This article discusses the difference between individual and collective causation, comparing the traditional view that certain causes inevitably lead to certain effects, with the view that causality is only emergent at the collective level.
People believe that for every effect, there is always a corresponding cause. The inevitability of cause and effect can be generalized from individual examples. For example, if person A gets sick from stress, and person B also gets sick from stress, then a general causal conclusion can be drawn from these individual cases: “Stress is the cause of illness.” The causality corresponding to individual cases is called ‘individual-level causality’, and the general causality is called ‘group-level causality’. People have long believed that this group-level causation is inevitable.
One reason for this belief is that the human mind is primarily based on deductive logic. We synthesize individual cases from our experience to derive general laws, and then try to predict future events based on those laws. For example, the law “when it rains, the roads get wet” is derived from observing that the roads get wet in different situations when it rains. This kind of deductive thinking tends to reinforce the inevitability of causation in people. As a result, causal inferences drawn at the collective level have a very high degree of confidence, which is an important basis for people to make decisions in their daily lives.
However, there are those who argue that group-level causation should be viewed as probable, not inevitable. For example, in the statement “stress causes disease,” stress is not a necessary cause of disease, but merely a factor that increases the probability of disease occurring. Even if A and B have a particular illness, at a population level, we can’t say that stress is the cause of that illness. In this way, the relationship between stress and illness is described as causal, not necessary.
It is important to note in this debate that the difference between inevitability and contingency is not simply a probabilistic one. While necessity implies that a particular cause will necessarily lead to a particular effect, contingency implies that a particular cause only increases the likelihood that the effect will occur. So, if we interpret the sentence “Stress is the cause of illness” as a necessity, we would conclude that everyone who is stressed must get sick. On the other hand, a contingent interpretation would lead to the conclusion that stress increases the likelihood of getting sick, but does not necessarily cause it.
Philosophers who hold that individual-level and collective-level causation are independent believe that the two levels of causation must be explained in different ways, because they believe that the complexity and specificity of individual-level causation cannot be explained by collective-level causation. For example, A’s disease may be caused by genetic factors, environmental factors, individual lifestyle habits, and so on, or it may be caused by a combination of these factors acting in a random and complex manner. Given this complexity, causality at the individual level may be a certainty that only applies in certain cases, but it is diluted when extended to the population level.
In contrast, those who argue that individual-level and population-level causation are linked believe that causation is still necessary even if there are multiple factors in an illness. In individual cases, if stress is still an essential factor in an illness when all other factors are considered together, then the inevitability of individual-level causation is not undermined. Correspondingly, the inevitability of group-level causation is not undermined.
In the end, how one interprets individual-level and collective-level causation greatly affects one’s understanding of the cause-and-effect relationship. This debate is not just a philosophical one, but has important practical implications for how we define and interpret causality in scientific research and social policy. For example, when trying to determine the cause of a particular health problem and formulate policy based on it, an approach that presupposes necessary causation and one that presupposes probable causation may lead to very different results.
These discussions are therefore more than just philosophical debates; they are important issues that can have a real impact on our lives.
