In his monumental masterpiece, A Treatise on Human Nature, which explains the methodology of human reasoning concerning matters of fact and describes the roles that passions and morals play in it, Hume arrives at an enormously interesting maxim: An academic controversy cannot continue for long unless the disputants assign different meanings to the major terms employed in the debate. This theory has been applied in this paper to examine the behavioural criticisms about Homo Economicus (HE), the pivotal perception in the neoclassical microeconomic model.To achieve this objective, the paper discusses the origin and evolution of the concept, reviews behavioural criticisms, summarises the main tenets of Hume's philosophy of human knowledge and finally examines the behavioural opinions from Hume's perspective. The paper concludes that Hume's theory convincingly explains the reason why the HE controversy is continuing for over half century-a fact that both the mainstream and behavioural economists are ignoring.