Epistemic priority

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When a man throws a ball high in the air and catches it again, he behaves as if he had solved a set of differential equations in predicting the trajectory of the ball. He may neither know nor care what a differential equation is, but this does not affect his skill with the ball. At some subconscious level, something functionally equivalent to the mathematical calculations is going on.

—Richard Dawkins, The Selfish Gene (1976).

We know, however, that the mind is capable of understanding these matters in all their complexity and in all their simplicity. A ball flying through the air is responding to the force and direction with which it was thrown, the action of gravity, the friction of the air which it must expend its energy on overcoming, the turbulence of the air around its surface, and the rate and direction of the ball’s spin. And yet, someone who might have difficulty consciously trying to work out what 3 x 4 x 5 comes to would have no trouble in doing differential calculus and a whole host of related calculations so astoundingly fast that they can actually catch a flying ball.

People who call this “instinct” are merely giving the phenomenon a name, not explaining anything.

—Douglas Adams, Dirk Gently’s Holistic Detective Agency

Epistemic priority
ˈɛpɪˈstiːmɪk praɪˈɒrɪti (n.)

When two competing models appear to explain, account for or manage some phenomenon equally well, a means of deciding, which is the “proper” one.

For example, the trajectory of a missile may be accounted equally well, in theory, for by special relativity, Newtonian mechanics, or the “gaze heuristic”.

Which, all other things being equal, should we prefer? Does one have, as a piece of credentialised technical knowledge about the world, “epistemic priority” over the others?

You may not be surprised to hear opinions tend to divide, cleanly, along magisterial lines, with experts in competing programmes preferring their own. Few experts are agnostic. Epistemic scepticism is left to philosophers. The JC thinks this a pity.

Some domain masters — can we call them that? — will appeal to the related concept of Occam’s razor — a clever heuristic to determine the easiest explanation to go with — but it is just a rule of thumb and has no scientific rigour of its own. A lazy, if useful, fudge but it has no epistemic priority either.

Why does it even matter? If it works, it works, doesn’t it? Some — your correspondent included — would say quite so.

Because scientism

But there is a strand of scientism that sees science as an enterprise converging on “reality”, or “the truth”, and not just “a handy set of tools for the time being”. To their program, progress — betterment against an abstract gold standard — is important: our theories must ascend a grand epistemic staircase towards enlightenment. Those theories that do not help us do that are diverting but, well, literally, diverting. Diversion from the path to enlightenment is at best wasteful and at worst destructive.

Now: how one knows one is on the path to enlightenment is just the question, of course, to which epistemic priority gives an answer. If only we could all agree about it.

On this reductionist theory there is, at the top of that grand staircase (often the metaphor is literally inverted, and the progress described as a descent into structural engineering of the basement, but a “stairway to heaven” seems to us a much better, lordly, and pious image) a grand unifying theory of everything.

When we have that, then what? Well, supporters of the grand unifying theory haven’t carried on that thought experiment. Nirvana? Utopia? Eudaimonia? Game over? Have we clocked the machine and have to start again? Apocalypse?

Let us in any case say that the mysteries of the universe will have been solved, and whatever terrifying joy the universe presented hitherto it will, afterward, feel a bit entropic, warm and brown.

But notice, too, how the idea of the “ultimate solution” — I know, right? — cleaves to rather monomythical ideas about the nature of life: that there are rules, it is bounded, has a running time, a definitive up and down, left and right, start and finish. There is a quest to be resolved. We are players inside a finite game.

If this is right — only if this is right — then epistemic priority is important. Not just for its efficiency, but for the second order connections it vouches safe. For in this universe, all theories must match, mesh and interconnect. They must share the same logic, assumptions and ontology. Since there is but one transcendent truth, every point on every branch of the logic must be correct, lest we throw out the whole machine.

Rather like a proposed crossword solution that for one clue looks right, but later turns out to have been mistaken, and thereby buggers up the rest of the grid, a “useful” but nonetheless wrong theory will lead to trouble down the line if it isn’t rooted out pronto.

Space is big. Really big.

“You might think it's a long way to the chemist, but that’s just peanuts to space”

—Douglas Adams

But the mechanics of the cosmos is no ordinary 15 by 15 grid. Not even a bank holiday jumbo grid. All the engineering must be perfect. There is no tolerance in the system no room for ambiguity or alternative hypothesis. If you commit to reductionism, everything has to be 100% bang-on correct.

But our experience of the history of science has shown that science is anything but 100% bang-on correct. The progress of knowledge from the discovery of fire to the proof of the Biggs hoson is no orchestrated parade to enlightenment. Every theory has succeeded every previous one by conquest.

So to reductionists, epistemic priority is important. Critical to the mission. The slightest internal inconsistency is a killer.

But, problem: on what grounds can we award such priority? Until we find that broken second-order link, then competing models have the same explanatory power. Even if we do find broken link, who is to say whether the present theory or some other one is at fault?

... Or there might be no such thing

I suppose it would be cheeky to invoke Occam’s razor against the the extraordinary conjectures of reductionism. One might make a similar objection to the one Richard Dawkins makes about intelligent design: just because the universe seems to be designed intelligently, that doesn’t mean it is. Likewise, just because the universe seems to behave with regularities and according to consistent principles, that doesn’t mean there is a single clockwork causal mechanism linking all atoms.

To pluralists, pragmatists this is just not a question we have to ask. What does it matter if there is a grand central mechanical schema, if we can never know what it is? All that matters if that you have some tools, rules of thumb and ways of going about the world that work. If your model works, who cares if it is true? Use it.

See also

• Occam’s razor