It is far too little recognized how entirely the intellect is built up of practical interests.


…  The having and the crediting of an idea do not always coalesce ; for often we first suppose and then believe ; first play with the notion, frame the hypothesis, and then affirm the existence, of an object of thought. And we are quite conscious of the succession of the two mental acts. But these cases are none of them primitive cases. They only occur in minds long schooled to doubt by the contradictions of experience. The primitive impulse is to affirm immediately the reality of all that is conceived.

Relations of Belief and Will

[We] need only in cold blood ACT as if the thing in question were real, and keep acting as if it were real, and it will infallibly end by growing into such a connection with our life that it will become real. It will become so knit with habit and emotion that our interests in it will be those which characterize belief.

My Comments

Logically, we can absolutely know nothing about reality, yet we do form ‘beliefs’, such as that geometrical lines exist in reality. According to James these beliefs should not be regarded as absolute, but depend on various grounds. It thus seems natural to seek to compare the ‘belief-worthiness’ of beliefs. Some versions of probability theory suppose that such comparisons necessarily give a total order, so that there is always – at least in principle a numeric probability or ‘degree of belief’. But from James we get no sense of a total order, merely a partial one.

A belief is, it seems, interesting and important. But it is also a view not worth questioning. If one is in a social setting where questioning is dangerous, then one may be constrained to act as if one believes in the socially constructed dogma. And if one acts as if one believes, one comes to believe: one ‘internalizes’ it.

The quotes from James above suggest  to me a way of comparing ‘belief-worthiness’. In probability theory the more evidence one has for something, the greater its probability. This means that more contrary evidence would be required to make it overall a significant error. And, typically, even if the belief is false then the chances of obtaining contrary evidence any time soon might be slight. For example,  suppose that we have tossed a coin very many times and believe it to be fair, based on our observations. Whatever the next few coin tosses, we will still regard the coin as approximately fair.

Similarly, if one believes that something is not worth questioning, it is often for a reason, which is presumably not worth questioning, and so on in a chain. As for Boole, we may regard each link as weakening the chain, even if we cannot measure the effect. Both the above ways of comparing are consistent with James.

If, years ago, I had gone around studying swans then the probability ‘for me’ that ‘all swans are white’ might well have increased to the point where I simply believed it. But as Captain Cook set sail it may nonetheless occurred to me to doubt it, illustrating another dimension to ‘degrees of belief’ from straightforward probability. What James is suggesting is that our beliefs about reality always involve some belief linking our concepts to reality, for which we have weak grounds.

XXII Reasoning

The Help Given by Association by Similarity

[Our] chief help towards noticing those special characters of phenomena, which, when once possessed and named, are used as reasons, class names, essences, or middle terms, is this association by similarity. Without it, indeed, the deliberate procedure of the scientific man would be impossible: he could never collect his analogous instances. But it operates of itself in highly gifted minds without any deliberation, spontaneously collecting analogous instances, uniting in a moment what in nature the whole breadth of space and time keeps separate, and so permitting a perception of identical points in the midst of different circumstances, which minds governed wholly by the law of contiguity could never begin to attain.


Compared with men, it is probable that brutes neither attend to abstract characters, nor have associations by similarity. Their thoughts probably pass from one concrete object to its habitual concrete successor far more uniformly than is the case with us. In other words, their associations of ideas are almost exclusively by contiguity.

The Intellectual Contrast Between Brute and Man

We may …, consider it proven that the most elementary single difference between the human mind and that of brutes lies in this deficiency on the brute s part to associate ideas by similarity.

Different Orders of Human Genius

The very lack of preappointed trains of thought is the ground on which general principles and heads of classification grow up; and the [genius’] brain deals with new and complex matter indirectly by means of these.

As the art of reading (after a certain stage in one s education) is the art of skipping, so the art of being wise is the art of knowing what to overlook.

