An Enquiry Concerning Human Understanding

119. So far, then, are we necessitated by reasoning to contradict or depart from the primary instincts of nature, and to embrace a new system with regard to the evidence of our senses. But here philosophy finds herself extremely embarrassed, when she would justify this new system, and obviate the cavils and objections of the sceptics. She can no longer plead the infallible and irresistible instinct of nature: for that led us to a quite different system, which is acknowledged fallible and even erroneous. And to justify this pretended philosophical system, by a chain of clear and convincing argument, or even any appearance of argument, exceeds the power of all human capacity.

By what argument can it be proved, that the perceptions of the mind must be caused by external objects, entirely different from them, though resembling them (if that be possible) and could not arise either from the energy of the mind itself, or from the suggestion of some invisible and unknown spirit, or from some other cause still more unknown to us? It is acknowledged, that, in fact, many of these perceptions arise not from anything external, as in dreams, madness, and other diseases. And nothing can be more inexplicable than the manner, in which body should so operate upon mind as ever to convey an image of itself to a substance, supposed of so different, and even contrary a nature.

It is a question of fact, whether the perceptions of the senses be produced by external objects, resembling them: how shall this question be determined? By experience surely; as all other questions of a like nature. But here experience is, and must be entirely silent. The mind has never anything present to it but the perceptions, and cannot possibly reach any experience of their connexion with objects. The supposition of such a connexion is, therefore, without any foundation in reasoning.

120. To have recourse to the veracity of the supreme Being, in order to prove the veracity of our senses, is surely making a very unexpected circuit. If his veracity were at all concerned in this matter, our senses would be entirely infallible; because it is not possible that he can ever deceive. Not to mention, that, if the external world be once called in question, we shall be at a loss to find arguments, by which we may prove the existence of that Being or any of his attributes.

121. This is a topic, therefore, in which the profounder and more philosophical sceptics will always triumph, when they endeavour to introduce an universal doubt into all subjects of human knowledge and enquiry. Do you follow the instincts and propensities of nature, may they say, in assenting to the veracity of sense? But these lead you to believe that the very perception or sensible image is the external object. Do you disclaim this principle, in order to embrace a more rational opinion, that the perceptions are only representations of something external? You here depart from your natural propensities and more obvious sentiments; and yet are not able to satisfy your reason, which can never find any convincing argument from experience to prove, that the perceptions are connected with any external objects.

122. There is another sceptical topic of a like nature, derived from the most profound philosophy; which might merit our attention, were it requisite to dive so deep, in order to discover arguments and reasonings, which can so little serve to any serious purpose. It is universally allowed by modern enquirers, that all the sensible qualities of objects, such as hard, soft, hot, cold, white, black, &c. are merely secondary, and exist not in the objects themselves, but are perceptions of the mind, without any external archetype or model, which they represent. If this be allowed, with regard to secondary qualities, it must also follow, with regard to the supposed primary qualities of extension and solidity; nor can the latter be any more entitled to that denomination than the former. The idea of extension is entirely acquired from the senses of sight and feeling; and if all the qualities, perceived by the senses, be in the mind, not in the object, the same conclusion must reach the idea of extension, which is wholly dependent on the sensible ideas or the ideas of secondary qualities. Nothing can save us from this conclusion, but the asserting, that the ideas of those primary qualities are attained by _Abstraction_, an opinion, which, if we examine it accurately, we shall find to be unintelligible, and even absurd. An extension, that is neither tangible nor visible, cannot possibly be conceived: and a tangible or visible extension, which is neither hard nor soft, black nor white, is equally beyond the reach of human conception. Let any man try to conceive a triangle in general, which is neither _Isosceles_ nor _Scalenum_, nor has any particular length or proportion of sides; and he will soon perceive the absurdity of all the scholastic notions with regard to abstraction and general ideas.[31]

[31] This argument is drawn from Dr. Berkeley; and indeed most of the writings of that very ingenious author form the best lessons of scepticism, which are to be found either among the ancient or modern philosopher, Bayle not excepted. He professes, however, in his title-page (and undoubtedly with great truth) to have composed his book against the sceptics as well as against the atheists and free-thinkers. But that all his arguments, though otherwise intended, are, in reality, merely sceptical, appears from this, _that they admit of no answer and produce no conviction_. Their only effect is to cause that momentary amazement and irresolution and confusion, which is the result of scepticism.

123. Thus the first philosophical objection to the evidence of sense or to the opinion of external existence consists in this, that such an opinion, if rested on natural instinct, is contrary to reason, and if referred to reason, is contrary to natural instinct, and at the same time carries no rational evidence with it, to convince an impartial enquirer. The second objection goes farther, and represents this opinion as contrary to reason: at least, if it be a principle of reason, that all sensible qualities are in the mind, not in the object. Bereave matter of all its intelligible qualities, both primary and secondary, you in a manner annihilate it, and leave only a certain unknown, inexplicable _something_, as the cause of our perceptions; a notion so imperfect, that no sceptic will think it worth while to contend against it.

