Predictions in social sciences 

We often believe prediction in natural sciences is natural while prediction in social sciences is difficult if not impossible. Is it true? We will look at prediction in natural science first.

We can predict the ocean tides ten years from now. But can we predict the location of a particular water molecule in the ocean ten years from now? We can’t. Similarly, we can’t easily predict the fate of a particular person ten years from now. But the general trend of a society may be easier to predict.

We often claim that human actions are difficult to predict because humans have free will. But human actions are driven by their self interest. This is much like ocean tides are driven by gravitational forces from the moon and the sun.  Surely there are random and unpredictable elements in actions of individual persons, just like there are random and unpredictable elements in movements of individual molecules. But the overall movements of the society, just like the overall movements of the tides, are largely predictable.

If human actions are largely predictable, why human society will decline? Aren’t humans have rational expectations? Don’t we make rational decisions? We’ll think about drug use. People use drugs because they bring great short term pleasure, despite the fact of long term harms. At the society level, we often make decisions that benefit the current generation, at the cost of future generations. Japan is the country with highest average age, highest life span and one of the lowest fertility. It may not be an accident that it is also the country with highest government debt/GDP ratio. 

In societies with little central authority, biological instincts determine that fertility remains high. But in societies with powerful central governments, high taxation greatly reduces the ability of working population to support large families. In general, people with fewer or no children have more energy to be involved in politics and therefore dominate political agenda. People with few or no children, less burned out by child care, also tend to live longer. So in societies with powerful central governments, old age welfare generally triumphs young age child rearing. 

In societies with powerful central governments and high taxation, more resources can be concentrated for coordinated use by the governments. So these countries appear to be more powerful on the international stage. Canada and China could not afford two children in each family for their own citizens. Nevertheless, their governments shower money generously overseas to harvest praises and admirations from foreigners and domestic residents who are high on their moral superiority. But all societies with below replacement fertility will eventually decline.

In natural sciences, things that are easier to predict are harder to change. It is easy to predict ocean tides. But it is difficult to change tides. This is because ocean tides are caused by powerful forces, gravitational forces from the moon and the sun. Similarly, in social sciences, things that are easier to predict are harder to change. It is easy to predict the long term consequences of legalization of drug use. But it is difficult to change the tide of events. This is because drug use generate large amount of profits for many powerful social groups. This is why predictions about long term harms of many policies are actively suppressed in mainstream media. The general population are often caught by surprise by the catastrophic events because their predictions are discouraged, discredited and dismissed.