Opening the black box

Philosophers of science often argue that an explanation must rest on a general law. To explain an event is to cite a set of initial conditions together with a statement to the effect that whenever those conditions obtain an event of that type follows. In this chapter I offer two objections to this idea, one moderate and relatively uncontroversial, the other more radical and open to dispute.

The first objection is that even if we can establish a general law from which we can deduce the explanandum (the second objection denies that we can always do this), this does not always amount to an explanation. Once again, we may refer to the distinction between explanation on the one hand and correlation and necessitation on the other. A general law to the effect that certain symptoms of a disease are always followed by death may not explain why the person died. A general law based on the fundamental nature of the disease does not explain the death if the disease was preempted by a suicide or a car accident.

To get around these problems, it is often argued that we should replace the idea of a general law with that of a mechanism. Actually, as I use the term “mechanism” in a special sense later, I shall use the phrase “causal chain” to denote what I have in mind here Rather than trying to explain an event E by the statement “Whenever events C1, C2, …, Cn occur, an event of type E follows,” one may try to establish the causal chain that leads from the causes C1, C2, …, Cn, up to E. This step is often referred to as “opening the black box.” Suppose we know that heavy smokers are much more likely than others to get lung cancer. This fact might be due to the fact either that smoking is a cause of lung cancer or that people disposed to smoking also are disposed to the cancer (perhaps genes predisposing for lung cancer are linked to genes that make some people more readily addicted to nicotine). To establish the former explanation, we will have to exhibit a chain of physiological cause-effect relations that begins with heavy smoking and ends with lung cancer.