When two minds of a high order, interested in kindred subjects, come together, their conversation is chiefly remarkable for the summariness of its allusions and the rapidity of its transitions. Before one of them is half through a sentence the other knows his meaning and replies. Such genial play with such massive materials, such an easy flashing of light over far perspectives, such careless indifference to the dust and apparatus that ordinarily surround the subject and seem to pertain to its essence, make these conversations seem true feasts for gods to a listener who is educated enough to follow them at all. His mental lungs breathe more deeply, in an atmosphere more broad and vast than is their wont. On the other hand, the excessive explicitness and short-windedness of an ordinary man are as wonderful as they are tedious to the man of genius. But we need not go as far as the ways of genius. Ordinary social intercourse will do. There the charm of conversation is in direct proportion to the possibility of abridgment and elision, and in inverse ratio to the need of explicit statement. With old friends a word stands for a whole story or set of opinions. With new-comers everything must be gone over in detail. Some persons have a real mania for completeness, they must express every step. They are the most intolerable of companions, and although their mental energy may in its way be great, they always strike us as weak and second-rate. In short, the essence of plebeianism, that which separates vulgarity from aristocracy, is perhaps less a defect than an excess, the constant need to animadvert upon matters which for the aristocratic temperament do not exist. To ignore, to disdain to consider, to overlook, are the essence of the gentleman. Often most provokingly so; for the things ignored may be of the deepest moral consequence. But in the very midst of our indignation with the gentleman, we have a consciousness that his preposterous inertia and negativeness in the actual emergency is, somehow or other, allied with his general superiority to ourselves. It is not only that the gentleman ignores considerations relative to conduct, sordid suspicions, fears, calculations, etc., which the vulgarian is fated to entertain ; it is that he is silent where the vulgarian talks ; that he gives nothing but results where the vulgarian is profuse of reasons ; that he does not explain or apologize; that he uses one sentence instead of twenty; and that, in a word, there is an amount of interstitial thinking, so to call it, which it is quite impossible to get him to perform, but which is nearly all that the vulgarian mind performs at all. All this suppression of the secondary leaves the field clear, for higher flights, should they choose to come. But even if they never came, what thoughts there were would still manifest the aristocratic type and wear the well-bred form. So great is our sense of harmony and ease in passing from the company of a philistine to that of an aristocratic temperament, that we are almost tempted to deem the falsest views and tastes as held by a man of the world, truer than the truest as held by a common person. In the latter the best ideas are choked, obstructed, and contaminated by the redundancy of their paltry associates. The negative conditions, at least, of an atmosphere and a free outlook are present in the former. … The upshot … simply is that selection implies rejection as well as choice ; and that the function of ignoring, of inattention, is as vital a factor in mental progress as the function of attention itself.

My Comments

Reason, for James, is largely based on classification, which is regarded as instrumental. Yet there seems no way to be sure that any such classification will remain sound. Thus, for me, reliance on a particular classification is something that should challenge belief. James notes that the scientific method relies on classification. It is often noted that some minds and organisations give undue weight to what is measurable. Perhaps they also give undue weight to what is classifiable.

 XXIV Instinct

INSTINCT is usually defined as the faculty of acting in such a way as to produce certain ends, without foresight of the ends, and without previous education in the performance.

Instincts Not Always Blind or Invariable

[No] matter how well endowed, an animal may originally be in the way of instincts, his resultant actions will be much modified if the instincts combine with experience, if in addition to impulses he have memories, associations, inferences, and expectations, on any considerable scale.

Two Principles of Non-uniformity in Instincts

When objects of a certain class elicit from an animal a certain sort of reaction, it often happens that the animal becomes partial to the first specimen of the class on which it has reacted, and will not afterward react on any other specimen.

[Most] instincts are implanted for the sake of giving rise to habits, and that, this purpose once accomplished, the instincts themselves, as such, have no raison d’etre in the psychical economy, and consequently fade away.


A supply of ideas of the various movements that are possible, left in the memory by experiences of their involuntary performance is …  the first prerequisite of the voluntary life.

