A gentleman thief, a razor and the bias of the obvious

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There are stories that become biases, and because of this we can’t ignore them. As the one of a sophisticated and cultured burglar, more romantic than Bonnie and Clyde, with traits like Houdini, Picasso and Rasputin.

To understand the context, we need to go back to the start of the last century, in New York, where an elegant man, armed with a Colt 9mm, used to enter the banks he would have robbed, asking everyone, politely, calmly and smiling, to raise their hands.

Acute and curious (he read Dante, Shakespeare, Proust and Plato), he managed to collect two million dollars in forty years of robberies, each of them in plain day and without ever shooting. Not little money for those times.

The story of William Francis Sutton, Willie for his friends, however, is not a story with a happy ending. He was sentenced for life, and later released for good conduct and because of lung cancer, that would have taken him away ten years later. The home-made cigarettes which he continuously smoked were to blame. His only vice along with bank robberies.

Sutton’s Law

All of Willie’s life, to get to the point, can be summarized in a sentence: «If they had asked me why I robbed banks, I would have simply answered that “I liked it” and “That’s where the money is”».

This last quote (“That’s where the money is”) has evolved into Sutton’s law (Sutton’s slip bias): to give a medical example, the limit or the fallacy of emphasizing the obvious, that is the most probable diagnosis, rejecting from the start every other alternative (symptom, data, factor). In other terms, it’s the bias that forces you not to take into account elements and data out of the ordinary, worrying about wasting time, money and resources that would be more effective if used elsewhere.

There are stories that become biases, and because of this we can’t ignore them. As the one of a sophisticated and cultured burglar, more romantic than Bonnie and Clyde, with traits like Houdini, Picasso and Rasputin.

Occam’s razor

The juxtaposition with Occam’s razor, at this point, becomes mandatory: “If you hear the sound of hooves, you think of a horse, not a zebra. Unless you live in Africa”. Facing a problem, we don’t always look for the simplest answer, yet it’s the right one in most cases. In other words: with equal elements, the solution of the problem is the most rational one.

Sutton’s law, which justifies bank robberies because that’s where the money is, encourages the doctor, the analyst, the researcher to concentrate on the data that could give the maximum yield, and not to value the probability based on speed or ease with which they can remember analogous examples. On the other hand, Occam’s razor convinces them not to lose themselves in Pindaric flights, in the search of who knows what evidence, if there are no conditions that justify them.

Having recently treated a certain disease can sometimes lead a doctor to consider that disease more common than it really is. Having treated a patient that was affected by a side effect of a drug can lead a doctor to avoid that drug and to fall victim to another insidious effect, the anchoring bias.

Complicating simple things

What the reason suggests is to find a balance, between Sutton’s law and Occam’s razor, remembering that complicating a theory or adding elements in a discussion is useless, if it’s not required to find the solution or make something edifying. Yet it is harmful too, to neglect elements that appear to be incongruent or that cannot explain a certain context, following the logic.

To use this concept in a completely different field, it’s still not really clear how ancient Egyptians managed to build the pyramids: it’s possible that they accomplished it thanks to technologies gifted by an alien civilization, but, if we apply what we have learned so far, it’s preferable to hypothesize that they managed to do it themselves, cleverly taking advantage of the technologies of the time.

In this way, we are not forced to hypothesize a series of particular conditions – the existence of aliens, the fact that they made it to Earth, they communicated with ancient Egyptians and then disappeared without leaving a trace – and anyway, we can explain the same phenomenon resorting to less hypotheses, but more concrete ones.

What we don’t like is not necessarily wrong

The relevance of these two effects is the fact that it forces us to distinguish between what we know and what we don’t know, blocking us from going beyond the simplest possible solution and, at the same time, giving in to the obvious answer. This helps us stay away from presumed knowledge and understand where our theories are incomplete and need to be bettered.

This however does not mean that we can abuse of these effects (as someone ironically calls it, “Occam’s chainsaw”) to shred theories we don’t like to pieces, perhaps because they don’t conform to an arbitrary definition of simplicity or they do not share our premises.

Sometimes, especially in complex fields such as politics or economics, we can see reckless uses of Occam’s razor and Sutton’s effect that give us goosebumps, but in these cases it’s just propaganda and not a good scientific practice.

Laura Mondino

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