A pre-Christmas Lesson on Causation for the PM

In denying the current Australian bushfire crisis is directly caused by climate change, Prime Minister Scott Morrison (and others) take the hair-splitting that has become the norm in Australian political rhetoric to a new level. And it all rests on what is meant when we say that one thing “a cause” of something else. Causation is, you see, a complicated beast to get your head around. Even though quite small babies have a grasp of the idea that one event can generate another—crying brings a caregiver, kicking moves toys in my baby-gym, and so on—causation in a broader sense is rarely that simple. Whilst the cynic in me is pretty sure that the PM knows this and is simply exploiting the vagaries of language for his own political ends, here is a lesson on the nuances of causation and explanation for ScoMo to mull over on his pre-Christmas Hawaiian holiday.

What causes any particular bushfire? Anyone who has tried to start a campfire knows that a spark alone is rarely enough to start a small fire, let alone a big one. What is required is fuel of the right type; the fuel has to be dry; the air can’t be too wet, and so on. Without these “background conditions” in place, one can go through whole boxes of matches without generating anything so much as a whiff of smoke or roasting a single marshmallow. Extending this conclusion to our current predicament, it is trivially true that every bushfire is directly caused by a spark of some sort, whether it be an arsonist’s match or a lightning strike (a fact that I do not wish in any way to downplay). If we want to know, however, why it is that any given spark comes to result in a large scale or out of control bushfire we must look more broadly and think more sophisticatedly about what is meant by an explanation for an event and go beyond mere causes.

Good explanations of events point to those things in the world which philosophers call robust difference makers for those events we want to explain. This is just a fancy philosopher’s way of pointing to those things that together make the outcome of interest highly likely. In the case of a campfire, for example, the robust difference makers are a spark of some sort, dry fuel and low humidity. Whilst the spark is necessary for the fire, it is not by itself usually sufficient for it. Other conditions must hold. In the case of a bushfire, we are (simply speaking) looking at something akin to the campfire. So, whilst the PM is right that it is only the spark that directly causes any one fire, adequately explaining a bushfire requires reference to the other conditions that robustly contribute to fire, such as hot, dry conditions, and the quality and quantity of available fuel. Now, whilst climate change may not be a cause of the spark that starts a fire (though that in itself is debatable), it is definitely a cause of hot, dry conditions and increased fuel quality and quantity. In this sense it is, at a minimum, a key explanation for our current bushfire emergency, and on all but the most restrictive accounts of causation, a cause (albeit, yes, an indirect one) of the fires.

As I said at the outset, the cynic in me suspects our PM is aware of all this and is just splitting-hairs for political gain, but maybe I am wrong. In which case he really does need a lesson on causation for Christmas.