Till death do us part

Harry and Sophie wanted to take seriously the words the minister would utter as they exchanged rings: “These two lives are now joined in one unbroken circle.” This meant putting their collective interest first, and their individual interests second. If they could do that, the marriage would be better for both of them.

But Harry had seen his own parents divorce and too many friends and relations hurt by betrayal and deceit to accept this unquestioningly. The calculating part of his brain reasoned that if he put himself second but Sophie put herself first, Sophie would get a good deal from the marriage but he wouldn’t. Sophie had similar thoughts…*

This is an example of the prisoners’ dilemma. By individually deciding what to do, Harry and Sophie will insure themselves against the worst possible outcome. To illustrate better, think of it this way: Whether Sophie chooses or not to give her all in the relationship, Harry is better off giving nothing since he avoids the risk of being taken for a mug. In such a context however, the limitation of game theory is salient: by assuming we are all rational, it fails to take into consideration the influence that affect holds over our decisions.

While the first post was a tongue-in-cheek explanation for why we should trust, approaching the topic of trust from a game theoretical perspective is not very appealing (it does seem a bit cold trying to explain feelings using economics). Perhaps then, we should consider alternative reasons for why you should trust your neighbor. Nonetheless, we must realize that the qualitative outcomes as modeled after the prisoners’ dilemma does not change; it is right to suggest that (1) not trusting is a dominant strategy, and (2) the best outcome will be achieved if both co-operate, i.e. trust.

So why should we trust? For obvious reasons, trust is essential in a marriage and a lack of it is a sure recipe for a quick divorce. It’s not hard to see why they should trust; after all, with the exception of some, love is not quite rational. Ask your partner why he or she’s with you and you’ll see why. Just as love does not require a rational explanation, trust in a marriage similarly does not require one (for now).^

The more pressing concern would be: how much should you trust your friends? Different people have different propensities to trust, i.e. willingness to be emotionally and/or physically vulnerable to others. What would be the ideal threshold? Of course, game theory prescribes that to be zero. In fact, you might be skeptical because of bad experiences in the past; you might also know of someone who trusts no one except himself or herself. But while such an approach insures you against getting hurt, it tends to be a self-fulfilling prophecy as well.

While not necessarily so, I think it’s fair to say that there is a high correlation between how much we trust and how we view the world. Generally, we tend to trust more if we see the world as “good”; conversely we prefer to be cynical if we see the world as “bad” or if we’re afraid of getting hurt again. If we view the world as “bad”, we tend to be more guarded and reserved. Whether consciously or unconsciously, we then start treating people differently than how we would if we were to trust them.  Correlation implies causation in this case, giving rise to a self-fulfilling prophecy. This certainly makes it less likely for us to be exploited, but it also means that we’re closing ourselves off from the possibilities for what might be best in life.

Of course, it’d be naive to suggest that we should always trust, or for that matter, that not trusting (and hence treating others differently) is necessarily bad. Consider my misfortune of trusting the person whom I bought my economics textbook from. She advertised the textbook as “condition 10/10, no highlights”, and so I paid her before I even checked it. To my dismay, she was gone by the time I realized the book was scarred with her colorful highlights. In a one-off transaction as such, is there even a need to trust? Not trusting is clearly the better option, since there’s a lot to lose and nothing to gain by trusting (perhaps a few more discounted textbooks in future).

Game theory prescribes strategies resulting in actions, and this leads me to my second reason as to why approaching trust from a game theoretical perspective is not ideal. Trust is not an action: we aren’t doing anything tangible when we decide to trust someone. Trust is more precisely an attitude: our propensity to trust is based largely on how we see the world around us. In fact, we could see our inclination to distrust as simply a defense mechanism that protects us from being exploited. Only time (and a little bit of optimism) can tell us how we should be using this mechanism.

Yours trustfully,


*Adapted from The Pig That Wants To Be Eaten by Julian Baggini.

^As we now see, this is the reason why we need wedding rings. Custom has it that it is a symbol of perfection and never-ending love. Truth be told, it is a strategic move by the groom to indicate to the bride that he’s chosen “to trust”.


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