To propose that human society is governed by laws is generally foolhardy. I wouldn’t object to a Law of Social Laws to push along the lines that all generalizations are false. But this observation has a bit going for it, namely that it depends on the inherent complexity of society, and on human limits. Those are things we can count on.
The law of welfare royalty: Every scheme for categorizing members of a large-scale society will suffer from at least one false positive and at least one false negative.
The law says that every social label will be misapplied in two ways: It will be used to label people it shouldn’t (false positive), and it will fail to be applied to people it should (false negative). Both errors will exist.
The ideas of false positives and false negatives come from signal detection theory, which is about labeling things. If you fired a gun in the direction of someone who might be friend or foe, four things can happen: a good hit, a good miss, a bad hit (friendly fire), and a bad miss.** Failing to keep all four outcomes in mind leads to bad reasoning about humans and society, especially when it comes to news and politics.
- No matter how generous a social welfare system, it will always be possible to find someone suffering from starvation and exposure, and to use their story to argue for more generosity.
- No matter how stingy and inadequate a welfare system, it will always be possible to cry “waste” and “scandal” on some kind of welfare royalty abusing the system.
- No matter the inherent threat of violence from a distant ethnic group, it will always be possible to report a very high and very low threat of violence.
- Airport security measures are all about tolerating a very very high rate of false positives (they search everybody) in order to prevent misses (letting actual terrorists board planes unsearched), but it cannot be guaranteed to succeed, and the cost of searching everybody has to be measured against that.
- In many places, jaywalking laws are only used to shut down public protests. During street protests, jaywalking laws have a 0% hit rate and a 0% correct reject (true negative) rate: they never catch people they should, and they catch all of the people they shouldn’t.
The law of welfare royalty is important for how we think about society and social change. The upshot is that trustworthy reporting about social categories must report using lots of data. Anecdotes will always be available to support any opinion about any act on society. You can also infer from my formulation of the law a corollary that there will always be a talking head prepared to support your opinion, though that isn’t so deep or interesting or surprising.
In fact, none of this is so surprising once a person thinks about it. The challenge is getting a person to think about it, even once. That’s the value of giving the concept a name. If I could choose one facet of statistical literacy to upload into the head of every human being, it would be a native comfort with the complementary concepts of false positives and negatives. Call it a waste of an upload if you want, but signal detection theory has become a basic part of my daily intellectual hygiene.