8 THE GROUNDWORK OF SCIENCE

It is thus we apprehend the relations between the various

existences known to us. And the work of science may be

said to consist (i) in the accurate classification of perceived

objects, and the relations which exist between them, both

simultaneous and successive what are often called " the co-

existences and sequences of phenomena" and (2) in

estimating the possibility, probability, necessity, or impossi-

bility of their recurrence. Thus are formulated what are

commonly called " laws of nature." Some of these so-called

" laws " are termed " empirical," because they merely express

co-existences and sequences which have been observed to

exist as facts, apart from any knowledge of the causes which

produce them. Necessary laws, on the other hand, are such

as we can perceive to be the inevitable result of known causes,

or such as possess other evidence of their universal truth.

Some scientific truths must be directly evident (in and through

perception) or science could make no beginning ; but we must

also be able to attain to truths which are indirectly evident

(in and through reasoning or inference), otherwise we could

make no progress, and so science would remain a mere mass

of empirically ascertained data.

Now, amongst the laws of nature are the laws which,

so to speak, regulate the mode in which mental processes

should be carried on in order to secure valid and satisfactory

results and avoid mistakes and fallacies in our judgments

and inferences. Therefore, since science depends, and must

depend, largely on reasoning, it imperatively requires not

only the greatest care with respect to the observation of

facts, but also the greatest care that, in our inferences, those

laws of thought the violation of which induces error, should

in no case be disobeyed.

In every human perception, and therefore of course in every

perception wherewith science is concerned, there are two con-

stituents (i) the mental, or "subjective," constituent the

It is thus we apprehend the relations between the various

existences known to us. And the work of science may be

said to consist (i) in the accurate classification of perceived

objects, and the relations which exist between them, both

simultaneous and successive what are often called " the co-

existences and sequences of phenomena" and (2) in

estimating the possibility, probability, necessity, or impossi-

bility of their recurrence. Thus are formulated what are

commonly called " laws of nature." Some of these so-called

" laws " are termed " empirical," because they merely express

co-existences and sequences which have been observed to

exist as facts, apart from any knowledge of the causes which

produce them. Necessary laws, on the other hand, are such

as we can perceive to be the inevitable result of known causes,

or such as possess other evidence of their universal truth.

Some scientific truths must be directly evident (in and through

perception) or science could make no beginning ; but we must

also be able to attain to truths which are indirectly evident

(in and through reasoning or inference), otherwise we could

make no progress, and so science would remain a mere mass

of empirically ascertained data.

Now, amongst the laws of nature are the laws which,

so to speak, regulate the mode in which mental processes

should be carried on in order to secure valid and satisfactory

results and avoid mistakes and fallacies in our judgments

and inferences. Therefore, since science depends, and must

depend, largely on reasoning, it imperatively requires not

only the greatest care with respect to the observation of

facts, but also the greatest care that, in our inferences, those

laws of thought the violation of which induces error, should

in no case be disobeyed.

In every human perception, and therefore of course in every

perception wherewith science is concerned, there are two con-

stituents (i) the mental, or "subjective," constituent the