Of course we can predict things

In a recent New York Times opinion piece philosophers Alex Rosenberg and Tyler Curtain argue that economics is not a science because it is not able to predict the state of the economy.

When we put a satellite in orbit around Mars, we have the scientific knowledge that guarantees accuracy and precision in the prediction of its orbit. Achieving a comparable level of certainty about the outcomes of an economy is far dicier. 

The fact that the discipline of economics hasn’t helped us improve our predictive abilities suggests it is still far from being a science, and may never be. Still, the misperceptions persist. A student who graduates with a degree in economics leaves college with a bachelor of science, but possesses nothing so firm as the student of the real world processes of chemistry or even agriculture.

I liked Eric Maskin's reply but the Nobel laureate economist didn't go far enough.

Prediction is certainly a valuable goal in science, but not the only one. Explanation is also important, and there are plenty of sciences that do a lot of explaining and not much predicting. Seismology, for example, has taught us why earthquakes occur, but doesn’t tell Californians when they’ll be hit by “the big one.” 

 And through meteorology we know essentially how hurricanes form, even though we can’t say where the next storm will arise.

Maskin is accepting their flimsy premise that economics can not make predictions. That notion is completely absurd. I'm reminded of something Milton Friedman said as a guest on Icelandic State Television in 1984:

There are certain aspect of economics, as I explained before, which are scientific in character. The quantity theory of money is a scientific law. The statement that inflation is always and everywhere a monetary phenomenon is a scientific law and not a political law. It is like Newton's law. If any country, whether it be a dictatorship or a democracy, whatever it may be, prints too much money you're going to have inflation. If any country, whether it be a dictatorship or a democracy, wants to reduce inflation it must reduce the amount of money it prints. Now those are scientific laws...

The quantity theory of money didn't just happen, it was the result of generations of careful work by economists, and it's extremely good at predicting what happens to the value of money when the ratio changes of currency to goods and services. Economics has countless examples of concepts where we can predict the effect of actions, such as the the impact of price ceilings on production or the effect of  Pigovian taxes on consumption.

The assumption that Rosenberg and Curtain are making is that economics is simply the study of the economy, and since it can't predict complex future events with countless variables it must not be a science after all.

Riddle me this: If we put a stack of 100 unique coins in a closed shoe box and asked a physicist to rattle it around for two minutes, would we expert her to be able to predict which ones will turn out heads-up when the box is opened? Do we expect biologists to be able to predict how evolution will shape a wild species over the next 100,000 years with real-world environmental pressures?

Of course we don't, but too many people want to reject economic science by holding it to an unrealistic standard. Rosenberg and Curtain are missing the entire point, as economics is not the study of the economy. It is the science of the distribution of resources and it does that predictably well.