Low skills can explain low wages but not unemployment. The history of blacks provides concrete evidence. A person is qualified or unqualified only in a relative sense – that is, relative to some wage. For example, a carpenter who is qualified, and hence employable, at a wage of $20 per hour, may be unqualified, and hence unemployable, at $35 per hour. This principle applies to everything. A Sears suit is “unqualified” to sell for the same price as a hand-tailored Pierre Cardin suit.
By “The history of blacks provides concrete evidence,” Walter refers to the overwhelming evidence that shows that, when governments do not obstruct labor-market transactions with the likes of minimum-wage statutes, equal-pay-for-equal-work requirements, and occupational-licensing restrictions, blacks (and other minorities) have no more trouble finding employment than do whites and other groups of people. Some of this evidence is offered in the book from which the above quotation is drawn.