Action After Deliberation

[Action] and decision are, as such, agreeable, and relieve the tension of doubt and hesitancy. Thus it comes that we will often take any course whatever which happens to be most vividly before our minds, at the moment when this impulse to decisive action becomes extreme.  Against this impulse we have the dread of the irrevocable, which often engenders a type of character incapable of prompt and vigorous resolve, except perhaps when surprised into sudden activity. These two opposing motives twine round whatever other motives may be present at the moment when decision is imminent, and tend to precipitate or retard it. The conflict of these motives so far as they alone affect the matter of decision is a conflict as to when it shall occur. One says now, the other says not yet.  Another constant component of the web of motivation is the impulse to persist in a decision once made. There is no more remarkable difference in human character than that between resolute and irresolute natures. …  Its symptom is that whereas in the irresolute all decisions are provisional and liable to be reversed, in the resolute they are settled once for all and not disturbed again. Now into every one’s deliberations the representation of one alternative will often enter with such sudden force as to carry the imagination with itself exclusively, and to produce an apparently settled decision in its own favor. These premature and spurious decisions are of course known to everyone. They often seem ridiculous in the light of the considerations that succeed them. But it cannot be denied that in the resolute type of character the accident that one of them has once been made does afterwards enter as a motive additional to the more genuine reasons why it should not be revoked, or if provisionally revoked, why it should be made again. How many of us persist in a precipitate course which, but for a moment of heedlessness, we might never have entered upon, simply because we hate to change our mind.

Five Types of Decision

Turning now to the form of the decision itself, we may distinguish four chief types. The first may be called the reasonable type. …  The conclusive reason for the decision in these cases usually is the discovery that we can refer the case to a class upon which we are accustomed to act unhesitatingly in a certain stereo typed way. It may be said in general that a great part of every deliberation consists in the turning over of all the possible modes of conceiving the doing or not doing of the act in point. The moment we hit upon a conception which lets us apply some principle of action which is a fixed and stable part of our Ego, our state of doubt is at an end. Persons of authority, who have to make many decisions in the day, carry with them a set of heads of classification, each bearing its motor consequence, and under these they seek as far as possible to range each new emergency as it occurs. It is where the emergency belongs to a species without precedent, to which consequently no cut-and-dried maxim will apply, that we feel most at a loss, and are distressed at the indeterminateness of our task. As soon, however, as we see our way to a familiar classification, we are at ease again. In action as in reasoning, then, the great thing is the quest of the right conception. The concrete dilemmas do not come to us with labels gummed upon their backs. We may name them by many names. The wise man is he who succeeds in finding the name which suits the needs of the particular occasion best. A reasonable character is one who has a store of stable and worthy ends, and who does not decide about an action till he has calmly ascertained whether it be ministerial or detrimental to any one of these.

In the second type of case our feeling is to a certain extent that of letting ourselves drift with a certain in different acquiescence in a direction accidentally determined from without, with the conviction that, after all, we might as well stand by this course as by the other, and that things are in any event sure to turn out sufficiently right.

XXVIII Necessary …

This was discussed at the start.

My Comments on the above

It seems that scientists and presumably other experts and authorities have a tendency and will, perhaps intuitive, to systematize. That is, they develop theories and conceptual models that they seek to apply directly, with confidence, as if ‘the map ‘is’ the territory’. It follows from James’ work on beliefs that they will tend to believe these theories, and in the over-arching notion that such modelling and their application is credible and sensible. Indeed, they hold it to be ‘rational’ and hence beyond reasonable doubt. Yet the expert’s reasoning will be based on their experience. Without criticising the expert’s application of their professional skills, we might often doubt their findings as they apply to us, because we doubt that their experience is relevant to ours. At this point some experts may claim that their beliefs are ‘universal’ or ‘context-independent’, but we may not find this convincing. It may simply be that they do not doubt their beliefs because they have not had cause to.

The hallmark of a ‘proper science’, then is that it has an established domain within which it has long-established beliefs that have been meaningfully challenged, with all ‘degrees of belief’ tested, justifying a high degree of belief in all dimensions.

My Overall Comments

All of the above suggest to me that in the short-term we match what we sense to our mental constructs, and in the longer term we may update our constructs, but only when we admit to some need, which we will be loth to do if the sense-making habit is well established. In particular, there seems to be some psychological law of induction: the longer something has been established without any apparent snags, the firmer it is established and the less likely to be revised.

There is also an issue of discrimination. If we fail to make a particular discrimination then we may wrangle with reality as much as we will and yet find no reason to doubt our beliefs, perhaps attributing variability and unpredictability to randomness. Thus in challenging the views of others (including ‘experts’) we should look for discriminations and factors that they may have overlooked.

Dave Marsay


%d bloggers like this: