How we meet the future

If we couldn’t make generalisations, we would be paralysed by the world’s complexity. Does that ever excuse stereotyping?

Meet Pippa, the XL Bully. Photo by Christopher Furlong/Getty Images

is the Jacobsen Postdoctoral Fellow at University College London and the Institute of Philosophy, University of London, where he researches the meaning and epistemology of generalisations.

Edited byNigel Warburton

Overgeneralising has a bad rap. It seems an obvious, if understandable, mistake to generalise beyond what our evidence supports. A child playing in the park may assume, based on their experiences of their friendly pet golden retriever, that all dogs are friendly. But they would be wrong to approach an XL Bully, a breed of dog effectively outlawed in the UK recently following a string of attacks on children. When someone makes unwarranted generalisations about social groups, we condemn them for the sin of stereotyping. It is wrong to conclude after just one experience with a rude Brit that all Brits are rude.

We hear less about the problems of undergeneralising. Generalising comes so naturally that few of us are at any risk of undergeneralising, so we give it little thought. The focus on overgeneralising is understandable given its potential costs, such as the child assuming that a dangerous dog is just like the friendly dogs they’ve encountered to date. Generalising itself, though, isn’t a bias that needs to be corrected. It is a cognitive shortcut and a fundamental part of our mental life. We’d be lost without it. It gives our experience structure and frees us up to focus on the new at the expense of the old. The child who approaches the XL Bully and the person who stereotypes Brits risk making a mistake, but the source of their error is not their desire to generalise.

What, then, is wrong with overgeneralising?

Our story begins in Cambridge, 1930. Searching through the papers of his recently deceased friend, the philosopher Richard Braithwaite discovered a sheaf of handwritten notes on the nature of general beliefs, such as the belief that all humans are mortal. The friend was Frank Plumpton Ramsey, the remarkable philosopher and mathematician described as a ‘genius by all tests for genius’ by Paul Samuelson, the Nobel Laureate in economics. The notes were written in September 1929, just four months before Ramsey’s death from a mysterious illness that he may have contracted from swimming in the River Cam. Ramsey died aged just 26 but would go on to leave an oversized legacy in philosophy, mathematics, economics and logic.

In those notes, later titled ‘General Propositions and Causality’ by Braithwaite, Ramsey advocated a view of generalisations that renounced both his own previous views and those of Ludwig Wittgenstein, on whom the young Ramsey, until only recently an undergraduate, exerted a significant influence during their time together in Cambridge in the late 1920s.

Ramsey wanted to know what it means to say that a person believes that all humans are mortal. He concluded that, if you believe a generalisation, you have a habit or disposition. If you believe that all humans are mortal, you will take care not to run over your friends with your car and to make sure they have air to breathe, because you are disposed to treat any human you meet as mortal. Together, these habits and dispositions make up the system with which we ‘meet the future’. They are how we orient ourselves in the face of new observations and experiences.

Two people can disagree in their beliefs about generalisations, even when they agree on all the facts about particulars

What is the alternative? Wittgenstein, with whose writing Ramsey was very familiar, having worked on the translation of the fiendishly cryptic Tractatus Logico-Philosophicus (1921) from German into English while still an undergraduate, had argued that to believe a generalisation is to believe an infinite conjunction of facts about particulars: Alan is mortal and Bella is mortal and Carl is mortal and so on for every human being you could possibly mention. Ramsey’s new view saw beliefs in generalisations as involving a disposition to treat any human you encounter as mortal. That’s a bit different. After all, the disposition is a good one to the extent that it gets things right when tested. The disposition to treat any human I meet as mortal has not led me astray so far, but the disposition to treat any human as having blonde hair would falter quickly. That is why I don’t believe that all humans have blonde hair.

Why did Ramsey reject his earlier view? Ramsey saw that two people can disagree in their beliefs about generalisations, even when they agree on all the facts about particulars. Imagine that I am debating a techno-utopian who believes that mortality is only a contingent feature of humanity’s present existence and that, in principle, humans could live forever. I can agree with them that every human up to now has been mortal, but at the same time disagree over the question of whether all humans are mortal. The techno-utopian would disagree with me that all humans are mortal, even though no human has yet achieved immortality. If believing the generalisation involved believing only that each previous human had been mortal, we could not disagree without disagreeing about a particular human’s mortality. But we agree about all past humans having been mortal. That’s not contested. We disagree only about possible future humans, without disagreeing about any particular human. My disposition to treat humans as mortal would come unstuck in a possible future in which some tech wizard unlocks the secret of immortality. Our disagreement does not concern the facts about the mortality of any actual human, but rather the possible future applications of the disposition.

This new perspective helps to explain why Ramsey revised his earlier view of generalisations. Rather than asking What does the world need to be like for a belief in a........

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