Impure concepts and non-qualitative properties

Some properties such as having a beard and being a philosopher are intuitively qualitative, while other properties such as being identical to Plato and being a student of Socrates are intuitively non-qualitative. It is often assumed that, necessarily, a property is qualitative if and only if it can be designated descriptively without the aid of directly referential devices. I argue that this linguistic thesis fails in both directions: there might be non-qualitative properties that can be designated descriptively, and there appear to be qualitative properties that can only be designated directly. I conclude that while the linguistic thesis is ultimately untenable as stated, it can be plausibly recast as a thesis about our concepts rather than the properties they designate.