262 THE GROUNDWORK OF SCIENCE

over and above the things which act and react, because it

is invisible as well as intangible. But though our senses

cannot perceive it, our intellect can and does. When we

knock a nail into a board with a hammer, it is simply

nonsense to tell us that because we can only perceive the

nail, the board, and the hammer, we cannot know that we

exert a force which makes the nail go in.

But there is one instance in which a man can be aware,

through his actual feelings, not only of an antecedent and

consequent, and the relation of causality between them, but

also the very bond or nexus between them may be not only

distinctly perceived by our intellect, but its inflow actually

felt. This is whenever a man is in doubt about what course

to pursue owing to his being drawn in different directions

by different motives. Then the inflow and force of the con-

flicting motives acting upon his own mind can be distinctly

perceived by him. This instance is substantially the same

as that we before adduced with respect to our perception of

the emission of " force." We can all also perceive force

when anything resists our will. Thus, let us suppose that

the stem of a small tree has been partly sawn through, and

that we then try whether we can pull it down. If the

coherence of the part not sawn through is still very great,

we may have to exert all our force to overcome it. When

at last we have succeeded, and are exhausted with our efforts,

we may feel very vividly that anyone who denied we had

caused the tree to come down must be as great a lunatic as

anyone who denied the real objective existence of the tree

itself.

But it may be said (we know it may, because such follies

have actually been printed) that, though we may be conscious

of our own force, we err if we assert efficient causation in

any other instance. In fact, Mr. Herbert Spencer has said

that by such an assertion we make the great mistake of

attributing to inanimate things feelings like those we ex-

perience in making such physical efforts. Surely greater

nonsense has rarely been written. Let us suppose the

partly-sawn-through tree to be not even touched by us, but

that a gale has sprung up which, after having swayed it to

and fro, breaks it off, and prostrates it, just as we have

supposed it prostrated by human efforts. Are we not then

to say that the wind has exerted as much force as was ours ?

Can we not say this confidently, without being such idiots as

to attribute " feelings " to the wind ?

Truly, then, we have in our observations and experiments

with external things, as well as in the consciousness of our

own efforts and the action of motives on our minds, actual

experience of causation, while, as we have seen, a very

moderate study of the matter suffices to show us that the

law of causation is a necessary and universal truth which

carries with it its own evidence.

A clear perception of the law of causation gives efficient

support to a great principle, without which all science would

be absolutely impossible. This is the law of the Uniformity

of Nature* It is true that the ordinary experience of man-

kind makes men perfectly contented that things will take

their normal course, e.g. y that the sun will daily rise and set,

and that any tool dropped from the hand will at once fall

towards the ground unless otherwise upheld. In circum-

stances which seem to recur under, so far as we can see, the

same conditions as those wherein they occurred before, we

naturally expect the same results to ensue as we before

met with ; and such expectations are fulfilled.

Nevertheless, mere common sense and human testimony

cannot suffice, any more than the experience of any indi-

vidual can suffice, to show that the uniformity of nature

is, and must always be, positively certain and absolute.

* See ante, p. 1 06.

over and above the things which act and react, because it

is invisible as well as intangible. But though our senses

cannot perceive it, our intellect can and does. When we

knock a nail into a board with a hammer, it is simply

nonsense to tell us that because we can only perceive the

nail, the board, and the hammer, we cannot know that we

exert a force which makes the nail go in.

But there is one instance in which a man can be aware,

through his actual feelings, not only of an antecedent and

consequent, and the relation of causality between them, but

also the very bond or nexus between them may be not only

distinctly perceived by our intellect, but its inflow actually

felt. This is whenever a man is in doubt about what course

to pursue owing to his being drawn in different directions

by different motives. Then the inflow and force of the con-

flicting motives acting upon his own mind can be distinctly

perceived by him. This instance is substantially the same

as that we before adduced with respect to our perception of

the emission of " force." We can all also perceive force

when anything resists our will. Thus, let us suppose that

the stem of a small tree has been partly sawn through, and

that we then try whether we can pull it down. If the

coherence of the part not sawn through is still very great,

we may have to exert all our force to overcome it. When

at last we have succeeded, and are exhausted with our efforts,

we may feel very vividly that anyone who denied we had

caused the tree to come down must be as great a lunatic as

anyone who denied the real objective existence of the tree

itself.

But it may be said (we know it may, because such follies

have actually been printed) that, though we may be conscious

of our own force, we err if we assert efficient causation in

any other instance. In fact, Mr. Herbert Spencer has said

that by such an assertion we make the great mistake of

attributing to inanimate things feelings like those we ex-

perience in making such physical efforts. Surely greater

nonsense has rarely been written. Let us suppose the

partly-sawn-through tree to be not even touched by us, but

that a gale has sprung up which, after having swayed it to

and fro, breaks it off, and prostrates it, just as we have

supposed it prostrated by human efforts. Are we not then

to say that the wind has exerted as much force as was ours ?

Can we not say this confidently, without being such idiots as

to attribute " feelings " to the wind ?

Truly, then, we have in our observations and experiments

with external things, as well as in the consciousness of our

own efforts and the action of motives on our minds, actual

experience of causation, while, as we have seen, a very

moderate study of the matter suffices to show us that the

law of causation is a necessary and universal truth which

carries with it its own evidence.

A clear perception of the law of causation gives efficient

support to a great principle, without which all science would

be absolutely impossible. This is the law of the Uniformity

of Nature* It is true that the ordinary experience of man-

kind makes men perfectly contented that things will take

their normal course, e.g. y that the sun will daily rise and set,

and that any tool dropped from the hand will at once fall

towards the ground unless otherwise upheld. In circum-

stances which seem to recur under, so far as we can see, the

same conditions as those wherein they occurred before, we

naturally expect the same results to ensue as we before

met with ; and such expectations are fulfilled.

Nevertheless, mere common sense and human testimony

cannot suffice, any more than the experience of any indi-

vidual can suffice, to show that the uniformity of nature

is, and must always be, positively certain and absolute.

* See ante, p. 1 06.