CONCEPT
Animal Spirits
Keynes's term for the spontaneous urge to action rather than inaction that drives investment decisions when rational calculation fails — the engine of economic dynamism and the engine of speculative manias.
Animal spirits is Keynes's name for the psychological force that drives entrepreneurial action under conditions of radical uncertainty. Classical economics assumed investment decisions were products of rational calculation — the weighing of expected returns against costs. Keynes demonstrated that such calculation was structurally impossible for genuinely novel investments, because the relevant probabilities could not be derived from any historical frequency. What filled the void where calculation failed was conviction — the gut-level certainty that this venture would succeed. Without animal spirits, no factory gets built; with unchecked animal spirits, speculative manias produce catastrophic collapses. The AI age has amplified animal spirits to unprecedented pitch by reducing the cost of acting on an entrepreneurial impulse to approximately zero.
In The You On AI Field Guide
The concept appears in Chapter 12 of the General Theory, in Keynes's analysis of long-term expectations. It is one of his most original contributions and one of his most widely misunderstood. Critics have treated it as an admission