Recent polls have shown that as many as 41% of Americans believe that global warming news is ‘exaggerated,’ which is probably a nice way to say that around 41% of Americans think that the theory of global warming is BS. Not surprisingly to any of my regular blog readers, I am not a climate change skeptic, although before I defend my position in the next weeks I want first to state my dissatisfaction with global warming science.
It doesn’t take a scientist to know that the weather on our planet is not the same as it has been in recent decades. You have only to look at photographs, graphs and tables of melting polar and glacier ice to realize that something is going on – but what? Scientific consensus is that the climate is changing because of greenhouse gas emission, and, as I will explain next week, this is a respectable theory.
But the word ‘because’ is an important word, and it makes all the difference. Philosophers know (and scientists are supposed to know), that cause and effect analyses are quite difficult, even when there is a large sample size. For example, the theory that smoking causes lung cancer was certainly a worthwhile theory when it was first proposed (whenever that was, exactly). But you can’t just conclude that smoking causes lung cancer from one dead smoker, for the simple reason that you must control for variables. For instance, does the brand of cigarette matter? Does the amount smoked per day matter? Does the number of years as a smoker matter? Does the age that the smoker started smoking matter? Does it matter that the smoker lived next to a factory with high vapor admissions? Does it matter whether the smoker also had asthma before he started smoking? And of course, I could go on.
Today we can safely say that we have controlled for a sufficient number of variables to infer that smoking is the cause of lung cancer. But what if our sample size is not millions of smokers, but one single earth? And what if the only member of our sample, the earth, is 4.5 billion years old (our best current estimate)? This wouldn’t be much of an issue, but human beings happen to live for only 80 years or so, making billion year estimates impossible. Scientists tell us that they do have temperature records embedded in ice, but the oldest glaciers are only 800,000 years old.
I think we have to at least admit that these two facts alone significantly complicate any cause/effect analysis, and I would respectfully request that scientists stop using the ‘k – word.’ We human beings know far less than we usually claim.
