Another way of expressing the fallacy is in the argument that there is no harm in removing one hair from a beard since it will not stop it being a beard; the argument is superficially convincing until you realise that eventually the beard will indeed disappear, even if it is plucked one hair at a time.
Thus the argument of the beard suggests that there is no difference between those things which occupy opposite ends of a continuum, because there is no definable moment at which one becomes the other: day and night, or childhood and adulthood, for example. This fallacy often turns up in essays that discuss such subjects as the appropriate age for drinking, voting, or driving.