124. It may seem a very extravagant attempt of the sceptics to destroy _reason_ by argument and ratiocination; yet is this the grand scope of all their enquiries and disputes. They endeavour to find objections, both to our abstract reasonings, and to those which regard matter of fact and existence.

The chief objection against all _abstract_ reasonings is derived from the ideas of space and time; ideas, which, in common life and to a careless view, are very clear and intelligible, but when they pass through the scrutiny of the profound sciences (and they are the chief object of these sciences) afford principles, which seem full of absurdity and contradiction. No priestly _dogmas_, invented on purpose to tame and subdue the rebellious reason of mankind, ever shocked common sense more than the doctrine of the infinitive divisibility of extension, with its consequences; as they are pompously displayed by all geometricians and metaphysicians, with a kind of triumph and exultation. A real quantity, infinitely less than any finite quantity, containing quantities infinitely less than itself, and so on _in infinitum_; this is an edifice so bold and prodigious, that it is too weighty for any pretended demonstration to support, because it shocks the clearest and most natural principles of human reason.[32] But what renders the matter more extraordinary, is, that these seemingly absurd opinions are supported by a chain of reasoning, the clearest and most natural; nor is it possible for us to allow the premises without admitting the consequences. Nothing can be more convincing and satisfactory than all the conclusions concerning the properties of circles and triangles; and yet, when these are once received, how can we deny, that the angle of contact between a circle and its tangent is infinitely less than any rectilineal angle, that as you may increase the diameter of the circle _in infinitum_, this angle of contact becomes still less, even _in infinitum_, and that the angle of contact between other curves and their tangents may be infinitely less than those between any circle and its tangent, and so on, _in infinitum_? The demonstration of these principles seems as unexceptionable as that which proves the three angles of a triangle to be equal to two right ones, though the latter opinion be natural and easy, and the former big with contradiction and absurdity. Reason here seems to be thrown into a kind of amazement and suspence, which, without the suggestions of any sceptic, gives her a diffidence of herself, and of the ground on which she treads. She sees a full light, which illuminates certain places; but that light borders upon the most profound darkness. And between these she is so dazzled and confounded, that she scarcely can pronounce with certainty and assurance concerning any one object.

[32] Whatever disputes there may be about mathematical points, we must allow that there are physical points; that is, parts of extension, which cannot be divided or lessened, either by the eye or imagination. These images, then, which are present to the fancy or senses, are absolutely indivisible, and consequently must be allowed by mathematicians to be infinitely less than any real part of extension; and yet nothing appears more certain to reason, than that an infinite number of them composes an infinite extension. How much more an infinite number of those infinitely small parts of extension, which are still supposed infinitely divisible.

125. The absurdity of these bold determinations of the abstract sciences seems to become, if possible, still more palpable with regard to time than extension. An infinite number of real parts of time, passing in succession, and exhausted one after another, appears so evident a contradiction, that no man, one should think, whose judgement is not corrupted, instead of being improved, by the sciences, would ever be able to admit of it.

Yet still reason must remain restless, and unquiet, even with regard to that scepticism, to which she is driven by these seeming absurdities and contradictions. How any clear, distinct idea can contain circumstances, contradictory to itself, or to any other clear, distinct idea, is absolutely incomprehensible; and is, perhaps, as absurd as any proposition, which can be formed. So that nothing can be more sceptical, or more full of doubt and hesitation, than this scepticism itself, which arises from some of the paradoxical conclusions of geometry or the science of quantity.[33]

[33] It seems to me not impossible to avoid these absurdities and contradictions, if it be admitted, that there is no such thing as abstract or general ideas, properly speaking; but that all general ideas are, in reality, particular ones, attached to a general term, which recalls, upon occasion, other particular ones, that resemble, in certain circumstances, the idea, present to the mind. Thus when the term Horse is pronounced, we immediately figure to ourselves the idea of a black or a white animal, of a particular size or figure: But as that term is also usually applied to animals of other colours, figures and sizes, these ideas, though not actually present to the imagination, are easily recalled; and our reasoning and conclusion proceed in the same way, as if they were actually present. If this be admitted (as seems reasonable) it follows that all the ideas of quantity, upon which mathematicians reason, are nothing but particular, and such as are suggested by the senses and imagination, and consequently, cannot be infinitely divisible. It is sufficient to have dropped this hint at present, without prosecuting it any farther. It certainly concerns all lovers of science not to expose themselves to the ridicule and contempt of the ignorant by their conclusions; and this seems the readiest solution of these difficulties.

