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Stuff happens, or does it? The puzzle of causation

Unthinkable: Delving into the nature of causes means trying to answer some pretty weird questions

It is very human to confuse correlation with causation. Very human too to project order on random events. Sometimes you just have to accept stuff happens – searching for a reason will always be in vain.

This view within science was famously articulated by the English logician Bertrand Russell when he said “the law of causation… is a relic of a bygone age”.

Russell was speaking about fundamental physics: the laws of nature tell us how things are, not why things are. But his comment acts as a general warning about seeing cause-and-effect where there is none.

Russell was ahead of his time in many matters but, ironically, some philosophers believe what really belongs to “a bygone age” is a general disinterest among scientists in trying to understand fundamental causes, including whatever it was that got natural forces like gravity and magnetism up and running. “The reason why physics has ceased to look for causes is that, in fact, there are no such things,” said Russell.


Just why physicists may have less tolerance for causation talk than philosophers could have something to do with temperament. Scientists prefer to focus on questions for which there are definite answers. As for the other crowd? “We’ll be here for 5,000 years with no answers at all with philosophy,” celebrity physicist Brian Cox once tartly remarked.

Delving into the nature of causes means trying to answer some weird questions. For example, how can a present, which exists, owe its existence to a past that does not exist? Is backward causation possible?

Alison Fernandes, assistant professor in philosophy at Trinity College Dublin, is part of a brave band of academics attempting to give answers. Co-director of the wonderfully-named Irish Society for the Philosophy of Time, she says thinkers in the area generally take either a “physics-based” approach to causation or an “agent-based” approach.

In rough terms, the former tries to explain how causes operate under laws of physics, effectively challenging Russell on his own territory. The latter sidesteps direct confrontation and tries to marry causation with logic, examining how humans, or “agents”, use causes to ensure outcomes they seek.

‘Fundamental physics’

Defending this “agent-based” approach, Fernandes, acknowledges “causation doesn’t get much of a mention in candidate fundamental physical theories”. However, she says there are at least two good reasons to think causation is capable of being explained scientifically.

“First, curiously, pretty much every science that is not fundamental physics, including much of physics itself, is up to its neck in causal talk. Biologists are interested in discovering causal mechanisms. Chemists are interested in the causes of given reactions. If we think that different sciences are related to one another, then it seems we should be able to explain how causal relations in science emerge, in a scientific way, out of sciences that don’t mention causation.

“Second, it has long been argued that causal relations are essential for choosing effective strategies. Say you know that having health insurance and living longer are correlated. That’s not enough to tell you whether having health insurance is a useful means of increasing your longevity – to do that, you need to know whether having health insurance causes people to live longer, or whether the two are merely correlated – say by a higher standard of living causing people to both buy health insurance and live longer.

“It’s plausible to think that the difference between events being merely correlated or causally connected is something that science tells us about – and so what causation is should be explainable in scientific terms.”

So how can cause-and-effect be established scientifically through human deliberation?

Fernandes gives the example of Tamsin who stays dry in a rain shower because she decided to take an umbrella. We can say one caused the other if there is “good evidence” based on probable outcomes.

“By evidence, I don’t just mean that Tamsin thinks she will stay dry if she decides to take her umbrella. I mean that her decision actually raises the chance of her staying dry – so that even someone observing her situation would know she is more likely to stay dry if she decides to take her umbrella.”

Let’s say Tamsin continued to take her umbrella each time it rained, and that she continued to stay dry on each occasion. This could conceivably lead her to conclude that her decision to take an umbrella was the cause of rain. How would we know such reasoning was faulty?

“Not all correlations are causal. In Tamsin’s case, she might notice that it tends to rain whenever she takes her umbrella. But this correlation will only count as causal if Tamsin can use that correlation to raise the chance of outcomes she seeks in an appropriate kind of deliberation,” Fernandes explains.

“There is something distinctly inappropriate about Tamsin deliberating about taking her umbrella to ensure rain when she already has evidence that settles that it will rain.”

Intellectual temperament

Now you may think life is too short to worry about such matters but then 1. you’re reading the wrong newspaper column and 2. you haven’t considered the risks associated with abandoning the search for a scientific basis to causation. Portraying all causes as somehow “unprovable” plays into the hands of those who wish to convince us that facts are just opinions and the truth is whatever you want it to be.

The division between physicists and philosophers on the issue also highlights the role of intellectual temperament in scientific debate.

Studies show mathematicians and physicists are the most atheistic of all academics and it just so happens a “first cause” in fundamental physics would leave open a chink of light for the possibility of a universal creator or God. Could this bias towards atheism help to explain a reluctance among physicists to look behind the curtain of causation?

Fernandes is keen to avoid pitting one set of academics against another but says: “One thing philosophers have long been concerned with is how much our picture of the world is due to how the world is in itself, and how much is shaped by our perspective on the world.

“A similar debate happens in the case of time and causation – how much of the way time and causation are and appear to us is due to features of the world, and how much is due to us and how we engage in the world? Typically, the world-based approach has been associated with being scientifically minded and looking for a physics-based picture of the world.

“Conversely, the agent-based approach has sometimes been associated with a quasi-religious view where we expect the world to be ‘made for us’ or be structured in way that reflects divine agency. But I don’t think those associations are correct.

“If we view matters from a scientific standpoint, it should be obvious that how we picture the world and how we think about it are deeply shaped by our relations to it. There is no ‘view from nowhere’ from which to observe the world.”