THE ^fETHODS OF SCIENCE 97

chapter in this book has special reference to the subject

of Epistemology.

Our main object is briefly to call attention to certain ideas,

perceptions, and convictions which are present, in at least

a latent condition, in every method whereby science is

pursued and advanced, and consciously or unconsciously

in the minds of those who pursue it.

The question concerning the intellectual justification of

these ideas, perceptions, and convictions will be entered

upon later.

Now, doubt and scepticism are not only legitimate but

necessary in science. They are safeguards against rash

assent to propositions inadequately proved. True as this

is as regards physical science, it is still more true with regard

to problems that are ultraphysical, in studying which it is

especially necessary to withhold assent from what does not

appear to be clearly and evidently true to our own minds.

Yet it is possible, here as elsewhere, to go from one

extreme to another, and to become so possessed by a

tendency to doubt as to forget the existence and legitimacy

of certainty.

Nevertheless, we all of us possess absolute certainty con-

cerning many things, and this especially applies to those

men who cultivate science. We are all certain that science

has advanced, and that our physical knowledge is greater

in extent and better grounded than it was in the days of

Copernicus. Every man of science is also certain that some

progress is being made in that department to which he is

himself devoted, whatever that may be. But it is obvious

that such advance would be impossible if we could not, by

means of observations, experiments, and reasoning, become

so certain with respect to some facts as to be able to make

them the starting-points for fresh observations and inferences

as to other facts.

H

chapter in this book has special reference to the subject

of Epistemology.

Our main object is briefly to call attention to certain ideas,

perceptions, and convictions which are present, in at least

a latent condition, in every method whereby science is

pursued and advanced, and consciously or unconsciously

in the minds of those who pursue it.

The question concerning the intellectual justification of

these ideas, perceptions, and convictions will be entered

upon later.

Now, doubt and scepticism are not only legitimate but

necessary in science. They are safeguards against rash

assent to propositions inadequately proved. True as this

is as regards physical science, it is still more true with regard

to problems that are ultraphysical, in studying which it is

especially necessary to withhold assent from what does not

appear to be clearly and evidently true to our own minds.

Yet it is possible, here as elsewhere, to go from one

extreme to another, and to become so possessed by a

tendency to doubt as to forget the existence and legitimacy

of certainty.

Nevertheless, we all of us possess absolute certainty con-

cerning many things, and this especially applies to those

men who cultivate science. We are all certain that science

has advanced, and that our physical knowledge is greater

in extent and better grounded than it was in the days of

Copernicus. Every man of science is also certain that some

progress is being made in that department to which he is

himself devoted, whatever that may be. But it is obvious

that such advance would be impossible if we could not, by

means of observations, experiments, and reasoning, become

so certain with respect to some facts as to be able to make

them the starting-points for fresh observations and inferences

as to other facts.

H