126. The sceptical objections to _moral_ evidence, or to the reasonings concerning matter of fact, are either _popular_ or _philosophical_. The popular objections are derived from the natural weakness of human understanding; the contradictory opinions, which have been entertained in different ages and nations; the variations of our judgement in sickness and health, youth and old age, prosperity and adversity; the perpetual contradiction of each particular man's opinions and sentiments; with many other topics of that kind. It is needless to insist farther on this head. These objections are but weak. For as, in common life, we reason every moment concerning fact and existence, and cannot possibly subsist, without continually employing this species of argument, any popular objections, derived from thence, must be insufficient to destroy that evidence. The great subverter of _Pyrrhonism_ or the excessive principles of scepticism is action, and employment, and the occupations of common life. These principles may flourish and triumph in the schools; where it is, indeed, difficult, if not impossible, to refute them. But as soon as they leave the shade, and by the presence of the real objects, which actuate our passions and sentiments, are put in opposition to the more powerful principles of our nature, they vanish like smoke, and leave the most determined sceptic in the same condition as other mortals.

127. The sceptic, therefore, had better keep within his proper sphere, and display those _philosophical_ objections, which arise from more profound researches. Here he seems to have ample matter of triumph; while he justly insists, that all our evidence for any matter of fact, which lies beyond the testimony of sense or memory, is derived entirely from the relation of cause and effect; that we have no other idea of this relation than that of two objects, which have been frequently _conjoined_ together; that we have no argument to convince us, that objects, which have, in our experience, been frequently conjoined, will likewise, in other instances, be conjoined in the same manner; and that nothing leads us to this inference but custom or a certain instinct of our nature; which it is indeed difficult to resist, but which, like other instincts, may be fallacious and deceitful. While the sceptic insists upon these topics, he shows his force, or rather, indeed, his own and our weakness; and seems, for the time at least, to destroy all assurance and conviction. These arguments might be displayed at greater length, if any durable good or benefit to society could ever be expected to result from them.

128. For here is the chief and most confounding objection to _excessive_ scepticism, that no durable good can ever result from it; while it remains in its full force and vigour. We need only ask such a sceptic, _What his meaning is? And what he proposes by all these curious researches?_ He is immediately at a loss, and knows not what to answer. A Copernican or Ptolemaic, who supports each his different system of astronomy, may hope to produce a conviction, which will remain constant and durable, with his audience. A Stoic or Epicurean displays principles, which may not be durable, but which have an effect on conduct and behaviour. But a Pyrrhonian cannot expect, that his philosophy will have any constant influence on the mind: or if it had, that its influence would be beneficial to society. On the contrary, he must acknowledge, if he will acknowledge anything, that all human life must perish, were his principles universally and steadily to prevail. All discourse, all action would immediately cease; and men remain in a total lethargy, till the necessities of nature, unsatisfied, put an end to their miserable existence. It is true; so fatal an event is very little to be dreaded. Nature is always too strong for principle. And though a Pyrrhonian may throw himself or others into a momentary amazement and confusion by his profound reasonings; the first and most trivial event in life will put to flight all his doubts and scruples, and leave him the same, in every point of action and speculation, with the philosophers of every other sect, or with those who never concerned themselves in any philosophical researches. When he awakes from his dream, he will be the first to join in the laugh against himself, and to confess, that all his objections are mere amusement, and can have no other tendency than to show the whimsical condition of mankind, who must act and reason and believe; though they are not able, by their most diligent enquiry, to satisfy themselves concerning the foundation of these operations, or to remove the objections, which may be raised against them.

129. There is, indeed, a more _mitigated_ scepticism or _academical_ philosophy, which may be both durable and useful, and which may, in part, be the result of this Pyrrhonism, or _excessive_ scepticism, when its undistinguished doubts are, in some measure, corrected by common sense and reflection. The greater part of mankind are naturally apt to be affirmative and dogmatical in their opinions; and while they see objects only on one side, and have no idea of any counterpoising argument, they throw themselves precipitately into the principles, to which they are inclined; nor have they any indulgence for those who entertain opposite sentiments. To hesitate or balance perplexes their understanding, checks their passion, and suspends their action. They are, therefore, impatient till they escape from a state, which to them is so uneasy: and they think, that they could never remove themselves far enough from it, by the violence of their affirmations and obstinacy of their belief. But could such dogmatical reasoners become sensible of the strange infirmities of human understanding, even in its most perfect state, and when most accurate and cautious in its determinations; such a reflection would naturally inspire them with more modesty and reserve, and diminish their fond opinion of themselves, and their prejudice against antagonists. The illiterate may reflect on the disposition of the learned, who, amidst all the advantages of study and reflection, are commonly still diffident in their determinations: and if any of the learned be inclined, from their natural temper, to haughtiness and obstinacy, a small tincture of Pyrrhonism might abate their pride, by showing them, that the few advantages, which they may have attained over their fellows, are but inconsiderable, if compared with the universal perplexity and confusion, which is inherent in human nature. In general, there is a degree of doubt, and caution, and modesty, which, in all kinds of scrutiny and decision, ought for ever to accompany a just reasoner.

