Speculative reason or pure reason is theoretical (or logical, deductive) thought (sometimes called theoretical reason), as opposed to practical (active, willing) thought. The distinction between the two goes at least as far back as the ancient Greek philosophers, such as Plato and Aristotle, who distinguished between theory (theoria, or a wide, bird's eye view of a topic, or clear vision of its structure) and practice (praxis), as well as techne.

Speculative reason or pure reason is theoretical (or logical, deductive) thought (sometimes called theoretical reason), as opposed to practical (active, willing) thought. The distinction between the two goes at least as far back as the ancient Greek philosophers, such as Plato and Aristotle, who distinguished between theory (theoria, or a wide, bird's eye view of a topic, or clear vision of its structure) and practice (praxis), as well as techne.