Let’s start with a very hypothetical stereotype: Cosmologists make bad spouses.
In this world, your mum (and possibly grandma, probably before she died) will warn you from say, age 7, to never date anyone who aspires to be a cosmologist, and she would probably tell you specifically that marrying one should be restricted completely to the realm of day dreaming. Fair enough.
Before we conclude let’s carefully subject your mum’s advice to some rigorous meditations.
First, to conclude that cosmologists make bad spouses, most people will intuitively think about a set of the population – cosmologists that make good spouses, exactly the type anyone will die to marry. Unfortunately in this world, you have to search really hard, as you wouldn’t hear as much of these folks – this is a classic case of silence evidence.
Kindly assume the position of an alien, on your first trip to earth, you got captured by some bunch of barbarians and (unfortunately) got yourself locked up. To put icing on the cake, one of the few privileges you were granted was an unfettered access to the news, the worldwide news.
By the time you manage to escape, you will most likely conclude that all humans are violent. After all, I will be surprised if you hear as much about the peace loving folks on the news –your Muslim buddy whom we can comfortably call an angel; your Parish pastor that pray day and night for his enemies; the Vietnamese Buddhist monk that wouldn’t get angry but, rather, literally smile all day or the Canadian Sikh who has never killed an ant. These are the silent evidences.
In other words, the peace makers that doesn’t make your 10 0’clock news are, indeed, the cosmologists that make good spouses.
Quite irrational, but this makes sense from what we have learnt from cognitive psychology – an angry face is very, very easy to spot in a crowd of happy people, but you will have to try really hard to spot a single happy face among a bunch of angry faces.
Likewise, the mere sight of a single cockroach might screw up your dinner, and possibly, you end up sleeping with an empty stomach, unfortunately a single spoon of your dinner has absolutely no effect on a bunch of cockroaches. Friends, there is an apparent priority for the propagation of bad news, put that in mind.
But it doesn’t stop at that, we can do better.
There are other two sets of the population that are not as intuitive but equally important: People who are not cosmologists that make bad spouse and people who are not cosmologist that make good spouse (I will refer to these group as non-cosmologists, other people in the population minus cosmologists).
If a voodoo doctor on your street approached me and claims to be able to predict the future with edge-bleeding precision, there are 4 sets of data I will be curious to have.
First, I will ask for his track record – 1) what he has predicted that came to past. 2) What he predicted that did not come to past (silent evidence). 3) Events he did not predict that came to past anyways. And even weirder, 4) Events he did not predict that never happened.
Stay with me on this, … let’s switch back to your mum’s advice:
Let us call the number cosmologists that make bad spouse, q
Cosmologists that make good spouse, r
Non-cosmologists that make bad spouse, p
And finally, non-cosmologists that make good spouse, s.
Since we are judging cosmologists comparatively with other people in the world, in order to confirm an association between cosmologists and poor performances in marriage, the following expression must hold: q/r > p/s
That is the ratio of cosmologists that make bad spouse to cosmologists who do not must be greater than the same ratio among non-cosmologists.
Therefore, when q/r > p/s, we will conclude that cosmologist are doing worse compared to the rest of the population when it comes to the marriage business.
On the other hand, when q/r < p/s, we can say that there are more people who are not cosmologists that are doing a very bad job in their marriages compared to cosmologists on a relative basis. From this statistical point of view, mummy and grandma might be wrong.
q/r = p/s Deadlock!
Our social world is complex, we clearly have no capacity to subject every single person we meet to an independent scrutiny, that is why we have stereotypes, to guide us through our decision making process rather rapidly. However, we inherently fall into the trap of generalization during this process.
Therefore it makes perfect sense to stick to our stereotypes when time is an enemy especially when that is coupled with taking highly consequential decisions. In a less-stressed situation, a back-of-the-envelope calculation will most likely not help us (there is simply no such data), however, the logic of these thoughts should make us, at the very least, consider what we might have shoved away as a result of poor thinking about stereotype.