Hume, Part 2

The dream had turned into a nightmare. So David destroyed the dream.

Hume, Part 2

It’s a dream as old as time - the dream of Reason’s dominion.  In one of the oldest extant works of Western philosophy, for example, Plato bans poets from his Republic because poets lie, because poets bring myths into society, because they are unsettling emissaries from the world beyond Reason.

The dream is still alive; indeed, vibrant. The entire cult of self-optimisation is nothing but an expression of that dream. The apps and the algorithms that promise the ideal partner, the ideal  weight, the ideal career, ultimately, the ideal Self … this is exactly the same dream as the one that inspired Plato. Finally, the mad horses of the passions are to be controlled!

They are mad horses. So let us not mock this dream. Who has not at least once felt that desperate aching desire for peace? Nothing dramatic, nothing extravagant or world-changing - just sweet, blessed peace. Who has not at least once longed for an end to their emotions, for a respite from the turmoil and tumult of their inner world?

David Hume had subscribed, whether he realised it or not, to this dream. That was why he followed the exercises of the classical philosophers, the orderly systematic principles they had laid down for how to live. He had attempted to order himself, his life, according to the dictates of Reason.

And as a direct result, David now had scurvy spots on his fingers, an excessive secretion of saliva in his mouth, and a drowsy numbness that pained his senses.

He had tried to follow the program of life outlined by the great classical philosophers and instead of being blessed with equanimity, with joy, with a serene magnificence, he had found … well, he had found himself writing to a total stranger begging to be rescued.

It hadn’t just been useless to live according to the dictates of Reason (as that was understood by the ancient philosophers), it had been actively harmful. The dream had turned into a nightmare.

So David destroyed the dream.


Yesterday, the sun rose in the east. Where is it going to rise today? In fact, wait: is it going to rise at all???

Is this philosophy?

Indulge me.

Yes, of course it’s going to fucking rise, and yes, it’s going to do so in the east.

Yeah? How do you know that?

Oh, I don’t know … maybe because that’s exactly what’s happened literally every day for a million years?



No, honestly, this is important. Play along and I’ll show you why, I promise.

Okay. On sufferance. Only because I like your smile.

Are you flirting with me?



Are you blushing?


Awww. Cute.

Let’s get back to the sun, okay?

Okay, cap’n.

So. The sun. You think the sun is going to rise in the east tomorrow because that’s how it’s been for the last million years. Being technical, what you’re doing is making an inference - you’re starting from the million years of prior sun-rising, and from that you’re inferring that it will do the same tomorrow.


Now Hume asks: can you justify that inference?

Tell me more, kind Sir!

Alright, well, according to Hume, there are only two types of arguments.

One is what he calls demonstrative reasoning - it may be easier to call it conceptual argument. This type of argument depends purely on how we define the concepts we are using.

For example, the concept of “bachelor” is defined as meaning “unmarried man”. If someone were to say, “My sister is a bachelor”, we could use conceptual argument to demonstrate that they were mistaken. This is why Hume calls it demonstrative reasoning - in this type of argument, you can demonstrate that something is right or wrong.

Can you use conceptual argument to demonstrate the truth of the inference that today’s piece of bread will nourish you? No, says Hume, you cannot. Why not?

Because in conceptual argument, the way and the only way you can establish an inference is by showing that it would be a contradiction to deny the inference. You can establish that your sister is not a bachelor because it would be a contradiction to claim that she is a bachelor.

There is no contradiction in saying: tomorrow the sun won’t rise. So you cannot establish the inference through this type of conceptual argument.

Fine. So now we have the other type of argument. Unsurprisingly, given that this is so often how human beings divide the world, Hume says the alternative to conceptual argument is empirical argument. This is a fancy name for a simple idea - you look at the world, and from it, you make arguments about what is or will be the case.

Can you use empirical argument to establish the inference that the sun will rise tomorrow? No, says Hume, you cannot. Why not?

All empirical argument depends on one key assumption: “that the future will be conformable to the past”.  It is only when we make this assumption that we are able to use what has happened before - i.e. the past - as a guide to what will happen in the future.

But, continues Hume, when we try to make an empirical argument that the sun will rise tomorrow, what we are trying to establish is exactly that the future will be conformable to the past!

So we can’t use empirical argument to establish this, because it would be circular - we would be justifying the claim that the future will be like the past on the basis of the assumption that the future will be like the past.

In order to understand how huge this is, we need to zoom out a bit. In fact, we need to zoom out a lot, all the way to science and the scientific method.

At the most abstract level, science works by finding patterns: when thing A happens, then thing B also happens. For these patterns to be useful, to result in what we call scientific knowledge, we have to be able to rely on them being stable - whenever thing A happens, then thing B will also happen.

In its essence, that’s what a law of nature is: a statement of what will always happen when another thing happens. So for example, an object will remain at rest or in a uniform state of motion unless that state is changed by an external force. That’s a statement of a pattern that is always stable.

What Hume has done, though, is show us that at the bottom of this is an assumption, namely: the future will be like the past. And he has shown us that this assumption cannot be rationally defended. We can believe it, but we cannot rationally argue for it.

Now, science is one of the grand achievements of human reason, and it is where capital-R Reason derives much of its prestige from. What Hume has just told us is: Reason relies on something that cannot be justified with reason. Reason is dependent on assumptions that are not reasonable!

And if we think a moment longer, we will see that it must be so. As soon as we ask, can reason justify itself, we see that the answer must be no - any justification of reason that uses reason will be circular.

Kiss me!

They kiss in a long embrace. Camera fades out.