Speculative reason, sometimes called theoretical reason or pure reason, is theoretical (or logical,

deductive Deductive reasoning is the mental process of drawing deductive inferences. An inference is deductively valid if its conclusion follows logically from its premises, i.e. if it is impossible for the premises to be true and the conclusion to be fals ...

) thought, 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 Plato ( ; grc-gre, Πλάτων ; 428/427 or 424/423 – 348/347 BC) was a Greek philosopher born in Athens during the Classical period in Ancient Greece. He founded the Platonist school of thought and the Academy, the first institution ...

and

Aristotle Aristotle (; grc-gre, Ἀριστοτέλης ''Aristotélēs'', ; 384–322 BC) was a Greek philosopher and polymath during the Classical period in Ancient Greece. Taught by Plato, he was the founder of the Peripatetic school of ph ...

, who distinguished between

theory A theory is a rational type of abstract thinking about a phenomenon, or the results of such thinking. The process of contemplative and rational thinking is often associated with such processes as observational study or research. Theories may be ...

(''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 is contemplative, detached, and certain, whereas

practical reason In philosophy, practical reason is the use of reason to decide how to act. It contrasts with theoretical reason, often called speculative reason, the use of reason to decide what to follow. For example, agents use practical reason to decide whethe ...

is engaged, involved, active, and dependent upon the specifics of the situation. Speculative reason provides the universal, necessary principles of logic, such as the principle of non-contradiction, which must apply everywhere, regardless of the specifics of the situation. On the other hand, practical reason is the use of reason to decide how to act. It contrasts with theoretical reason or speculative reason. Some may try and refer to practical reasoning as moral reason but this kind of reasoning actually falls in line more so with theoretical reasoning as it's a contrast of practical reason. This has little to do with what's practical as practicality involves specific action, decision, and particulars which all have a logical undertone without bias toward an ideology. Moral reason finds itself being more malleable in its spectrum of reasoning and had the possibility of being skewed by faith and belief. This will lead to discrepancies in practicality given the nature of morals being a culture specific outlook, and will reduce the practicality in an outcome as each individual has a separate point of view and can change the outcome of moral reasoning. Yet there are philosophers who have erected systems based on this distinction. Two philosophers who have done so are Thomas Aquinas (who follows Aristotle in many respects) and

Immanuel Kant Immanuel Kant (, , ; 22 April 1724 – 12 February 1804) was a German philosopher and one of the central Enlightenment thinkers. Born in Königsberg, Kant's comprehensive and systematic works in epistemology, metaphysics, ethics, and ...

.Karim Mojtahedi, ''Kant's Critical Philosophy'', Tehran: Amir Kabir, 1999

References

{{DEFAULTSORT:Speculative Reason Reasoning Philosophy of Aristotle Concepts in epistemology Concepts in logic Critical thinking Deductive reasoning Epistemology Immanuel Kant Logic Philosophy of logic Platonism Thomas Aquinas Thought