130. Another species of _mitigated_ scepticism which may be of advantage to mankind, and which may be the natural result of the Pyrrhonian doubts and scruples, is the limitation of our enquiries to such subjects as are best adapted to the narrow capacity of human understanding. The _imagination_ of man is naturally sublime, delighted with whatever is remote and extraordinary, and running, without control, into the most distant parts of space and time in order to avoid the objects, which custom has rendered too familiar to it. A correct _Judgement_ observes a contrary method, and avoiding all distant and high enquiries, confines itself to common life, and to such subjects as fall under daily practice and experience; leaving the more sublime topics to the embellishment of poets and orators, or to the arts of priests and politicians. To bring us to so salutary a determination, nothing can be more serviceable, than to be once thoroughly convinced of the force of the Pyrrhonian doubt, and of the impossibility, that anything, but the strong power of natural instinct, could free us from it. Those who have a propensity to philosophy, will still continue their researches; because they reflect, that, besides the immediate pleasure, attending such an occupation, philosophical decisions are nothing but the reflections of common life, methodized and corrected. But they will never be tempted to go beyond common life, so long as they consider the imperfection of those faculties which they employ, their narrow reach, and their inaccurate operations. While we cannot give a satisfactory reason, why we believe, after a thousand experiments, that a stone will fall, or fire burn; can we ever satisfy ourselves concerning any determination, which we may form, with regard to the origin of worlds, and the situation of nature, from, and to eternity?

This narrow limitation, indeed, of our enquiries, is, in every respect, so reasonable, that it suffices to make the slightest examination into the natural powers of the human mind and to compare them with their objects, in order to recommend it to us. We shall then find what are the proper subjects of science and enquiry.

131. It seems to me, that the only objects of the abstract science or of demonstration are quantity and number, and that all attempts to extend this more perfect species of knowledge beyond these bounds are mere sophistry and illusion. As the component parts of quantity and number are entirely similar, their relations become intricate and involved; and nothing can be more curious, as well as useful, than to trace, by a variety of mediums, their equality or inequality, through their different appearances. But as all other ideas are clearly distinct and different from each other, we can never advance farther, by our utmost scrutiny, than to observe this diversity, and, by an obvious reflection, pronounce one thing not to be another. Or if there be any difficulty in these decisions, it proceeds entirely from the undeterminate meaning of words, which is corrected by juster definitions. That _the square of the hypothenuse is equal to the squares of the other two sides_, cannot be known, let the terms be ever so exactly defined, without a train of reasoning and enquiry. But to convince us of this proposition, _that where there is no property, there can be no injustice_, it is only necessary to define the terms, and explain injustice to be a violation of property. This proposition is, indeed, nothing but a more imperfect definition. It is the same case with all those pretended syllogistical reasonings, which may be found in every other branch of learning, except the sciences of quantity and number; and these may safely, I think, be pronounced the only proper objects of knowledge and demonstration.

132. All other enquiries of men regard only matter of fact and existence; and these are evidently incapable of demonstration. Whatever _is_ may _not be_. No negation of a fact can involve a contradiction. The non-existence of any being, without exception, is as clear and distinct an idea as its existence. The proposition, which affirms it not to be, however false, is no less conceivable and intelligible, than that which affirms it to be. The case is different with the sciences, properly so called. Every proposition, which is not true, is there confused and unintelligible. That the cube root of 64 is equal to the half of 10, is a false proposition, and can never be distinctly conceived. But that Caesar, or the angel Gabriel, or any being never existed, may be a false proposition, but still is perfectly conceivable, and implies no contradiction.

The existence, therefore, of any being can only be proved by arguments from its cause or its effect; and these arguments are founded entirely on experience. If we reason _a priori_, anything may appear able to produce anything. The falling of a pebble may, for aught we know, extinguish the sun; or the wish of a man control the planets in their orbits. It is only experience, which teaches us the nature and bounds of cause and effect, and enables us to infer the existence of one object from that of another[34]. Such is the foundation of moral reasoning, which forms the greater part of human knowledge, and is the source of all human action and behaviour.

[34] That impious maxim of the ancient philosophy, _Ex nihilo, nihil fit_, by which the creation of matter was excluded, ceases to be a maxim, according to this philosophy. Not only the will of the supreme Being may create matter; but, for aught we know _a priori_, the will of any other being might create it, or any other cause, that the most whimsical imagination can assign.

Moral reasonings are either concerning particular or general facts. All deliberations in life regard the former; as also all disquisitions in history, chronology, geography, and astronomy.

The sciences, which treat of general facts, are politics, natural philosophy, physic, chemistry, &c. where the qualities, causes and effects of a whole species of objects are enquired into.

Divinity or Theology, as it proves the existence of a Deity, and the immortality of souls, is composed partly of reasonings concerning particular, partly concerning general facts. It has a foundation in _reason_, so far as it is supported by experience. But its best and most solid foundation is _faith_ and divine revelation.

