Important trichotomies discussed by Aquinas include the causal principles (agent, patient, act), the potencies for the intellect (imagination, cogitative power, and memory and reminiscence), and the acts of the intellect (concept, judgment, reasoning), with all of those rooted in Aristotle; also the transcendentals of being (unity, truth, goodness) and the requisites of the beautiful (wholeness, harmony, radiance).
Kant expounded a table of judgments involving four three-way alternatives, in regard to (1) Quantity, (2) Quality, (3) Relation, (4) Modality, and, based thereupon, a table of four categories, named by the terms just listed, and each with three subcategories.
Kant also adapted the Thomistic acts of intellect in his trichotomy of higher cognition—(a) understanding, (b) judgment, (c) reason—which he correlated with his adaptation in the soul's capacities—(a) cognitive faculties, (b) feeling of pleasure or displeasure, and (c) faculty of desire[1]—of Tetens's trichotomy of feeling, understanding, and will.
Charles Sanders Peirce built his philosophy on trichotomies and triadic relations and processes, and framed the "Reduction Thesis" that every predicate is essentially either monadic (quality), dyadic (relation of reaction or resistance), or triadic (representational relation), and never genuinely and irreducibly tetradic or larger.
3] מְאֹד (me'od) /Dynamis (power)[6][7] §The list of trichotomies featuring different philosophers was initially influenced by Herb O. Buckland's List which was placed on the Wikipedia years ago but subsequently removed because a complaint was raised about credit not being given to the original author.