I’ve been thinking a lot lately about the value of human life. About the lives so cheaply lost on MH17. About the anger and grief this tragedy has unleashed. About the sense of sacredness and solemn ceremony that followed it. There’s something cathartic about all this. That we mark this with ritual public grieving tells us that these lives – and therefore our own lives – are sanctified; that their termination is an almost blasphemous violation. On some level this reassures us, which is probably why we pore over news coverage of such events, seizing on small harrowing details and the personal stories of the victims.

But I’ve also been thinking a lot about why it is these lives particularly that have earned such a response. The more I heard journalists and politicians talk about how 37 Australians were no longer with us, the stranger it began to sound. Something of that magnitude happens just about every week on our roads, for instance. In the last week for which we have official data, 29 people were killed this way. The youngest was two. We held no ceremonies, and we had no public mourning of the fact that they, too, were no longer with us.

Why? I don’t ask critically, because I’m as unmoved by the road toll as anyone. But it’s surely worth understanding how it is we decide which deaths matter, and which don't; which ones are galling and tragic, and which ones are mere statistics. We tell ourselves we care about the loss of innocent life as though it’s a cardinal, unwavering principle, but the truth is we rationalise the overwhelming majority of it. What does that tell us about ourselves?

Here, the most obvious counterpoint is the nightmare unfolding in Gaza. As I write this, nearly 600 people – overwhelmingly civilians a third of whom are children – have been killed. By the time this goes to print, that number will be redundant. There’s grief, there’s anger and there’s some international hand-wringing, but nothing that compares with the urgency and rage surrounding MH17, even if there is twice the human cost.

If you take your cues from social media, on which this comparison is being relentlessly drawn, the reason is simple: Palestinians are not rich Westerners, and so their lives simply don’t matter. No doubt there’s some truth to this: humans are tribal animals, and we’re as tribal in death as we are in life. But it’s not an entirely satisfactory explanation because it comes from people who would likely exempt themselves from this rule. And yet those same people have almost certainly grieved comparatively little over the thousands of South Sudanese killed in the past six months, or the 1.5 million to have been displaced. Should we conclude they value African lives less than Palestinian ones?