Synderesis

Synderesis or synteresis, in scholastic moral philosophy, is the natural capacity or disposition (habitus) of the practical reason to apprehend intuitively the universal first principles of human action.

Reason is a single faculty, but is called differently according to the end that it assigns to its search for truth; when its goal is the mere consideration (contemplation) of truth, it is called speculative reason; when it considers truth in view of action (praxis), it is called practical reason. In both cases reason uses demonstration (syllogism) as its tool; it proceeds from the understanding of previously known truths (premises) to the statement of a proposition (conclusion) whose truth follows necessarily from the premises.