No Single Mind Can Capture The Truth

It is clear that none of us can know everything. Especially in politics, the extent of individual ignorance is significant. As I argued in a previous series of posts, I suspect that each of us is simply not competent to decide large-scale political issues. To put this in a slightly pretentious slogan, no single mind can capture the truth. A second observation I have stressed is that people strongly, deeply and reasonably disagree about the truth. Even where we do think we have captured the truth, we seriously disagree over what it is.

It’s useful to think about how these two different observations fit together. In some philosophical quarters, there is optimism that intellectual diversity is a good thing, rather than a disadvantage. The idea is that we all possess a different piece of the truth—disagreement indicates that we need to fit these pieces together. Call this the puzzle metaphor. On the puzzle metaphor, it’s not greatly troubling that we disagree and that no single mind can capture the truth, as long as we are decently cooperating in putting the puzzle pieces together. Disagreement is a challenge, but a surmountable one.

The puzzle metaphor is clearly the right general model to think about the epistemic separation of labour in many fields. No single Google engineer, I presume, nowadays understands how the Google search algorithm works, as each only intimately knows a tiny part of the code. No person could design a particle accelerator themselves, or understand the causes of cancer, or develop a full model of the British economy. None of these limitations in individual knowledge fundamentally trouble us, even if the experience of not understanding the whole can be deeply humbling, and sometimes alienating, to individuals: we can build particle accelerators, and we are optimistic that the causes of cancer could in principle be understood.

Indeed, that no individual person can know everything in a given field seems a sign of intellectual maturity. I have heard the claim that Hegel was the last person who had a decent grip on all the major fields of knowledge of his day, before the “knowledge explosion” in the late 19th century. Assuming that this claim is correct, it strikes me less as praise for Hegel, but rather as a damning indictment of the state of science in his day.

If the puzzle metaphor captures the nature of political disagreements, then we wouldn’t need to worry greatly about them—indeed, we should welcome them to a degree. I think that some thinking about disagreement implicitly relies on this model, or something close to it. Ryan Muldoon, for example, argues that “Diversity Is the Solution, Not the Problem”, and invokes a version of the puzzle metaphor:

That we see the world through different perspectives is a wonderful thing, especially if we have any interest in improving ourselves and our societies. It’s for a very simple reason: we simply aren’t smart enough to think through complex problems on our own. There are too many different kinds of considerations, different sources of evidence, different kinds of values that we might want to bring to bear. No single perspective can capture all of that. […] The most fundamental disagreements are the cases through which we can learn the most from one another. We simply can’t pay attention to everything at once—our brains are too small. But as a society we can divide our labor and attention and do just that.

And then there is Jonathan Haidt’s The Righteous Mind. Haidt claims that the moral mind has six “taste buds”, and liberals and conservatives have differently developed taste buds. On the basis of these observations, Haidt jumps to the conclusion that there should be more conservatives in academia. I say “jump”, because it’s not really clear what Haidt’s intermediate steps are to get this conclusion. (John Holbo has written about this extensively on Crooked Timber, and I share the bulk of his worries.)

Something like the puzzle metaphor, I presume, must underlie Haidt’s argument. Here’s one version how we might run the argument (though it might not be Haidt’s): the moral truth comes as six puzzle pieces (“dimensions of taste”, perspectives, elements, etc.). Liberals and conservatives are given different parts of the puzzle; so far from shunning or regretting disagreement, we should try for ways to combine and aggregate these different views. Liberals should welcome and invite disagreement, as it increases our chances to find the truth.

Let’s turn to a second model to think about disagreement. The one theorist who is famous for stressing the importance of ignorance is Hayek. But Hayek, by and large, does not think about ignorance in terms of the puzzle model. Here’s one example of Hayek’s approach to the issue:

Into the determination of […] prices and wages there will enter the effects of particular information possessed by every one of the participants in the market process – a sum of facts which in their totality cannot be known to the scientific observer, or to any other single brain. It is indeed the source of the superiority of the market order, and the reason why, when it is not suppressed by the powers of government, it regularly displaces other types of order, that in the resulting allocation of resources more of the knowledge of particular facts will be utilized which exists only dispersed among uncounted persons, than any one person can possess. But because we, the observing scientists, can thus never know all the determinants of such an order, and in consequence also cannot know at which particular structure of prices and wages demand would everywhere equal supply, we also cannot measure the deviations from that order; nor can we statistically test our theory that it is the deviations from that “equilibrium” system of prices and wages which make it impossible to sell some of the products and services at the prices at which they are offered.

