Formal distinction

It was made by some realist philosophers of the Scholastic period in the thirteenth century, and particularly by Duns Scotus.

Scotus argued for a formal distinction (distinctio formalis a parte rei), which holds between entities which are inseparable and indistinct in reality, but whose definitions are not identical.

For example, the personal properties of the Trinity are formally distinct from the Divine essence.

[1] There is also a formal distinction between the divine attributes e.g. love and mercy, and the powers of the soul.

[2] Ockham was opposed to the idea, arguing that whenever there is any distinction or non-identity in reality, then two contradictory statements can be made.