The Core Worldview of Behavioural Finance

The efficient market hypothesis assumes investors are rational. Behavioural Finance spent fifty years demonstrating that they are not — and that the same cognitive errors appear in the same conditions, in the same ways, across cultures and generations. If you understand how human psychology systematically misprice securities, you have an edge that no spreadsheet can replicate.

Why This Matters

Behavioural Finance grew from a collision between economics and psychology. Daniel Kahneman and Amos Tversky, cognitive psychologists at Hebrew University in the early 1970s, began publishing research showing that human beings systematically violate the axioms of rational choice theory — not randomly, but in predictable, documentable ways. Their 1979 paper "Prospect Theory: An Analysis of Decision Under Risk" is the founding document of the field. Richard Thaler brought the insights into financial markets, showing how psychological biases created anomalies that efficient market theory could not explain. Kahneman's 2011 book "Thinking, Fast and Slow" synthesised decades of research into an accessible framework built on two cognitive systems: the fast, automatic, emotionally-driven System 1, and the slow, deliberate, effortful System 2. For investors, Behavioural Finance is not merely interesting — it is directly actionable. The biases it describes — loss aversion, anchoring, confirmation bias, herding — are the mechanisms behind market booms, crashes, and the persistent mispricings that all other schools of investing seek to exploit.