---
title: "Mental manoeuvres: The Genetic Fallacy"
date: "2007-05-31T11:49:46+01:00"
modified: "2007-05-31T11:49:46+01:00"
url: "https://rationalists.org.uk/articles/mental-manoeuvres-the-genetic-fallacy/"
post_id: 4232
---

# Mental manoeuvres: The Genetic Fallacy

One striking feature of human beings is how bad we are at thinking. That is not to say that with effort and discipline humankind cannot manage some amazing achievements of thought. From Kant’s metaphysics to contemporary theoretical physics, there are many testaments to human intellect. The problem is not that we can’t think well, but that most of the time we don’t think well. This is particularly puzzling because the basic principles of reasoning often look obvious when spelled out. The fundamental rules of logic are no more complex than the basics of arithmetic. This at least provides us with some hope. If we can learn these basic principles and sensitise ourselves to common fallacies and important logical distinctions, perhaps we can nurture better habits of thought, with all the benefits that brings. That hope is what motivates this new series, which will look at some of these principles, distinctions and fallacies and show why they matter for everyday thinking.

Consider, for instance, how one might reason about the following beliefs: Eugenics is a good thing; focus groups can help political parties formulate policies; people generally don’t think well. How do we decide whether each belief is true or false?

Beliefs can be justified in many ways &#150; by our sense experience, by the agreement of authorities, by reasoning soundly from accepted premises and so on. However, seeking these justifications can be time consuming and we are, as psychologists put it, ‘cognitive misers’: we never spend brain power when a less taxing option is available. Cognitive miserliness may have evolved to help us when we face dire situations and careful reasoning would be disastrously slow, but it isn’t a reliable mechanism for discovering truth.

Unfortunately, cognitive miserliness is so ingrained that it creates bad habits that are hard to overcome. One cognitive short-cut many find themselves resorting to is using the origins of a belief as a means of assessing its truth. So, for instance, we know that eugenics started with the Nazis, so there’s a ‘reason’ for saying that it is not a good thing. We know that focus groups started as marketing tools, so there’s a ‘reason’ for saying that political parties that use them are reducing politics to a kind of commerce. We read in New Humanist that people are generally bad at thinking so there’s a ‘reason’ for believing it is true.

These facts about origin clearly do not tell us whether the beliefs are true or false. Eugenics is not necessarily bad just because the Nazis were allegedly the first to practise it, just as encouraging the population to exercise more is not bad because it was something the Nazi government was the first to do on any kind of scale. We don’t think that asking public service users for their feedback is a bad thing just because such user surveys were pioneered in the commercial world, so why should we dismiss focus groups for the same reason? Nor should we think something is true just because we heard it from someone or something we generally admire.

That doesn’t mean the origins of an idea are not worth thinking about. Often the source of a belief provides a clue as to why people believe it or what other beliefs it might be tied up with. It should certainly give us pause for thought that the Nazis had eugenics programmes and that focus groups were designed for business, not government. But what it should not do is make us jump to conclusions about their truth or moral goodness. There is an important distinction which has to be preserved between the origin of an idea and its justification. Ignore this distinction and you commit what is known as the ‘genetic fallacy’.

When you spell out the fallacy it can seem so obvious that we can’t believe we would ever commit it. But the point is that we fall victim to it when we are thinking carelessly, not when we are attending self-consciously and carefully to the logic of our case. And it certainly does seem to be true that the genetic fallacy does infect the thinking of all of us at some time or another. For instance, it is a common misconception about evolutionary psychology that if men have evolved to be promiscuous that somehow justifies their behaviour. Or that the fact that morality has evolved as from a kind of enlightened self-interest means that morality is no more than enlightened self-interest. In both cases, origins are being confused with justifications and the genetic fallacy is committed again. Knowing where a behaviour or a belief has come from can be instructive. But it doesn’t tell you whether it is right or true.