“Even the statement ‘There are no such things as moral duties’ is a claim about moral duties. There is no neutral position. If I say, ‘Are there any such things as moral duties?’ and you say, ‘No’, you’re not being neutral. You’re making a decision. You’re deciding that rich people have no duty to help poor people. That’s what you’re saying.”

What, I believe, we need to cultivate in explorations of our own nature is the ability to resist being swept away from solid and clear ways of thinking into realms of fantasy, where more or less anything goes.

As Dr Johnson said, argument is like a crossbow: it owes its force to the mechanisms of the bow, as argument owes its force to its intrinsic rational power. But testimony is like the longbow: we cannot tell what it will do unless we know the strength of the user.

The problem with mercenaries can’t simply be that they do what they do for money. It would be pretty hypocritical to condemn them for providing combat services for money, given that we generally honour and praise those members of our nation’s Armed Forces who fight at the front line – even though theyreceive a pay cheque at the end of every month.

It is for Hume’s sympathetic attention to the complexity of human nature, and for his trying to do justice to it at the deepest levels of philosophical refl ection, that we should honour his memory.

He is the darling of naturalism or the bogeyman of scepticism, a friend to virtue or an unwitting party to incipient nihilism. He is politically conservative, or a liberator from old views. He is a fideist, an advocate of faith over reason, or a precursor of Richard Dawkins.

As time moves on, both our philosophical language and our conceptual frameworks evolve, since they are highly abstract and not closely tethered to the relatively solid ground of ordinary life. So to understand Hume’s thinking, it becomes necessary to “translate” what he says into categories increasingly different from his own.

Many philosophers came to regard “causation” as an illegitimate pseudo-concept. This was a dominant view in analytic philosophy until quite late in the twentieth century. Russell famously quipped that “the law of causality” was “a relic of a bygone age, surviving, like the monarchy, only because it is erroneously supposed to do no harm”.

Popular religions are practical; they are used as guides to living. But philosophical religion has no implications for how we should live. Hume thought that philosophical theism and popular monotheism cannot be coherently united. Yet incoherent unification is precisely what has happened in our own culture.

A radical implication of Hume’s theory of motivation is that it makes no sense, strictly speaking, to call actions rational or irrational. So, he claims, it is not contrary to reason for me to prefer the destruction of the world to getting a scratch on my finger.

We might be inclined to think of the mind as a kind of theatre in which our thoughts and feelings – or “perceptions” – make their appearance; but if so we are misled, for the mind is constituted by its perceptions.

The hacker culture is neither good nor evil, but instead focuses on getting results. It is self-reliant and rooted in an anti-authoritarian embrace of individuality. No citizen is beholden to any single person, only to the quality of work being done.