Genuine Skepticism may be regarded from two standpoints. 1. In relation to dogma, it is the antithetical habit which suggests investigation—the instinct that spontaneously distrusts both finality and infallibility as ordinary attributes of truth.  It inculcates caution and wariness as against the confidence, presumption, self-complacent assurance of Dogmatists.  Thus interpreted, it is needless to point out the importance of its functions.  A history of doubters and free-thinkers is in fact the history of human enlightenment.  Every advance in thought or knowledge has owed its inception and impulse to inquiring doubt.  Hence it would be idle to deny or attempt to minimize the historical importance of Skepticism, or the perennial antagonism between doubt and dogma — the dynamic and static principles of all human knowledge.

2. Considered in itself Skepticism implies (1) Continuous search, (2) Suspense, or so much of it as is needful as an incentive to search. This is the literal meaning of the word as well as its general signification in Greek philosophy.  We thus perceive that the Skeptic is not the denier or dogmatic Negationist he is commonly held to be.  Positive denial is as much opposed to the true Skeptical standpoint as determinate affirmation.  One as well as the other implies fixity and finality.  Each, when extreme and unconditional, makes a claim to omniscience.  Now it is in order to wean back, if possible, a much-abused philosophical term to its primitive use, as well as to conform to the increasing and true taste of spelling foreign words in their own manner, that the author has adopted in this work the orthography of Skeptic and Skepticism.  Whatever meaning, therefore, his readers may have been accustomed to attach to the more common Sceptic, &c., he [the author] begs them to understand that a Skeptic in these volumes is above all things an inquirer.  He [the Skeptic] is the indomitable, never-tiring searcher after truth …”