Reasoning with Homo Economicus

The worship of reason is itself an illustration of one of the most long-lived delusions in Western history: the rationalist delusion. It’s the idea that reasoning is our most noble attribute, one that makes us like the gods (for Plato) or that brings us beyond the “delusion” of believing in gods (for the New Atheists). [5, 9]

Beliefs exist because of a need to feel certain and to influence others [5]. The drive for truth can be there, but falling prey to self-righteousness is too easy.  From Plato to Descartes, rationalism promised a superior morality because reason was thought to be free of emotion, pure and transcendent, and separated us from animals.  But rationalists were wrong on all accounts.

Passion Drives Reason

Given Hume’s concerns on the limits of reasoning, he believed that philosophers who tried to reason their way to moral truth without looking at human nature were no better than theologians looking for moral truth in texts. [5]

David Hume knocked down the idol of rationalism with his insight that passion is the driving force behind reason.  In fact, it was insightful enough to get the attention of the rationalist philosopher Kant, who said “Hume woke me from my intellectual stupor”.  Hume was saying that our reasoning is a post hoc rationalization – that is, we make an intuition first and then we justify it.

We may, for example, feel compassion towards those who work for minimum wage but then justify our intuition with a reason such as it being exploitation.  But this flies right in the face of the rational actor model because if our reasoning is anchored in emotion that gives it its direction, then rationality, which is to be emotionless, is not a good description of what it is to be human.

 The rational actor model does not define real rationality. It does not characterize the way people really think, though it is sometimes used as an ideal for how people should think.  [7]

Morality of Self-Interest

Rationality almost always has a moral dimension.  The idea that human rationality is purely mechanical, disengaged, and separable from moral issues is a myth, a myth that is harmful when we live our lives according to it. [7]

The link between rationality and morality may not be obvious, but once we remember that morality is about what we see to be right or wrong and good or bad, all based on some standard, then it shows itself.  Morality, moreover, is usually present when we reason since we justify our reasoning with reasons, and justification itself is an act of determining what is right or wrong.

Think about how much of our reasoning is about morality: it’s better to be strong than to be weak, better to be in control than out of control or dominated by others [7].  What all moral reasoning has in common is that it is about our well-being.  But it is also about others’ well-being, and a consensus that says that we should avoid and prevent harm to others serves our interests too.

That is, morality evolved to put limits on self-interest, and its effects are felt when we realize that many will not have our best interests in mind.  But the folk theory of the “invisible hand” says that self-interest creates wealth for all, so let us equate wealth with well-being and, wallah, we have the pursuit of self-interest as being a moral act that would make us irrational to not follow.

For those who believe in the morality of self-interest, it can never be a moral criticism that one is trying to maximize one’s self-interest, as long as one is not interfering with anyone else’s self-interest.  [7]

Related Posts

Conception of Homo Economicus“: rational man was conceived by way of deductive reasoning and a few “self-evident” truths.

Destruction of Homo Economicus“: rationality from the Enlightenment leads to self-interest and there is no universal reason.

“Reasoning with Homo Economicus: rationality is a form of self-righteousness and passions are what drives reason.

“Resurrection of Homo Economicus: the “invisible hand” promises wealth creation but costs go beyond typical externalities.


[1] Ariely, Dan. Predictably Irrational, Revised and Expanded Edition. HarperCollins e-books.

[2] Barrett, Lisa Feldman. How Emotions Are Made: The Secret Life of the Brain. HMH Books.

[3] Burton, Robert Alan. On Being Certain. St. Martin’s Publishing Group.

[4] Damasio, Antonio R.. Descartes’ Error. Penguin Publishing Group.

[5] Haidt, Jonathan. The Righteous Mind. Knopf Doubleday Publishing Group.

[6] Lakoff, George. Moral Politics. University of Chicago Press.

[7] Lakoff, George. Philosophy In The Flesh.

[8] Lakoff, George. The Political Mind. Penguin Publishing Group.

[9] Mercier, Hugo. The Enigma of Reason. Harvard University Press.

[10] Smith, Justin E. H.. Irrationality. Princeton University Press.

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