Morals and criticism are not so properly objects of the understanding as of taste and sentiment. Beauty, whether moral or natural, is felt, more properly than perceived. Or if we reason concerning it, and endeavour to fix its standard, we regard a new fact, to wit, the general tastes of mankind, or some such fact, which may be the object of reasoning and enquiry.

When we run over libraries, persuaded of these principles, what havoc must we make? If we take in our hand any volume; of divinity or school metaphysics, for instance; let us ask, _Does it contain any abstract reasoning concerning quantity or number?_ No. _Does it contain any experimental reasoning concerning matter of fact and existence?_ No. Commit it then to the flames: for it can contain nothing but sophistry and illusion.

Abstraction not source of ideas of primary qualities, 122.

Analogy a species of, the foundation of all reasoning about matter of fact, 82;

Animals the reason of, 83-85; learn from experience and draw inferences, 83; which can only be founded on custom, 84; cause of difference between men and animals, 84 n.

Appearances to senses must be corrected by reason, 117.

Association of ideas, three principles of, 18-19, 41-44 (v. _Cause_ C).

Belief (v. _Cause_ C, 39-45); and chance, 46.

Body and soul, mystery of union of, 52; volition and movements of, 52.

Real existence of (v. _Scepticism_, B, 118-123).

Cause first (v. _God_, _Necessity_, 78-81; _Providence_, 102-115, 132 n). a principle of association of ideas, 19, 43; sole foundation of reasonings about matter of fact or real existence, 22.

A. _Knowledge of Causes arises from experience not from Reason_, 23-33.

Reasonings _a priori_ give no knowledge of cause and effect, 23 f.; impossible to see the effect in the cause since they are totally different, 25; natural philosophy never pretends to assign ultimate causes, but only to reduce causes to a few general causes, e.g. gravity, 26; geometry applies laws obtained by experience, 27.

Conclusions from experience not based on any process of the understanding, 28; yet we infer in the future a similar connexion between known qualities of things and their secret powers, to that which we assumed in the past. On what is this inference based? 29; demonstrative reasoning has no place here, and all experimental reasoning assumes the resemblance of the future to the past, and so cannot prove it without being circular, 30, 32; if reasoning were the basis of this belief, there would be no need for the multiplication of instances or of long experience, 31; yet conclusions about matter of fact are affected by experience even in beasts and children, so that they cannot be founded on abstruse reasoning, 33; to explain our inferences from experience a principle is required of equal weight and authority with reason, 34.

B. _Custom enables us to infer existence of one object from the appearance of another_, 35-38.

Experience enables us to ascribe a more than arbitrary connexion to objects, 35; we are determined to this by custom or habit which is the great guide of human life, 36; but our inference must be based on some fact present to the senses or memory, 37; the customary conjunction between such an object and some other object produces an operation of the soul which is as unavoidable as love, 38; animals also infer one event from another by custom, 82-84; and in man as in animals experimental reasoning depends on a species of instinct or mechanical power that acts in us unknown to ourselves, 85.

C. _Belief_, 39-45. Belief differs from fiction or the loose reveries of the fancy by some feeling annexed to it, 39; belief cannot be defined, but may be described as a more lively, forcible, firm, steady conception of an object than can be attained by the imagination alone, 40; it is produced by the principles of association, viz. resemblance, 41; contiguity, 42; causation, 43; by a kind of pre-established harmony between the course of nature and our ideas, 44; this operation of our minds necessary to our subsistence and so entrusted by nature to instinct rather than to reasoning, 45.

Belief produced by a majority of chances by an inexplicable contrivance of Nature, 46 (cf. 87-8); probability of causes: the failure of a cause ascribed to a secret counteracting cause, 47 (cf. 67); it is universally allowed that chance when strictly examined is a mere negative word, 74.

Power, force, energy, necessary connexion must either be defined by analysis or explained by production of the impression from which they are copied, 49; from the first appearance of an object we cannot foretell its effect: we cannot see the power of a single body: we only see sequence, 50.

Is the idea of power derived from an internal impression and is it an idea of reflection? 51; it is not derived, as Locke said, from reasoning about power of production in nature, 50 n; nor from consciousness of influence of will over bodily organs, 52; nor from effort to overcome resistance, 52 n (cf. 60 n); nor from influence of will over mind, 53; many philosophers appeal to an invisible intelligent principle, to a volition of the supreme being, and regard causes as only occasions and our mental conceptions as revelations, 54-5; thus diminishing the grandeur of God, 56; this theory too bold and beyond verification by our faculties, and is no explanation, 57; vis inertiae, 57 n.

In single instances we only see sequence of loose events which are conjoined and never connected, 58; the idea of necessary connexion only arises from a number of similar instances, and the only difference between such a number and a single instance is that the former produces a habit of expecting the usual attendant, 59, 61. This customary transition is the impression from which we form the idea of necessary connexion.

