One feature of vague concepts is that they admit sorites series. A sorites series is a list of cases, where a1 is a case in which it's clear that a particular concept applies, an is a case in which it clearly doesn't, and for some range in the middle it isn't clear either way. In a sorites series about baldness, we'd say that in a1 the man has no hairs; he is clearly bald. In a2, the man has two hairs. In a3, the man has three hairs, and so on. We might end the series with a case in which a man has a million hairs, making him clearly not bald. Somewhere in the middle of the series is a range of cases in which it is not clear that he is bald and not clear that he is not bald. That is to say, it is vague whether he is bald. In the above sorites series, I have described some conditions under which the concept of being bald clearly applies, and I have described some conditions under which the concept clearly does not apply. Whether the concept of being bald applies to a man depends on the number of hairs on his head (and perhaps also on how the hairs are arranged, but for simplicity I will ignore this factor). The concept of being bald clearly applies to the man in the first case, because he has no hairs. The concept of being bald clearly does not apply in the last case, because the man has a great many hairs. It's not clear whether the concept applies to men in the middle cases. Thus, the description of the application conditions for the concept of being bald are not clear. Constructing a sorites series requires that one is able to give a description of a concept's application conditions that is unclear in the above fashion.