Essentialism

Many philosophers object to essentialism. Empiricists like the English philosopher John Locke (1632–1704) reject its a priori postulation of innate ideas or universal truths. They claim that the only preexisting real is the human capacity for sense experience and reflection upon it. Unlike Aristotle, Locke claims that all knowledge originates in sense experience, and the simple ideas derived from our sensations and unmediated thoughts represent the limits of the knowable. Real essences can only be discovered by close empirical observation; all else is idle and potentially dangerous speculation. Every truth claim, including essentialist ones, must be subject to any individual's empirical investigation and verification. Otherwise, objective evaluation of whether such claims actually reflect nothing but the weight of tradition or the power of authority masquerading as truth is impossible.

Modern philosophers, including Karl Popper, extend Locke's rejection of unverifiable claims regarding essences. Rationality demands a skepticism regarding the self-evident existence of anything. For a claim to have truth value, it must be possible to specify conditions under which it can be falsified. These conditions must be translatable into empirical tests that at least conditionally rule out the falsity of the statement. What inter-subjectively verifiable tests could we possibly devise for claims like "humans have a soul," much less that it is our essence?