I would have thought that speaking about the importance of chance in life would be uncontroversial. My post a few days ago about a new study that was of interest not because the researchers showed the role of chance in getting cancer but that it was more significant than I would have guessed, being responsible about 2/3 of the time, with only 1/3 due to heredity and the environment, something we focus on a lot.

PZ Myers also thought that the role of chance was uncontroversial but he was surprised at the hostile reception the idea received with critics charging that to assign events to chance was somehow unscientific and tantamount to throwing in the towel and embracing ignorance.

Understanding the causes of phenomena is undoubtedly an important part of scientific research. But the cause of something can be due to chance and the closest we can get to assigning a causal mechanism may be a probability distribution of possible outcomes. This is quite uncontroversial in quantum mechanics where the measurement of an event can sometimes only be specified in terms of the probabilities of specific outcomes occurring.

In the paper in question, the authors argued that the probability of a cancerous mutation increased with the number of divisions that a stem cell underwent, since each division had a probability of generating a mutation. So the question is whether those mutations are truly acasual or are caused by factors that are as yet unknown.

The popular misunderstanding about the role of chance may be due to the fact that many everyday events in the classical world that are popularly assigned to chance have presumably identifiable causes if we look closer. The weather is a good example. We assign probabilities to the chance of rain and snow but that is due to our inability to assign precise values to all the parameters that go into weather forecasting, even if we had the ability to do the necessary computations, which we don’t. If I get struck by lightning, was that due to chance or because we have as yet not been able to derive algorithms that can predict the exact time and location of lightning strikes? In the absence of the latter, we are justified in labeling all these things as chance events.

But if we go deeper still, there will be some level where an individual outcome is entirely and intrinsically unpredictable due to the fact that we are dealing with phenomena at the quantum level. But if an individual quantum mechanical event does not play a significant role in the macroscopic outcome, then we can ignore the role of chance and direct causality applies. This is why we are often correct in treating the world as if everything action in it has a discoverable cause.

But in some cases, and cancer is one, an individual microscopic event such as a mutation can cascade and have macroscopic effects, and we ascribe the result of those mutations to chance in that most mutation replicate benignly while the occasional one results in a cancer-causing cell. But are those individual mutations truly random in the quantum mechanical sense or is there some underlying causal mechanism that determines the outcome? I am not a biologist but I suspect that there are many factors involved in cell mutations. For example, ambient radiation while cell division is occurring may cause a dangerous mutation. Some of those factors may be deterministic in principle, though hard to discern and control in practice, while others many be truly quantum mechanically indeterminate in their actions.

But ascribing many things in life to chance is not to be unscientific or to be satisfied with ignorance, as long as we understand the sense in which we are using that word.