In the current use both of philosophical and popular language, Certitude is spoken of in a twofold sense. We speak of a belief or conviction of our own minds as possessing the character of Certitude, when it is so strong, and so firmly rooted that it excludes all doubt or hesitation;--we speak also of an object or event as possessing the same character, when it is so presented to our minds as to produce the full assurance of its reality. Hence the distinction between _subjective_ and _objective_ Certitude. The former is a fact of consciousness; it is simply the undoubting assent which we yield to certain judgments, whether these judgments be true or false; it exists in us, and not in the objects of thought; it denotes a condition of our minds, which may, or may not, be in accordance with the actual state of things. The latter is truth or certainty considered _objectively_, as existing in the objects of our knowledge; it is independent of us and of our conceptions; it is _as_ it is, whether it be known or unknown to us; our belief cannot add to its reality, nor can our unbelief diminish or destroy it. Certitude, considered as a mental state, denotes simply the strength of our conviction or belief, as distinguished from doubt or mere opinion; but, considered as an objective reality, it denotes the ground or reason existing in the nature of things for the convictions which we cherish. _Subjective certitude_ is not always the index or the proof of _objective truth_, for men often believe with the strongest assurance what they find reason afterwards to doubt or to disbelieve; and the prevalence of many false beliefs, sincerely cherished and zealously maintained, raises the question, how we may best discriminate between truth and error? Hence the various theories of Certitude, and hence also the antagonist theories of Skepticism. The theories of Certitude may be reduced to _three_ classes. The _first_ places the ground of Certitude in _Reason_; the _second_ in _Authority_; the _third_, in _Evidence_, including under that term both the external manifestations of truth, and the internal principles or laws of thought by which we are determined in forming our judgments in regard to them. Each of these theories, however, has appeared in various phases in the history of philosophical speculation. The Individual Reason of Martineau, the Generic Reason of Lamennais, the Impersonal Reason of Cousin, the Authority of the Race, and the Infallibility of the Church, are specimens of these varieties.