As one well-known saying attributed to Maslow goes, “when all you have is hammer, everything looks like a nail.” If you can only do one thing, you will often apply that thing as a solution to a problem it doesn’t fit particularly well. For example, while a hammer might make for a poor cooking utensil in many cases, if you are tasked with cooking a meal and given only a hammer, you might try to make the best of a bad situation, using the hammer as an inefficient, makeshift knife, spoon, and spatula. That you might meet with some degree of success in doing so does not tell you that hammers function as cooking implements. Relatedly, if I then gave you a hammer and a knife, and tasked with you the same cooking jobs, I would likely observe that hammer use drops precipitously while knife use increases quite a bit. It is also worth bearing in mind that if the only task you have to do is cooking, the only conclusion I’m realistically capable of drawing concerns whether a tool is designed for cooking. That is, if I give you a hammer and a knife and tell you to cook something, I won’t be able to draw the inference that hammers are designed for dealing with nails because nails just aren’t present in the task.
Unless one eats nails for breakfast, that is
While all that probably sounds pretty obvious in the cooking context, a very similar set up appears to have been used recently to study whether third-party punishment (the punishment of actors by people not directly affected by their behavior; hereafter TPP) functions to signal the trustworthiness of the punisher. In their study, Jordan et al (2016) has participants playing a two-stage economic game. The first stage was a TPP game. In this game, there are three players: player A is the helper, and is given 30 cents, player B is the recipient, and given nothing, and player C is the punisher, given 20 cents. The helper can choose to either give the recipient 15 cents or nothing. If the helper decides to give nothing, the punisher then has the option to pay 5 cents to reduce the helper’s pay by 15 cents, or not do so. In this first stage, the first participant would either play one round as a helper or a punisher, or play two rounds: one in the role of the helper and another in the role of the punisher.
The second stage of this game involved a second participant. This participant observed the behavior of the people playing the first game, and then played a trust game with the first participant. In this trust game, the second participant is given 30 cents and decides how much, if any, to send to the first participant. Any amount sent is tripled, and then the first participant decides how much of that amount, if any, to send back. The working hypothesis of Jordan et al (2016) is that TPP will be used a signal of trustworthiness, but only when it is the only possible signal; when participants have an option to send better signals of trustworthiness – such as when they are in the roll of the helper, rather than the punisher – punishment will lose its value as a signal for trust. By contrast, helping should always serve as a good signal of trustworthiness, regardless of whether punishment is an option.
Indeed, this is precisely what they found. When the first participant was only able to punish, the second participant tended to trust punishers more, sending them 16% more in the trust game than non-punishers; in turn, the punishers also tended to be slightly more trustworthy, sending back 8% more than non-punishers. So, the punishers were slightly, though not substantially, more trustworthy than the non-punishers when punishing was all they could do. However, when participants were in the helper role (and not the punisher role), those who transferred money to the recipient were in turn trusted more – being sent an average of 39% more in the trust game than non-helpers – and were, in fact, more trustworthy – returning an average of 25% more than non-helpers. Finally, when the first participant was in the role of both the punisher and the helper, punishment was less common (30% of participants in both roles punished, whereas 41% of participants who were only punishers did) and, controlling for helping, punishers were only trusted with 4% more in the second stage and actually returned 0.3% less.
The final task was less about trust and more about upper-body strength
To sum up, then, when people only had the option to punish others, punishment behavior was used by observers as a cue to trustworthiness. However, when helping was possible as well, punishment ceased to predict trustworthiness. From this set of findings, the authors make the rather strange conclusion that “clear support” was found for their model of punishment as signaling trustworthiness. My enthusiasm for that interpretation is a bit more tepid. To understand why, we can return to my initial example: you have given people a tool (a hammer/punishment) and a task (cooking/a trust game). When they use this tool in the task, you see some results, but they aren’t terribly efficient (16% more trusted and 8% more returned). Then, you give them a second tool (a knife/helping) to solve the same task. Now the results are much better (39% more trusted, 25% more returned). In fact, when they have both tools, they don’t seem to use the first one to accomplish the task as much (punishment falls 11%) and, when they do, they don’t end up with better outcomes (4% more trusted, 0.3% less returned). From that data alone, I would say that the evidence does not support the inference that punishment is a mechanism for signaling trustworthiness. People might try using it in a pinch, but its value seems greatly diminished compared to other behaviors.
Further, the only tasks people were doing involved playing a dictator and trust game. If punishment serves some other purpose beyond signaling trustworthiness, you wouldn’t be able to observe it there because people aren’t in the right contexts for it to be observed. To make that point clear, we could consider other examples. First, let’s consider murder. If I condemn murder morally and, as a third party, punish someone for engaging in murder, does this tell you that I am more trustworthy than someone else who doesn’t punish it themselves? Probably not; almost everyone condemns murder, at least in the abstract, but the costs of engaging in punishment aren’t the same for all people. Someone who is just as trustworthy might not be willing or able to suffer the associated costs. What about something a bit more controversial: let’s say that, as a third party, I punish people for obtaining or providing abortions. Does hearing about my punishment make me seem like a more trustworthy person? That probably depends on what side of the abortion issue you fall on.
To put this in more precise detail, here’s what I think is going on: the second participant – the one sending money in the trust game, so let’s call him the sender – primarily wants to get as much money back as possible in this context. Accordingly, they are looking for cues that the first participant – the one they’re trusting, or the recipient – is an altruist. One good cue for altruism is, well, altruism. If the sender sees that the recipient has behaved altruistically by giving someone else money, this is a pretty good cue for future altruism. Punishment, however, is not the same thing as altruism. From the point of the view of the person benefiting from the punishment, TPP is indeed altruistic; from the point of view of the target of that TPP, the punishment is spiteful. While punishment can contain this altruistic component, it is more about trading off the welfare of others, rather than providing benefits to people per se. While that altruistic component of punishment can be used as a cue for trustworthiness in a pinch when no other information is available, that does not suggest to me sending such a signal is its only, or even its primary function.
Sure, they can clean the floors, but that’s not really why I hired them
In the real world, people’s behaviors are not ever limited to just the punishment of perpetrators. If there are almost always better ways to signal one’s trustworthiness, then TPP’s role in that regard is likely quite low. For what it’s worth, I happen to think that the roll of TPP has more to do with using transient states of need to manage associations (friendships) with others, as such an explanation works well outside the narrow boundaries of the present paper when things other than unfairness are being punished and people are seeking to do more than make as much money as possible. Finding a good friend is not the same thing as finding a good altruist, and friendships do not usually resemble trust games. However, when all you are observing is unfairness and cooperation, TPP might end up looking a little bit like a mechanism for building trust. Sometimes. If you sort of squint a bit.
References: Jordan, K., Hoffman, M., Bloom, P. & Rand. D. (2016). Third-party punishment as a costly signal of trustworthiness. Nature, 530, 473-476.