apodeictic

• It is apodeictic that, while perhaps obscure, words like "skirr" and "periapt" serve uniquely expressive purposes and cannot be subrogated by other, more commonplace words. —  A Gentleman's C
• The categorical imperative which declares an action to be objectively necessary in itself without reference to any purpose, i.e., without any other end, is valid as an apodeictic (practical) principle Whatever is possible only by the power of some rational being may also be conceived as a possible purpose of some will; and therefore the principles of action as regards the means necessary to attain some possible purpose are in fact infinitely numerous. —  Fundamental Principles of the Metaphysic of Morals
• For it is a necessary condition of every cognition that is to be established upon a priori grounds that it shall be held to be absolutely necessary; much more is this the case with an attempt to determine all pure a priori cognition, and to furnish the standard--and consequently an example-- of all apodeictic (philosophical) certitude. —  The Critique of Pure Reason
• For geometrical principles are always apodeictic, that is, united with the consciousness of their necessity, as: "Space has only three dimensions." —  The Critique of Pure Reason
• I shall term this the demonstrative or apodeictic employment of reason. —  The Critique of Pure Reason

Allen's Synonyms and Antonyms