The judgment, " not-being is thinkable," cited by Aristotle; the judgment, " A square circle is impossible," cited by Herbart; the judgment, " A centaur is a fiction of the poets," cited by Mill.
The English thinkers influenced by Hegel are inclined to assert mechanism unconditionally, as the very expression of reason - the only thinkable form of order.
Of such primitive principles, the absolutely necessary conditions of possible cognition, only three are thinkable - one perfectly unconditioned both in form and matter; a second, unconditioned in form but not in matter; a third, unconditioned in matter but not in form.
- As Aristotle remarked both in the De Interpretatione and in the Sophistici Elenchi, " not-being is thinkable " does not mean " not-being exists."
But some conceptions are such that the more distinct they are made the more contradictory their elements become; so to change and supplement these as to make them at length thinkable is the problem of the second part of philosophy, or metaphysics.