The laws of nature appear to have the following three basic properties.
Do the social sciences have laws? Social scientists sometimes use the language of laws, though perhaps less often than their counterparts in physics. But as we discussed above, we're not interested in how people use language. We're interested in the nature of laws.
To answer whether or not the social sciences have laws, let's warm up with a concrete example. It is among the oldest and most famous statements in economics, called the law of supply and demand.
The law of supply and demand says that the price of a market commodity increases or decreases with the ratio of demand to supply. For example, if there's a fixed supply of the latest cellphone model, and demand increases, then the law says the price of the cellphones will also increase. If there is a fixed demand and the supply increases, for example by over-manufacturing the product, then the price will decrease.
Notice that there are obvious situations in which this rule doesn't work. For example, if the government might regulate a commodity by controlling the price. Then it doesn't matter what the supply or the demand is; the price is always the same. For this reason, one normally says that the law of supply and demand holds, so long as there is a competitive market.
That "so long as" is called hedging. We say that a law is hedged if it is said to be true except for some non-empty list of exceptions.
John Roberts argues that there are no laws in the social sciences. He gives his argument a lovely, clear presentation, of the kind a philosophy essay should always have. It is the following.
John Roberts' Argument Against Social Science Laws
This is clearly a valid argument, meaning that if the premises are true, then the conclusion must also be true. But of course, everything rests on these premises. If Roberts is correct about his premises, then he wins — there are no laws in the social sciences. On the other hand, if even one of his premises is false, then there may yet be laws in the social sciences.
So, let's talk about each of the premises in turn. We'll start with the second one.
The trouble with a hedged law is that it seems to not be very "lawlike" according to the definition we've been considering.
Go back to the law of supply and demand. We noticed one exception to the law. But there are many, many others. Here are just a few exceptions that could be noted.
And there are more. The danger is that, as the list gets longer and longer, we end up with a statement that basically says, the law of supply and demand is true, except when it is not.That's not very lawlike, according to our perspective. In fact, it's a logical tautology — so by definition, it's not a law of nature.
But the situation is worse than that for hedged laws. If "hedging" is allowed in the formulation of laws, then there is a worry that hedged laws cannot be empirically tested. For any exception found to such a law could always be avoided by "hedging."
From the perspective of Karl Popper discussed last week, this is a very bad feature indeed. For if a hedged law cannot be falsified, then it is hard to see how it can be considered a scientific law at all.
We have seen a sense in which the law of supply and demand is extremely hedged. There is a sense in which this is not uncommon. Rather, it appears to be the typical situation in the social sciences.
When we're talking about the facts of anthropology, of political systems, of economies, or of socieities, there always seem to be exceptions to every rule. According to Roberts, this is really an essential fact about the social sciences. The kinds of social structures they deal with always admit exceptions.
John Roberts makes the idea vivid with the following apocalyptic thought experiment. Take any statement that you might think is a law of social science. It will always be hedged, at least a little. This is because it is always possible that a huge meteor (much like the one that created the moon) will smash into the planet and destroy all social structures. The facts of the social sciences must at least hedge against that possibility.
The example is a little extreme. But it's supposed to show a sense in which hedging is inevitable when stating facts about highly contingent structures like societies. Does this kind of hedging really establish that all social laws are hedged as Roberts suggests?
This question, ladies and gentlemen, I leave to you.