An Enquiry Concerning Human Understanding, David Hume [online e book reader TXT] 📗

where different effects have been found to

follow from causes, which are to appearance exactly similar, all these

various effects must occur to the mind in transferring the past to the

future, and enter into our consideration, when we determine the

probability of the event. Though we give the preference to that which

has been found most usual, and believe that this effect will exist, we

must not overlook the other effects, but must assign to each of them a

particular weight and authority, in proportion as we have found it to be

more or less frequent. It is more probable, in almost every country of

Europe, that there will be frost sometime in January, than that the

weather will continue open throughout that whole month; though this

probability varies according to the different climates, and approaches

to a certainty in the more northern kingdoms. Here then it seems

evident, that, when we transfer the past to the future, in order to

determine the effect, which will result from any cause, we transfer all

the different events, in the same proportion as they have appeared in

the past, and conceive one to have existed a hundred times, for

instance, another ten times, and another once. As a great number of

views do here concur in one event, they fortify and confirm it to the

imagination, beget that sentiment which we call belief, and give its

object the preference above the contrary event, which is not supported

by an equal number of experiments, and recurs not so frequently to the

thought in transferring the past to the future. Let any one try to

account for this operation of the mind upon any of the received systems

of philosophy, and he will be sensible of the difficulty. For my part, I

shall think it sufficient, if the present hints excite the curiosity of

philosophers, and make them sensible how defective all common theories

are in treating of such curious and such sublime subjects.

 

SECTION VII.

 

OF THE IDEA OF NECESSARY CONNEXION.

 

PART I.

 

48. The great advantage of the mathematical sciences above the moral

consists in this, that the ideas of the former, being sensible, are

always clear and determinate, the smallest distinction between them is

immediately perceptible, and the same terms are still expressive of the

same ideas, without ambiguity or variation. An oval is never mistaken

for a circle, nor an hyperbola for an ellipsis. The isosceles and

scalenum are distinguished by boundaries more exact than vice and

virtue, right and wrong. If any term be defined in geometry, the mind

readily, of itself, substitutes, on all occasions, the definition for

the term defined: Or even when no definition is employed, the object

itself may be presented to the senses, and by that means be steadily and

clearly apprehended. But the finer sentiments of the mind, the

operations of the understanding, the various agitations of the passions,

though really in themselves distinct, easily escape us, when surveyed by

reflection; nor is it in our power to recal the original object, as

often as we have occasion to contemplate it. Ambiguity, by this means,

is gradually introduced into our reasonings: Similar objects are readily

taken to be the same: And the conclusion becomes at last very wide of

the premises.

 

One may safely, however, affirm, that, if we consider these sciences in

a proper light, their advantages and disadvantages nearly compensate

each other, and reduce both of them to a state of equality. If the mind,

with greater facility, retains the ideas of geometry clear and

determinate, it must carry on a much longer and more intricate chain of

reasoning, and compare ideas much wider of each other, in order to reach

the abstruser truths of that science. And if moral ideas are apt,

without extreme care, to fall into obscurity and confusion, the

inferences are always much shorter in these disquisitions, and the

intermediate steps, which lead to the conclusion, much fewer than in the

sciences which treat of quantity and number. In reality, there is

scarcely a proposition in Euclid so simple, as not to consist of more

parts, than are to be found in any moral reasoning which runs not into

chimera and conceit. Where we trace the principles of the human mind

through a few steps, we may be very well satisfied with our progress;

considering how soon nature throws a bar to all our enquiries concerning

causes, and reduces us to an acknowledgment of our ignorance. The chief

obstacle, therefore, to our improvement in the moral or metaphysical

sciences is the obscurity of the ideas, and ambiguity of the terms. The

principal difficulty in the mathematics is the length of inferences and

compass of thought, requisite to the forming of any conclusion. And,

perhaps, our progress in natural philosophy is chiefly retarded by the

want of proper experiments and phaenomena, which are often discovered by

chance, and cannot always be found, when requisite, even by the most

diligent and prudent enquiry. As moral philosophy seems hitherto to have

received less improvement than either geometry or physics, we may

conclude, that, if there be any difference in this respect among these

sciences, the difficulties, which obstruct the progress of the former,

require superior care and capacity to be surmounted.

 

49. There are no ideas, which occur in metaphysics, more obscure and

uncertain, than those of power, force, energy or _necessary

connexion_, of which it is every moment necessary for us to treat in all

our disquisitions. We shall, therefore, endeavour, in this section, to

fix, if possible, the precise meaning of these terms, and thereby remove

some part of that obscurity, which is so much complained of in this

species of philosophy.

