Via comments on a post at Crooked Timber, an article in the Globe and Mail about a tribe in the Amazon that not only doesn’t have a numbering system, they also don’t have clearly defined words for colors. Adding weirdness to weirdness, they also change their names on a regular basis. The thrust of the article is that the lack of number names interferes with their ability to count. There’s a whole literature in linguistics about this and the larger issue of how language influences thinking, though the subject has fallen into disfavor. I suspect that the truth of the matter is that language severely constrains thought, in that it’s easier to conceptualize things for which you have a word, but does not completely limit it (or where would new words come from? – the concept has to precede the word).

Incidentally, if you’re interested in this question, check out the logical langauge group. They are developing and promoting a language based on formal logic with the explicit intention of exploring the Sapir-Whorf hypothesis.