E. _Reasoning from effect to cause and conversely_, 105-115 (v. _Providence_).

In arguing from effect to cause we must not infer more qualities in the cause than are required to produce the effect, nor reason backwards from an inferred cause to new effects, 105-8; we can reason back from cause to new effects in the case of human acts by analogy which rests on previous knowledge, 111-2; when the effect is entirely singular and does not belong to any species we cannot infer its cause at all, 115.

F. _Definitions of Cause_, 60 (cf. 74 n).

Chance ignorance of causes, 46; has no existence, 74 (v. _Cause_ B).

Contradiction the test of demonstration, 132.

Contrary of matter of fact always possible, 21, 132.

Custom when strongest conceals itself, 24; an ultimate principle of all conclusions from experience, 36, 127; and belief, 39-45; gives rise to inferences of animals, 84.

Definition only applicable to complex ideas, 49; need of, 131; of cause, 60.

Demonstrative opp. intuitive, 20; reasoning, 30; confined to quantity and number, 131; impossible to demonstrate a fact since no negation of a fact can involve a contradiction, 132.

Descartes 57 n.; his universal doubt antecedent to study if strictly taken is incurable, since even from an indubitable first principle no advance can be made except by the faculties which we doubt, 116; his appeal to the veracity of God is useless, 120 (v. _Scepticism_, 116-132).

Design argument from, 105 f. (v. _Providence_).

Divisibility of mathematical and physical points, 124.

Doubt Cartesian, 116, 120 (v. _Scepticism_ A).

Epicurean philosophy, defence of, 102-15; denial of providence and future state is harmless, 104 (v. _Providence_).

Euclid truths in, do not depend on existence of circles or triangles, 20.

Evidence moral and natural, 70; value of human, 82-9 (v. _Miracles_).

Evil doctrine of necessity either makes God the cause of evil or denies existence of evil as regards the whole, 78-81.

Existence external and perception, 118-9 (v. _Scepticism_, B, 116-32).

Experience (v. _Cause_ A, 23-33); opposition of reason and experience usual, but really erroneous and superficial, 36 n.

Infallible, may be regarded as proof, 87 (v. _Miracles_); all the philosophy and religion in the world cannot carry us beyond the usual course of experience, 113.

Extension 50; a supposed primary quality, 122.

Future inference to, from past, 29 (v. _Cause_ A).

General ideas, do not really exist, but only particular ideas attached to a general term, 125 n.

Geometry propositions of certain, as depending only on relations of ideas not on existence of objects, 20; gives no knowledge of ultimate causes: only applies laws discovered by experience, 27.

God idea of, 14; no idea of except what we learn from reflection on our own faculties, 57; theory that God is cause of all motion and thought, causes being only occasions of his volition, 54-57; by doctrine of necessity either there are no bad actions or God is the cause of evil, 78-81.

v. _Providence_, 102-115; _Scepticism_, 116-132.

Human nature, inconstancy a constant character of, 68.

Perceptions divided into impressions and ideas, 11-12; the mind can only compound the materials derived from outward or inward sentiment, 13 (cf. 53); all ideas resolvable into simple ideas copied from precedent feelings, 14; deficiency in an organ of sensation produces deficiency in corresponding idea, 15-16; suspected ideas to be tested by asking for the impression from which it is derived, 17 (cf. 49); idea of reflection, 51; general ideas, 135 n; innate ideas, 19 n; power of will over ideas, 53.

Ideas introduce each other with a certain degree of method and regularity, 18; only three principles of association, viz. Resemblance, Contiguity, and Cause or Effect, 19; contrariety, 19 n; production of belief by these principles, 41-43.

C. Correspondence of ideas and course of nature, 44; relations of ideas one of two possible objects of enquiry, 20; such relations discoverable by the mere operation of thought, 20, 131; no demonstration possible except in case of ideas of quantity or number, 131.

Impressions all our more lively perceptions, 12; the test of ideas, 17, 49.

Incest peculiar turpitude of explained, 12.

Inconceivability of the negative, 132 (cf. 20).

Inference and similarity, 30, 115 (v. _Cause_).

Instances multiplication of not required by reason, 31.

Instinct more trustworthy than reasoning, 45; the basis of all experimental reasoning, 85; the basis of realism, 118, 121.

Liberty (v. _Necessity_, 62-97). Definition of hypothetical liberty, 73. Necessary to morality, 77.

Locke 4, 40 n, 50 n, 57 n. His loose use of 'ideas,' 19 n; betrayed into frivolous disputes about innate ideas by the School-men, 19 n; distinction of primary and secondary qualities, 122.

Marriage rules of, based on and vary with utility, 118.

Mathematics ideas of, clear and determinate, hence their superiority to moral and metaphysical sciences, 48; their difficulty, 48.

Matter necessity of, 64; creation of, 132 n (v. _Scepticism_ A).

Matter-of-fact contrary of, always possible, 21; arguments to new, based only on cause and effect, 22.

Metaphysics not a science, 5-6; how inferior and superior to mathematics, 48.

