INTELLECTUAL ANTECEDENTS OF SCIENCE 219

taste he has the most absolute certainty possible ; for it

is a fact concerning which Omnipotence itself is powerless

to deceive him. It may be, indeed, that his sensation of

blue is a merely subjective one, and the sourness he tastes

may be occasioned not by what he puts in his mouth,

but by some abnormal condition of his gustatory nerves

or of his brain. That, however, does not make it in the

least the less certain that he has the sensation he feels.

The reality of the fact of the feeling is in no way lessened

by whatever may have been the cause producing it Simi-

larly, he may believe what is the merest delusion, e.g., that

his legs are made of glass, or may doubt what is most

evident to his senses, as that there is light when the sun

is shining at noonday. But none the less, his belief is his

belief while he has it, and so is his doubt, his doubt. Both

are, and can only be, to him just what they are while he

is experiencing them. As to this, he has the most absolute

certainty conceivable, that is, the certainty of both his direct

and his reflex consciousness. He can with full conscious-

ness direct his attention on his own mental state and say,

" I certainly have such a belief, or such a doubt" As to

this, if he thinks about it, no man can really doubt But

a man, nevertheless, may not think of it, and not having

realized that he has a subjective absolute certainty which

nothing can even weaken, he may yet fall into an unreason-

able doubt as to his own mental faculties. Being fully

aware that he has in his life made many mistakes, and that

most men frequently also make them, it is conceivable he

might say to himself, " As my faculties have deceived me

in something, may they not deceive me in everything?

What guarantee have I that they are not always fallacious ?

I cannot get outside myself and compare my convictions

with external realities ; therefore I have no satisfactory

evidence of their truth, and so I really know nothing, and

taste he has the most absolute certainty possible ; for it

is a fact concerning which Omnipotence itself is powerless

to deceive him. It may be, indeed, that his sensation of

blue is a merely subjective one, and the sourness he tastes

may be occasioned not by what he puts in his mouth,

but by some abnormal condition of his gustatory nerves

or of his brain. That, however, does not make it in the

least the less certain that he has the sensation he feels.

The reality of the fact of the feeling is in no way lessened

by whatever may have been the cause producing it Simi-

larly, he may believe what is the merest delusion, e.g., that

his legs are made of glass, or may doubt what is most

evident to his senses, as that there is light when the sun

is shining at noonday. But none the less, his belief is his

belief while he has it, and so is his doubt, his doubt. Both

are, and can only be, to him just what they are while he

is experiencing them. As to this, he has the most absolute

certainty conceivable, that is, the certainty of both his direct

and his reflex consciousness. He can with full conscious-

ness direct his attention on his own mental state and say,

" I certainly have such a belief, or such a doubt" As to

this, if he thinks about it, no man can really doubt But

a man, nevertheless, may not think of it, and not having

realized that he has a subjective absolute certainty which

nothing can even weaken, he may yet fall into an unreason-

able doubt as to his own mental faculties. Being fully

aware that he has in his life made many mistakes, and that

most men frequently also make them, it is conceivable he

might say to himself, " As my faculties have deceived me

in something, may they not deceive me in everything?

What guarantee have I that they are not always fallacious ?

I cannot get outside myself and compare my convictions

with external realities ; therefore I have no satisfactory

evidence of their truth, and so I really know nothing, and