 

It seems a proposition, which will not admit of much dispute, that all

our ideas are nothing but copies of our impressions, or, in other words,

that it is impossible for us to think of any thing, which we have not

antecedently felt, either by our external or internal senses. I have

endeavoured[10] to explain and prove this proposition, and have expressed

my hopes, that, by a proper application of it, men may reach a greater

clearness and precision in philosophical reasonings, than what they have

hitherto been able to attain. Complex ideas may, perhaps, be well known

by definition, which is nothing but an enumeration of those parts or

simple ideas, that compose them. But when we have pushed up definitions

to the most simple ideas, and find still some ambiguity and obscurity;

what resource are we then possessed of? By what invention can we throw

light upon these ideas, and render them altogether precise and

determinate to our intellectual view? Produce the impressions or

original sentiments, from which the ideas are copied. These impressions

are all strong and sensible. They admit not of ambiguity. They are not

only placed in a full light themselves, but may throw light on their

correspondent ideas, which lie in obscurity. And by this means, we may,

perhaps, attain a new microscope or species of optics, by which, in the

moral sciences, the most minute, and most simple ideas may be so

enlarged as to fall readily under our apprehension, and be equally known

with the grossest and most sensible ideas, that can be the object of

our enquiry.

 

[10] Section II.

 

50. To be fully acquainted, therefore, with the idea of power or

necessary connexion, let us examine its impression; and in order to find

the impression with greater certainty, let us search for it in all the

sources, from which it may possibly be derived.

 

When we look about us towards external objects, and consider the

operation of causes, we are never able, in a single instance, to

discover any power or necessary connexion; any quality, which binds the

effect to the cause, and renders the one an infallible consequence of

the other. We only find, that the one does actually, in fact, follow the

other. The impulse of one billiard-ball is attended with motion in the

second. This is the whole that appears to the outward senses. The mind

feels no sentiment or inward impression from this succession of

objects; Consequently, there is not, in any single, particular instance

of cause and effect, any thing which can suggest the idea of power or

necessary connexion.

 

From the first appearance of an object, we never can conjecture what

effect will result from it. But were the power or energy of any cause

discoverable by the mind, we could foresee the effect, even without

experience; and might, at first, pronounce with certainty concerning it,

by mere dint of thought and reasoning.

 

In reality, there is no part of matter, that does ever, by its sensible

qualities, discover any power or energy, or give us ground to imagine,

that it could produce any thing, or be followed by any other object,

which we could denominate its effect. Solidity, extension, motion; these

qualities are all complete in themselves, and never point out any other

event which may result from them. The scenes of the universe are

continually shifting, and one object follows another in an uninterrupted

succession; but the power of force, which actuates the whole machine, is

entirely concealed from us, and never discovers itself in any of the

sensible qualities of body. We know, that, in fact, heat is a constant

attendant of flame; but what is the connexion between them, we have no

room so much as to conjecture or imagine. It is impossible, therefore,

that the idea of power can be derived from the contemplation of bodies,

in single instances of their operation; because no bodies ever discover

any power, which can be the original of this idea.[11]

 

[11] Mr. Locke, in his chapter of power, says that, finding

from experience, that there are several new productions in

nature, and concluding that there must somewhere be a power

capable of producing them, we arrive at last by this reasoning

at the idea of power. But no reasoning can ever give us a new,

original, simple idea; as this philosopher himself confesses.

This, therefore, can never be the origin of that idea.

 

51. Since, therefore, external objects as they appear to the senses,

give us no idea of power or necessary connexion, by their operation in

particular instances, let us see, whether this idea be derived from

reflection on the operations of our own minds, and be copied from any

internal impression. It may be said, that we are every moment conscious

of internal power; while we feel, that, by the simple command of our

will, we can move the organs of our body, or direct the faculties of our

mind. An act of volition produces motion in our limbs, or raises a new

idea in our imagination. This influence of the will we know by

consciousness. Hence we acquire the idea of power or energy; and are

certain, that we ourselves and all other intelligent beings are

possessed of power. This idea, then, is an idea of reflection, since it

arises from reflecting on the operations of our own mind, and on the

command which is exercised by will, both over the organs of the body and

faculties of the soul.

 

52. We shall proceed to examine this pretension; and first with regard

to the influence of volition over the organs of the body. This

influence, we may observe, is a fact, which, like all other natural

events, can be known only by experience, and can never be foreseen from

any apparent energy or power in the cause, which connects it with the

effect, and renders the one an infallible consequence of the other. The

motion of our body follows upon the command of our will. Of this we are

every moment conscious. But the means, by which this is effected; the

energy,