Mind mental geography, 8; secret springs and principles of, 9; can only mix and compound materials given by inward and outward sentiment, 13; power of will over, 53.

Belief in human evidence diminishes according as the event witnessed is unusual or extraordinary, 89; difference between extraordinary and miraculous, 89 n; if the evidence for a miracle amounted to proof we should have one proof opposed by another proof, for the proof against a miracle is as complete as possible; an event is not miraculous unless there is a uniform experience, that is a proof, against it, 90; definition of miracle, 90 n; hence no testimony is sufficient to establish a miracle unless its falsehood would be more miraculous than the event it establishes, 91; as a fact the evidence for a miracle has never amounted to proof, 92; the passion for the wonderful in human nature, 93; prevalence of miracles in savage and early periods and their diminution with civilization, 94; the evidence for miracles in matters of religion opposed by the almost infinite number of witnesses for rival religions, 95; value of human testimony diminished by temptation to pose as a prophet or apostle, 97; no testimony for a miracle has ever amounted to a probability, much less to a proof, and if it did amount to a proof it would be opposed by another perfect proof, 98; so a miracle can never be proved so as to be the foundation of a system of religion, 99; a conclusion which confounds those who base the Christian religion on reason, not on faith, 100; the Christian religion cannot be believed without a miracle which will subvert the principle of a man's understanding and give him a determination to believe what is most contrary to custom and experience, 101.

Moral science 30; inferior to mathematics, 48; sceptical objections to, 126-7.

Moral evidence easily combined with natural, 70.

Nature design in, 105 f. (v. _Providence_), and the course of our ideas, 44.

State of, a philosophical fiction, 151, 151 n.

A. _and Liberty_, 62-81; the controversy is based on ambiguity, and all mankind have always been of the same opinion on this subject, 63; our idea of the necessity of matter arises solely from observed uniformity and consequent inference, circumstances which are allowed by all men to exist in respect of human action, 64; history and knowledge of human nature assume such uniformity, 65, which does not exclude variety due to education and progress, 66; irregular actions to be explained by secret operation of contrary causes, 67; the inconstancy of human action, its constant character, as of winds and weather, 68; we all acknowledge and draw inferences from the regular conjunction of motives and actions, 69; history, politics, and morals show this, and the possibility of combining moral and natural evidence shows that they have a common origin, 70; the reluctance to acknowledge the necessity of actions due to a lingering belief that we can see real connexion behind mere conjunction, 71; we should begin with the examination not of the soul and will but of brute matter, 72; the prevalence of the liberty doctrine due to a false sensation of liberty and a false experiment, 72 n; though this question is the most contentious of all, mankind has always agreed in the doctrine of liberty, if we mean by it that hypothetical liberty which consists in a power of acting or not acting according to the determinations of our will, and which can be ascribed to every one who is not a prisoner, 73; liberty when opposed to necessity, and not merely to constraint, is the same as chance, 74.

B. _Both necessity and liberty are necessary to morality_, this doctrine of necessity only alters our view of matter and so is at least innocent, 75; rewards and punishments imply the uniform influence of motives, and connexion of character and action: if necessity be denied, a man may commit any crime and be no worse for it, 76; liberty also essential to morality, 77.

Objection that doctrine of necessity and of a regular chain of causes either makes God the cause of evil, or abolishes evil in actions, 78; Stoic answer, that the whole system is good, is specious but ineffectual in practice, 79; no speculative argument can counteract the impulse of our natural sentiments to blame certain actions, 80; how God can be the cause of all actions without being the author of moral evil is a mystery with which philosophy cannot deal, 81.

Parallelism between thought and course of nature, 44-5.

Perception and external objects, 119 f. (v. _Scepticism_, _Impression_, _Idea_).

Philosophy moral, two branches of, abstruse and practical, 1-5; gratifies innocent curiosity, 6; metaphysics tries to deal with matters inaccessible to human understanding, 6.

True, must lay down limits of understanding, 7 (cf. 113); a large part of, consists in mental geography, 8; may hope to resolve principles of mind into still more general principles, 9.

Natural, only staves off our ignorance a little longer, as moral or metaphysical philosophy serves only to discover larger portions of it, 26; academical, or sceptical, flatters no bias or passion except love of truth, and so has few partisans, 34; though it destroy speculation, cannot destroy action, for nature steps in and asserts her rights, 34; moral, inferior to mathematics in clearness of ideas, superior in shortness of arguments, 48.

Controversies in, due to ambiguity of terms, 62.

Disputes in, not be settled by appeal to dangerous consequences of a doctrine, 75.

Speculative, entirely indifferent to the peace of society and security of government, 104 (cf. 114).

All the philosophy in the world, and all the religion in the world, which is nothing but a species of philosophy, can never carry us beyond the usual course of experience, 113.

Happiness of, to have originated in an age and country of freedom and toleration, 102.

Promises not the foundation of justice, 257.

