I think rotten's response to this is that it's easy to think that your code is clearer than it really is. I think we can probably all agree with what you've said about your example, but in the real world, the decision may not always be so obvious -- either because it is genuinely a harder question, or because of an oversight. This being the case, maybe it's better to get in the habit of writing even stupid comments (within reason) as well as (of course) eliminating unexpected behavior when possible. This is merely a concession to reality: your code will rarely be perfect, and you will not always have the time/resources/inclination to polish everything the way you might like. But at least if you write a comment, future readers of your code won't be at a disadvantage in fixing your mistakes.