Wisdom, sapience, or sagacity is the ability to contemplate and act productively using knowledge, experience, understanding, common sense, and insight. Wisdom is associated with attributes such as unbiased judgment, compassion, experiential self-knowledge, self-transcendence, and non-attachment, and virtues such as ethics and benevolence.

Knowledge is an awareness of facts, a familiarity with individuals and situations, or a practical skill. Knowledge of facts, also called propositional knowledge, is often characterized as true belief that is distinct from opinion or guesswork by virtue of justification. While there is wide agreement among philosophers that propositional knowledge is a form of true belief, many controversies focus on justification. This includes questions like how to understand justification, whether it is needed at all, and whether something else besides it is needed. These controversies intensified in the latter half of the 20th century due to a series of thought experiments called Gettier cases that provoked alternative definitions.