John Stuart Mill wrote a book many years ago that very few people have read — except maybe his mother and his wife.. . . and me (don’t ask me why). It is a book on inductive logic and scientific method. I learned a number of interesting things in reading the book. For instance I learned that evidence and arguments “imply” conclusions; we “infer” the conclusion from the evidence. In a word, inference is something we do whereas implication is something arguments and evidence do. Further, I learned that points cannot be “valid,” and neither can ideas — though Sheldon Cooper (on “The Big Bang Theory”) keeps insisting they are. Arguments are valid (or invalid) whereas points and ideas can be spot on, insightful, interesting, telling, or perhaps simply stupid — they cannot be “valid.” So you can see my time was not wasted. I dearly love Sheldon Cooper but am delighted to trip him up!
But I also learned something much more interesting, because in his book Mill explained his methods for determining causes. These rules were, respectively, “the “method of similarity” and “the method of difference.” I won’t go into detail, but the former tells us that if you want to know why a group of people got sick at a convention, for example, look for the common denominator — something they all ate or drank. Isolate the item and you can pretty much figure that’s the cause. Years ago it was determined that the cause of a large group of convention-goers getting sick was the ventilating system at their hotel. They all ate and drank different things, but they all breathed the same air.
On the other hand, the method of difference seeks to isolate the causal factor by looking at the one thing that is different in a group that exhibits some strange affliction. Let’s say we want to know why America is such a violent nation. Now we know that there is violence in other countries, but that violence pales in contrast to the frequent violence in this country. Why is that?? Michael Moore made a movie (“Bowling for Columbine”) that attempted to determine the cause and he concluded that it was probably (we can’t be sure) the frequent violence in our news broadcasts. Let’s examine his reasoning.
We begin by comparing and contrasting America with, say, Britain, Japan, and Germany and we look at what the countries have in common: they all watch violent TV, play violent video games, and watch violent movies (often American movies that are known for their violence). Moore thus ruled out those factors as causes of violence in America. What he found was that American news broadcasts are much more violent than the news broadcasts in other developed countries. So he suggested that violence in the news we watch is the likely cause of violence in this country.
This reasoning is sound as far as it goes. But we might just as well pick out coffee as the single factor that separates America from the other countries. In the other three countries tea is the drink of choice; Americans drink a lot of coffee. Or perhaps it’s widespread ownership of guns: Americans own more guns than most other people on earth — except for the Canadians, as I understand it. And the Canadians watch just as much violent TV, movies, and play violent video games. So it can’t be gun ownership. Perhaps it is the violent news programs, as Moore suggested. Or the coffee. Canadians also drink tea as their drink of choice, not coffee. I’m going with coffee.
But then, perhaps it is a combination of the factors listed above. We know that animals learn by imitation and that humans are animals. Further, we know that Americans watch a great deal of violence in their TV, video games, and movies — and their news programs. They also own a great many guns. And they also drink a lot of coffee. So, perhaps, the cause of violence in America is a combination of these factors: the many guns we own together with violence we are exposed to plus the stimulation of a drink spiked with lots of caffeine. You never know! Damn! Causal reasoning is hard.
And yet, there are politicians out there who think it’s easy. They say that the sitting President is the cause of the poor economy because he is the sitting president and the economy is weak. It’s like saying coffee is the cause of violence in America because Americans drink a lot of coffee. And it’s just as stupid.