I’ve read a lot of people saying that one thing or another can’t be done and I’ve come to recognize that they mean a number of different things, possibly even contradictory things.
The only things that truly can’t be done are impossible because they violate some fundamental law of nature or because doing so would be a tautological impossibility—impossible by definition. We can’t destroy energy. We can change its form or its state but we can’t destroy it. Or if an inert material is one that doesn’t interact chemically with other materials with which it comes into contact, then, if a material interacts chemically with other materials then it is not inert.
Sometimes when we say that something can’t be done we mean that we don’t know how to do it. In 1960 if we said we can’t go to the moon it would have been true. By July of 1969 it wouldn’t have been true any more.
Sometimes when we say that something can’t be done we mean that the economic, political, social, or other costs of a course of action are more than we believe are acceptable. I’ve written such things myself here at The Glittering Eye. For example, I really believe that if something is politically impossible it’s impossible period. But I really mean two distinct things by that sentence. First, I mean that the political costs are higher than I believe are acceptable and, second, I mean that I can’t imagine any set of circumstances under which that calculus would change.
Sometimes when we say that something can’t be done it’s an act of will: we’re really saying that we don’t want it to happen.
The insidious thing about the latter uses is that circumstances may change and when that happens things that were formerly impossible suddenly become quite possibly, even certain.
Just yesterday I made a comment on someone else’s blog and received quite an angry response. I quickly realized that we were talking at crosspurposes: the author meant something very different by can’t than I did. What he really meant was the third meaning—the costs were higher than he thought were acceptable.
So, when you encounter someone saying or writing that such and such can’t be done or is impossible, ask what does he or she mean by ‘can’t’?
Perhaps there are other things that people mean by can’t but I can’t think of any right now.