Hayek affirms that no single mind can capture the truth. But it’s not even that we could come up with a way to combine our knowledge and solve the relevant social problems. It’s a difficult philosophical question why Hayek thinks that knowledge cannot be combined in this way. I think the crucial thought is that knowledge is not only dispersed, but also inherently localised. Prices in a market system arise spontaneously on the basis of hundreds of thousands of local interactions. If a central planner or scientist tried to determine the “optimal” price, she would need to gather and process this information, which, Hayek thinks, is impossible.

We can wonder about how metaphysically hard the relevant “impossible” here is, and how deep it philosophically reaches. Part of Hayek’s argument depends, I believe, on the idea that knowledge in the social sciences is reflective. That is, what the social scientist tries to capture is a moving target and subject to being changed by being observed. But we can put these issues aside—Hayek clearly thinks it practically impossible for modern market economies.

Now, the important point is that it makes a difference to your version of liberalism whether you buy into the puzzle piece metaphor in the optimistic form sketched, or the pessimistic, Hayekian version. One plausible upshot of the Hayekian model is that, because knowledge is inherently local, we should disfavour centralised solutions and leave people to their own lights. In the economic realm, this means that we should abstain from centralised economic planning. This is not the necessary upshot if you buy into the more optimistic version of the puzzle metaphor. The optimistic version suggests that correct centralised policy-making will require serious, pluralistic epistemic labour. But in principle, such policy-making is possible: nothing necessarily follows about the badness or inefficiency of central planning, or the central enforcement of morals.

I’m not sure where we should stand on the pessimism—optimism scale. But then again, I am not at all sure that we should think about political disagreement along the puzzle metaphor at all. Think back to a technical problem. Assume that a group of engineers wish to fly to the moon. This technical problem can easily be broken down into a series of mostly modular subproblems: design a propulsion system; design a navigational system; design a landing system; design space suits; and so on. Because of the modularity of the problem, we can be optimistic that a group of people can solve it, even if no single person can.

Some political problems might be like this, especially when it comes to technical problems. Means-ends questions in economic policy-making, for example, we might be able to distribute across different research groups. But if you try to apply the puzzle model in a normative context, it’s less obvious how this could be done. Assume that you’re a libertarian, and I’m a socialist (or the inverse). It is very hard to think, in this context, that we somehow hold different pieces to the same puzzle. Importantly, both of us do not think that we merely have one piece of a larger puzzle, but rather that we’re describing the contours of the whole puzzle in different ways. You think the puzzle depicts a rights-based liberty morality, I believe it shows a solidarity-based vision of equality.

The disagreement between a libertarian a socialist, or a deontologist and a utilitarian, are like the disagreement between someone who believes in Aristotelian physics and someone who believes in modern physics: while these theories describe the same subject matter, they operate in fundamentally different categories. You cannot take a piece from one theory and fit it into the other theory: you must decide between them. At least as far as ideological, large-scale normative disagreements are concerned, this strikes me as a better model to think about them.

This is not to say that disagreement cannot be epistemically fruitful, or that all political disagreements follow this model. We can learn new argument strategies, understand the structure of our own views better, and sometimes be convinced of their fundamental falsity if we engage with others. These are standard liberal points in favour of a free society, but we do not need the puzzle metaphor to make these points.

The puzzle metaphor works if you start from the presumption that value is inherently pluralistic—that the moral truth is a “bit utilitarian, a bit deontological”, or “a bit socialist, a bit libertarian”. Haidt seems to rely on some type of pluralism when he dismisses Kant’s and Bentham’s moral theories quickly as being overly monistic. Many liberals, of course, have flirted with value pluralism as well. If you buy into it, then the puzzle metaphor works—you can have your cake and eat it too: there is truth, and there is disagreement, and disagreement actually brings us closer to the former.

Perhaps. But if value pluralism underlies your argument, then you must argue for it; you cannot simply presume it. Much the same, of course, is true of the Hayekian model, or of the more confrontational model that I favour. The point is that we cannot know a priori which of these three models provides the best background for thinking about disagreement. In much the same way, we cannot know a priori whether conflicting views neatly fit together as so many pieces of the same puzzle. We must be prepared, at least in principle, that they might not.

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