Other things being equal, killing two people must be worse than killing one, and killing three people worse than killing two. Right?

But a new study by Loran Nordgren and Mary McDonell, published in Social Psychology and Personality Science, suggests people don’t respond in such a rational way to the scope of a criminal act.

The study finds that people judge criminals who’ve harmed more people less harshly than criminals who’ve harmed fewer people. What’s more they’d punish them less severely. What’s more more, subjects turned out to be less willing to blow the whistle on a crime if there are more victims. What’s more more more, these results were not just produced with hypothetical examples in the laboratory: when the authors examined how juries in the US had reacted in real court cases they discovered a similar pattern. Juries handed out more lenient punishment to those responsible for harming more people.

How are we to make psychological sense of such apparent irrationality? The authors give a plausible explanation. It’s about identifiability: people find it more difficult to identify with many victims than with few. Charities are aware of a similar phenomenon: they often highlight particular case studies – particular individuals in need – rather than simply state the number of people whose condition would be improved by charitable support.

I have no empirical evidence to back me up, but my guess is that this perverse response will only work with certain numbers and under certain conditions. One study conducted by the authors contrasted a crook who defrauded 30 with one who defrauded 3. But presumably, most people will think defrauding two is worse than defrauding one (the identifiability problem will only kick in when the numbers have reached a certain threshold). And most people will judge a person who organized a genocide more harshly than a person who killed one person. (see normblog). So people won’t be impervious to a vast discrepancy in numbers. I guess too that if subjects were taken through a set of cases involving first 4 v 3 victims, then 5 v 3, then 6 v 3, then 7 v3….right up to 30 v 3, they would reach the right conclusion: in other words, that the criminal responsible for the 30 committed the worse deed.

There may also be other factors producing these strange results. For example, in the real-life cases, 30 victims may together be able to afford better legal representation than the 3 victims.

Buf if we accept the thrust of these findings, what are the practical implications? One is this: it is surely an argument for preferring the UK justice system to the US. In the US the jury plays a greater role in setting the sentence. In the UK the jury determines guilt or innocence and the judge fixes the sentence. It may be difficult to counter the irrationality of jurists: but a judge, dealing with such cases all the time, can be trained to be sensitive to and to overcome some very natural, but very illogical conclusions.

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  • Eric says:

    This could motivate a somewhat different hypothesis about the outrage some feel at those who get meagre welfare benefits but ignore the payoffs made by the government to our latest band of financial miscreants. Welfare benefits are small enough that they feel like amounts that could come out of *my* bank account, but the giveaways to the big investment houses are just beyond that kind of comparison.

  • Lina Inverse says:

    “The death of one man is a tragedy, the death of millions is a statistic” (commonly attributed to Stalin).

  • Dennis J. Tuchler says:

    How does the continued utility of the Holocaust fit into this?

  • Peter Wicks says:

    I think the “certain conditions” in David’s post are probably more important than the “certain numbers”. If you ask someone, “Is it worse to kill 10 people or 100?”, obviously they will say 100. So the fact that we tend to act as if the opposite was true when passing judgement in practice clearly implies that different psychological processes are at work depending on whether we are confronted with the question in practice or in the abstract.

    One thing is clear though: the isolated murder of a single (non-famous) individual will never become a historical event like the Holocaust. But that is not to say that we are necessarily more “rational” in assessing historical significance than we are in judging criminals. There are all sorts of (good and less good) reasons why the Holocaust has become a kind of symbol of pure evil, and the numbers involved are only one part of that story.

  • Robin Wilton says:

    The question of relative leniency of punishment is not a straightforward one, either. If you ask someone whether life imprisonment for killing one person is proportionate, they might well say yes. What are they then to say if you ask the appropriate punishment for killing 10 or 100 people…? The idea of proportionality is no longer a useful guide at that point.


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