IB Philosophy 10.1 Language, Truth and Logic – Alfred Jules Ayer Key Definitions

A posteriori knowledge is knowledge that is justified through sensory experience and empirical observation rather than through pure reasoning alone. The concept, contrasted with a priori knowledge, is central to the analytic/synthetic distinction: while analytic truths hold by definition, synthetic a posteriori truths, such as "water boils at 100 degrees Celsius," require investigation of the world to be confirmed or refuted.

Aesthetic emotivism extends emotivist analysis to judgments about beauty, art, and taste. On this view, statements like 'This painting is beautiful' express the speaker's aesthetic response rather than describing an objective property of the artwork.

The analytic/synthetic distinction divides meaningful propositions into analytic statements, which are true by virtue of meaning alone (e.g. 'all bachelors are unmarried'), and synthetic statements, which are true or false by virtue of how the world is (e.g. 'the cat is on the mat'). Quine challenged and Kripke complicated this division.

Compatibilism is the philosophical position that determinism and free will are compatible. Free will, on this view, requires not the ability to have done otherwise in a strict causal sense, but the ability to act in accordance with one's own reasons and rational deliberation, unimpeded by external constraint.

The cosmological argument is an a posteriori proof for God's existence that reasons from the observable fact that the universe exists and requires a cause to the conclusion that there must be a necessary, uncaused first cause. Versions by Aquinas, Leibniz, and the Islamic kalam tradition differ in detail but share the core claim that an infinite regress of contingent causes is impossible or explanatorily unsatisfying.

Cultural imperialism refers to the imposition of one culture's values, norms, or practices onto other cultures, typically by those in positions of global power. Nussbaum responds to this objection by grounding the capabilities list in cross-cultural dialogue rather than any single cultural tradition.

Emotivism is the meta-ethical theory that moral statements do not express propositions but rather express the speaker's attitudes and attempt to influence others. Saying "stealing is wrong" is not stating a fact but expressing disapproval, sometimes called the "Boo/Hurrah" theory.

Logical positivism is a philosophical movement originating with the Vienna Circle, holding that only statements verifiable through empirical observation or true by definition are meaningful. All other claims, including metaphysics, theology, and normative ethics, are considered literally cognitively meaningless.

Metaphysics is the branch of philosophy concerned with the fundamental nature of reality, including questions about existence, substance, causation, and the relationship between mind and body. Ayer argues that metaphysical statements are cognitively meaningless because they are neither analytic nor empirically verifiable.

Reductionism about the self is the view that the self is not a separately existing entity but can be reduced to patterns of sense experience and bodily states. Ayer argues that 'I' is a logical construction rather than a reference to a soul or substance, drawing on Hume's bundle theory.

Reliabilism is an externalist theory of justification holding that a belief is justified if it is produced by a cognitive process that reliably generates true beliefs. The believer need not be aware of the process's reliability for the belief to count as justified.

Religious experience: any experience in which a person believes they have encountered the divine, the sacred, or a transcendent reality; types include mystical experiences, near-death experiences, prayer, visions, and moments of profound awe or transformation.

a statement that undermines itself when its own criteria are applied to it. The verification principle is charged with self-refutation because the principle itself is neither analytic nor empirically verifiable, and therefore fails its own test for meaningfulness.

Theological non-cognitivism is the view that religious statements such as 'God exists' do not express propositions capable of being true or false. On Ayer's account, this is more radical than atheism, because the claim is not that God does not exist but that the sentence fails to say anything meaningful at all.

The verification principle is the criterion of meaning proposed by logical positivists stating that a non-tautological statement is meaningful only if empirical observations could count for or against it, rendering metaphysical and theological claims devoid of propositional content.