Any of a range of concepts regarding spirituality and religion which do not include the idea of a deity in the form of a theistic god or gods.
Elaboration of theories by use of reason alone without appeal to experience, such as in mathematical systems.
The theory that the reason is a source of knowledge independent of and superior to sense perception.
A view that the fundamental method for problem solving is through reason and experience rather than faith, inspiration, revelation, intuition or authority.
The theory that knowledge may be derived by deductions from a priori concepts (such as axioms, postulates or earlier deductions).