John Stuart Mill coined the term homo economicus to explain economic behavior. This is from . Investopedia:
“Homo economicus, or ‘economic man,’ is the characterization of man in some economic theories as a rational person who pursues wealth for his own self-interest. The economic man is described as one who avoids unnecessary work by using rational judgment. The assumption that all humans behave in this manner has been a fundamental premise for many economic theories.
“The history of the term dates back to the 19th century when John Stuart Mill first proposed the definition of homo economicus. He defined the economic actor as one “who inevitably does that by which he may obtain the greatest amount of necessaries, conveniences, and luxuries, with the smallest quantity of labor and physical self-denial with which they can be obtained.”
“The idea that man acts in his own self-interest often is attributed to other economists and philosophers, like economists Adam Smith and David Ricardo, who considered man to be a rational, self-interested economic agent, and Aristotle, who discussed man’s self-interested tendencies in his work Politics. But Mill is considered the first to have defined the economic man completely.”
Homo economicus says the rational approach to commerce is to seek the most for the least. The idea has its detractors:
“The theory of the economic man dominated classical economic thought for many years until the rise of formal criticism in the 20th century.
“One of the most notable criticisms can be attributed to famed economist John Maynard Keynes. He, along with several other economists, argued that humans do not behave like the economic man. Instead, Keynes asserted that humans behave irrationally. He and his fellows proposed that the economic man is not a realistic model of human behavior because economic actors do not always act in their own self-interest and are not always fully informed when making economic decisions.”
Austrian economist Ludwig von Mises sided with Keynes:
“It was a fundamental mistake … to interpret economics as the characterization of the behavior of an ideal type, the homo economicus. According to this doctrine, traditional or orthodox economics does not deal with the behavior of man as he really is and acts, but with a fictitious or hypothetical image. It pictures a being driven exclusively by ‘economic’ motives, i.e., solely by the intention of making the greatest possible material or monetary profit. Such a being does not have and never did have a counterpart in reality; it is a phantom of a spurious armchair philosophy. No man is exclusively motivated by the desire to become as rich as possible; many are not at all influenced by this mean craving. It is vain to refer to such an illusory homunculus in dealing with life and history.”
More recent criticism questions the role of rationality in human behavior not only in economics but more generally:
“Humanity’s achievements and its self-perception are today at curious odds. We can put autonomous robots on Mars and genetically engineer malarial mosquitoes to be sterile, yet the news from popular psychology, neuroscience, economics and other fields is that we are not as rational as we like to assume. We are prey to a dismaying variety of hard-wired errors. We prefer winning to being right. At best, so the story goes, our faculty of reason is at constant war with an irrational darkness within. At worst, we should abandon the attempt to be rational altogether.
“The present climate of distrust in our reasoning capacity draws much of its impetus from the field of behavioural economics, and particularly from work by Daniel Kahneman and Amos Tversky in the 1980s, summarised in Kahneman’s bestselling Thinking, Fast and Slow (2011). There, Kahneman divides the mind into two allegorical systems, the intuitive ‘System 1’, which often gives wrong answers, and the reflective reasoning of ‘System 2’. ‘The attentive System 2 is who we think we are,’ he writes; but it is the intuitive, biased, ‘irrational’ System 1 that is in charge most of the time.
“Other versions of the message are expressed in more strongly negative terms. You Are Not So Smart (2011) is a bestselling book by David McRaney on cognitive bias. According to the study ‘Why Do Humans Reason?’ (2011) by the cognitive scientists Hugo Mercier and Dan Sperber, our supposedly rational faculties evolved not to find ‘truth’ but merely to win arguments. And in The Righteous Mind (2012), the psychologist Jonathan Haidt calls the idea that reason is ‘our most noble attribute’ a mere ‘delusion’. The worship of reason, he adds, ‘is an example of faith in something that does not exist’. Your brain, runs the now-prevailing wisdom, is mainly a tangled, damp and contingently cobbled-together knot of cognitive biases and fear.
“Although there have been many critics of the theory of homo economicus, the idea that economic actors behave in their own self-interest remains a fundamental basis of economic thought.”
If the shoe doesn’t fit, why do we keep wearing it? And to what end? More next time.
 Investopedia, op cit.
 The image above is from this article.
 Investopedia, op cit.