Kantianism -- any of the three undemonstrable entities (a personal soul, a cosmos, and a supreme being) implicit in the fact of a subject and an object of knowledge, and in the need for some principle uniting them.

idea of pure reason. Dictionary.com. Dictionary.com Unabridged (v 1.1). Random House, Inc. http://dictionary.reference.com/browse/idea of pure reason (accessed: February 18, 2007).