The Science of Demand (2) - Unofficial Translation of Steven Cheung's 经济解释 - 科学说需求

Section 2.  Facts Not Explainable by Facts

In science, phenomenon, fact, behavior or observation refer to the same thing – though certain phenomena cannot be physically observed.

Explaining a phenomenon often requires the use of non-factual abstract theory. Why should the explanation of a fact involve abstract thinking? The answer is that the regularity of a fact is not self-explanatory. If it rains, there are clouds – this is a regular phenomenon – but the fact that it rains cannot explain the existence of clouds. Wheat grows in soil – this is regularity – but soil cannot explain wheat. The delineation of rights brings economic prosperity – this is regularity, too – but economic prosperity cannot explain the existence of the delineation of property rights; neither is there any explanatory power the other way round. The regularity of facts could only tell us how, but not why.

Suppose phenomenon A leads to phenomenon B, and then we say A explains B, or B explains A, there are two problems. First, there are numerous regular phenomena in the world. If they are really self-explanatory, then there would be voluminous theories in each and every science, and none of them would have any generalized explanatory power. If one phenomenon can explain another phenomenon, then as long as the regularity of a phenomenon is discovered, and we consider the regularity self-explanatory, what would remain in human’s line of reasoning? Second, for a phenomenon exhibiting regularity, the behavior of the regularity may change under different circumstances. For instance, a feather should fall, but may rise when wind is blowing. If wind is used to explain why a feather rises, then why doesn’t a rock ascend under windy condition? What principles should be applied for categorization? The principle we are looking for is a scientific tenet or theory. One application of science, we might say, is to systematically arrange and categorize phenomena.

Karl Brunner said: “Facts cannot be used to explain facts.” Milton Friedman said: “Regularities of facts have to be explained.” In the economics profession, the best quote comes from Alfred Marshall: “All the controversies tell us that unless filtered by rational investigation and interpretation, it is impossible for us to learn anything from facts. This also teaches us that the most reckless and hypocritical people are those theorists who openly profess to let facts do their self-explanation; or unconsciously control the selection and combination of facts behind the scenes, and then put forward the following prediction: since that follows this, this is therefore the reason.”