At the risk of building yet another binary, I'd like to suggest a new divide: for those who are curious, and those who are not. In my daily conversations what often makes the most striking impression is not political affiliation or ethical stance, but the degree of curiosity behind the words. Some folk have convictions very close to my own, yet their minds seem closed to the pursuit of truth. They occasionally seek facts but only to bolster their unchanging biases. Others are vehemently opposed to my ideas of society or psyche, yet they remain open to new ideas and impressions.

David Hume, in his Treatise of Human Nature, argued that curiosity is the thrill of mental exertion. This is why those who are curious find no joy in simple addition or the recitation of historical facts: it's not that 40 + 29 doesn't equal 69, or that Caesar didn't cross the Rubicon, but that reception of these truths alone is unchallenging.

Hume also pointed out that curiosity often seeks important truths. Not because these are somehow more exciting, but because this sense of worth aids concentration. "When we are careless and inattentive," Hume wrote, "the same action of the understanding has no effect upon us, nor is able to convey any of that satisfaction". These truths may not actually be epic or greatly practical, and the curious person might be highly misanthropic. But the idea of importance is enough to keep them occupied. The student tells himself his studies of late Heidegger are vital for civilisation but his chief motive is a rightful fascination with the nature of art, for example.

Curiosity, in this light, is neither professional duty nor principled discovery. Certainly someone curious might also be a fine scholar or social reformer: Leonard Woolf comes to mind. But, if Hume's right, curiosity need not have any relationship to professional competency or justice. It is simply a disposition to finding pleasure in mental labour. Sometimes this leads to novels or medicines, other times to a life of quiet but unproductive poking about.

But there is more to Hume's account of curiosity than mental gymnastics. He also contrasts it with gossip. Counterintuitively, Hume suggests that those after scuttlebutt or rumour aren't actually seeking novelty. Instead, they're craving reassurance that neighbours, acquaintances or celebrities are still the same. Most gossip tends to confirm existing prejudices: that things are as we assume; that such-and-such is still a mess, and so-and-so still a living scandal. It is about consolation: that nothing has changed, and we can lean back into the old sagging couch of fact.

Curiosity, by contrast, is slightly more antsy. The curious person hunts for truths but refuses to be satisfied. There are always new doubts or complicating complexities, which give seemingly crisp verities some shading. The point is not that they refuse conclusions, but that they recognise that these are imperfect and partial; that, as AN Whitehead put it, "no fact is merely itself".

It is difficult to make a general case for this curiosity, since its benefits are sometimes for the curious alone. But there are some notes in its favour. Most obviously, to cultivate curiosity — if such a thing is possible — is to gain access to a host of new pleasures: the universe is rich with potential discoveries, even those previously revealed by others. Particle accelerators notwithstanding, it is often relatively cheap too. Curiosity is also a thin bulwark against the totalitarianism mindset, in which all variables must be controlled or eliminated. There is something monstrous about absolute certainty: not only its refusal of others' arguments, but its rejection of the singular human striving to comprehend.

For all its occasional uselessness, curiosity has a dignity that ideologues, of all creeds, lack.

Damon Young is a Melbourne philosopher.