The word certitude indicates both a state of mind and a quality
of a proposition, according as we say, "I am certain", or, "It
is certain". This distinction is expressed in the technical
language of philosophy by saying that there is subjective
certitude and objective certitude. It is worthy of notice, as
regards the use of English terms, that Newman reserves the term
certitude for the state of mind, and employs the word certainty
to describe the condition of the evidence of a proposition.
Certitude is correlative to truth, for truth is the object of
the intellect. Knowledge means knowledge of truth; and hence we
are in the habit of saying simply of a proposition that "it is
certain", to express that it is true, and that its truth is so
evident as legitimately to produce certitude. Certitude is
contrasted with other states of mind in reference to a
proposition: the state of ignorance, the state of doubt, and the
state of opinion. The last-named signifies, in the strict use of
the term, the holding of a propos