Proof 46 n, 86-101 (v. _Miracles_, _Demonstrative_).

The sole argument for a divine existence is from the marks of design in nature; must not infer greater power in the cause than is necessary to produce the observed effects, nor argue from such an inferred cause to any new effects which have not been observed, 105; so must not infer in God more power, wisdom, and benevolence than appears in nature, 106; so it is unnecessary to try and save the honour of the Gods by assuming the intractability of matter or the observance of general laws, 107; to argue from effects to unknown causes, and then from these causes to unknown effects, is a gross sophism, 108.

From imperfect exercise of justice in this world we cannot infer its perfect exercise in a future world, 109; we must regulate our conduct solely by the experienced train of events, 110; in case of human works of art we can infer the perfect from the imperfect, but that is because we know man by experience and also know other instances of his art, 111-112; but in the case of God we only know him by his productions, and do not know any class of beings to which he belongs, 113; and the universe, his production, is entirely singular and does not belong to a known species of things, 115.

Punishment requires doctrines of necessity and liberty, 76 (v. _Necessity_).

Quantity and number, the only objects of demonstration, the parts of them being entirely similar, 131.

Reason (a) opp. intuition, 29; opp. experience, 28, 36 n.

(b) Corrects sympathy and senses, 117. No match for nature, 34.

(c) attempts to destroy, by reasoning, 124; objections to abstract reasoning, 124 f. (v. _Scepticism_).

Two kinds of, demonstrative and moral, 30, 46 n, 132; moral, divided into general and particular, 132; produces demonstrations, proofs, and probabilities, 46 n.

Relations of ideas, discoverable by the mere operation of thought, independently of the existence of any object, 20.

Religion a kind of philosophy, 113 (v. _Miracles, Providence_).

Scepticism A. antecedent to study and philosophy, such as Descartes' universal doubt of our faculties, would be incurable: in a more moderate sense it is useful, 116 (cf. 129-30); extravagant attempts of, to destroy reason by reasoning, 124.

No such absurd creature as a man who has no opinion about anything at all, 116; admits of no answer and produces no conviction, 122 n. (cf. 34, 126, 128).

The ordinary criticisms of our senses only show that they have to be corrected by Reason, 117; more profound arguments show that the vulgar belief in external objects is baseless, and that the objects we see are nothing but perceptions which are fleeting copies of other existences, 118; even this philosophy is hard to justify; it appeals neither to natural instinct, nor to experience, for experience tells nothing of objects which perceptions resemble, 119; the appeal to the _veracity of God_ is useless, 120; and scepticism is here triumphant, 121.

_The distinction between primary and secondary qualities_ is useless, for the supposed primary qualities are only perceptions, 122; and Berkeley's theory that ideas of primary qualities are obtained by abstraction is impossible, 122, 122 n; if matter is deprived of both primary and secondary qualities there is nothing left except a mere something which is not worth arguing about, 123.

Attempt to destroy Reason by reasoning extravagant, 124; objection to _abstract reasoning_ because it asserts infinite divisibility of extension which is shocking to common sense, 124, and infinite divisibility of time, 125; yet the ideas attacked are so clear and distinct that scepticism becomes sceptical about itself, 125.

Popular objections to _moral reasoning_ about matter of fact, based on weakness of understanding, variation of judgement, and disagreement among men, confuted by action, 126; philosophical objections, that we only experience conjunction and that inference is based on custom, 127; excessive scepticism refuted by its uselessness and put to flight by the most trivial event in life, 128.

Mitigated scepticism or academical philosophy useful as a corrective and as producing caution and modesty, 129; and as limiting understanding to proper objects, 130; all reasoning which is not either abstract, about quantity and number, or experimental, about matters of fact, is sophistry and illusion, 132.

D. In _Religion_ (v. _Miracles_, _Providence_).

Sciences 132 (v. _Reason_, (d); _Scepticism_, C).

Secret powers, 39; counteracting causes, 47, 67.

Senses outward and inward sensation supplies all the materials of thinking--must be corrected by reason, 117.

Scepticism concerning, 117 (v. _Scepticism_, B).

Similarity basis of all arguments from experience, 31 (cf. 115).

Solidity 50; a supposed primary quality, 122.

Species an effect which belongs to no species does not admit of inference to its cause, 115 (cf. 113).

Theology science of, 132 (v. _God_, _Providence_).

Tillotson argument against real presence, 86.

Understanding limits of human, 7; operations of, to be classified, 8; opp. experience, 28; weakness of, 126 (v. _Reason_, _Scepticism_).

Voluntariness as ground of distinction between virtues and talents, 130.

Whole theory that everything is good as regards 'the whole,' 79, 80.

Will compounds materials given by senses, 13; influence of over organs of body can never give us the idea of power; for we are not conscious of any power in our will, only of sequence of motions on will, 52; so with power of will over our minds in raising up new ideas, 53.

Of God, cannot be used to explain motion, 57.