Q: I’m not sure whether this question is properly directed to you or to William Safire, but here goes: Is the phrase “root cause” proper English, or is it redundant? Wouldn’t the same meaning be conveyed if “root” were omitted? Or are there different degrees of “cause”?
A: In my opinion (and I can’t speak for Safire), the expression “root cause” isn’t redundant. I think one can argue that there are different levels of causality.
I may have an overly complicated view of all this since I was a philosophy major in college. But I think of causes in at least four different ways—material, formal, efficient, and final causes.
The material cause of something is what it’s made of. A house is “caused” by the wood and other materials it’s built from.
The formal cause is the set of characteristics that make it what it is. A house is “caused” by the fact of its having walls, a roof, rooms, or whatever qualities make it a shelter.
The efficient cause is what brings it into being. A house is “caused” by the builder.
The final cause is the greater purpose or good that it serves. The final “cause” of a house is our need for shelter.
This is an Aristotelian view of “cause.” For many of the same reasons, I think almost anything can be said to have multiple causes. Probably the “root” cause of something is its ultimate purpose. But there are no doubt lesser “causes” along the way that contribute to its coming into existence.
This is a very windy way of answering your question. To paraphrase Pascal, I’ve made it too long because I didn’t have the time to make it shorter.
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