There’s two reasons why.
The first is novelty. Bombings in Boston don’t happen very often. In countries torn by sectarian violence and in which each sect has bottomless supplies of suicide bombers, bombings are common. So as time goes on it slips further and further down the bulletin.
We call it “the News” and not “the Usuals”, because what gets published is what is unexpected or rare. Headlines like “Grandmother makes it home safely for thousandth time” and “99.99999% of humans not murdered today” are unlikely to see life anywhere but on The Onion.
The second is similarity. We care more about people who are like us. I cared deeply about the death of my grandparents. I cared more about their death than I did about the aftermath of the disintegration of Yugoslavia. And people were then dying in wars in Africa in countries I had never heard of and which I cannot, to this day, reliably point to on a map.
This is not a new observation:
Let us suppose that the great empire of China, with all its myriads of inhabitants, was suddenly swallowed up by an earthquake, and let us consider how a man of humanity in Europe, who had no sort of connexion with that part of the world, would be affected upon receiving intelligence of this dreadful calamity. He would, I imagine, first of all, express very strongly his sorrow for the misfortune of that unhappy people, he would make many melancholy reflections upon the precariousness of human life, and the vanity of all the labours of man, which could thus be annihilated in a moment. He would too, perhaps, if he was a man of speculation, enter into many reasonings concerning the effects which this disaster might produce upon the commerce of Europe, and the trade and business of the world in general. And when all this fine philosophy was over, when all these humane sentiments had been once fairly expressed, he would pursue his business or his pleasure, take his repose or his diversion, with the same ease and tranquillity, as if no such accident had happened.
The most frivolous disaster which could befal himself would occasion a more real disturbance. If he was to lose his little finger to-morrow, he would not sleep to-night; but, provided he never saw them, he will snore with the most profound security over the ruin of a hundred millions of his brethren, and the destruction of that immense multitude seems plainly an object less interesting to him, than this paltry misfortune of his own.
That’s Adam Smith, in a book called The Theory of Moral Sentiments (written before Wealth of Nations), discussing the oddities of human sympathy. Basically, it relies on similarity and proximity.
What most bugs me is when people decide to play morality calculus poker. Oh, you lost two people in a bomb blast? We lost 50. Oh, you lost 50 people in a bomb blast? Last week 100 were hacked to death down our way. Oh, you’re mad about machetes? How about the time …
I use the word “calculus” deliberately, because it reveals a defective mode of thought: that lives can be added and subtracted; that they can be integrated to an area under a blood-soaked curve to determine who has “won” the morality olympics in a kind of more-affronted-than-thou dick-waving contest. I find the whole process of debiting and crediting deaths to be utterly odious. Deaths cannot be subtracted from deaths. Evil is not deductible from evil. Two wrongs don’t make 50 rights.
Incidentally: Mao Tse Tung “wins” the moral calculus olympics. By a wide margin. And if you remove human agency and leave it up to mere events, he in turn is dwarfed by moderately dangerous diseases and so on up the line until you arrive at the fact that no religion, no ideology, no government, no empire, no economic system, no weapon, no army, no dictator and no president have ever killed more people, more horribly, than the passengers of fleas and mosquitoes. And death need not even a byproduct of parasitical life. The spasms of the restless Earth can kill millions in minutes.
So let’s just accept that Americans and westerners will care more about Boston. And that probably hardly anyone in Syria cares about either of them. And that right now people are dying in Africa of malaria at around 5-600 people per day who aren’t in a position to share some dumb bullshit on Facebook.
I see your moral calculus and I raise you the fact that the world sucks and you don’t have to be spiteful pricks about it.