I've just started a linguistics book, and I'd like to get others' opinions on two points that I have reservations about. I get the sense that they may be overstating things a bit in trying to make the case for Universal Grammar. I was going to let this go, but they bring it up elsewhere too. Perhaps theoretically there's no limit on sentence length, but I think there are real limits in practice, which shouldn't be ignored. Even when creating a sentence, where I imagine the theoretical lack of limits is most relevant, I am thinking about keeping the length within certain bounds. Perhaps 'acceptable' sentence length is something we learn through experience? Still, This seems just plain wrong. In what way is it even possible to use and understand an infinite set of sentences? The other point: Is the input really so different and the result really so similar? Are they are using different standards for each? I would think that children learning the same language are exposed to much the same set of utterances. No? If they're talking about across languages, then saying that they all arrive at 'pretty much the same grammar' seems wrong, especially while holding the input to not being 'exactly the same'.