ABSTRACT
Is this argument valid? You might think so. Inverness is a pretty cold place. And wool is plentiful: Scotland has millions of sheep. So surely you may conclude that Fiona must have a woollen jumper or two. Nevertheless, the argument is clearly invalid: it would not be impossible for someone to live in Inverness, yet not have any woollen items of clothing. Indeed, there probably are people there without any (some people are allergic to wool, for example).
