 This argument suffers from well-known problems. For instance, since laboring is an activity, the idea of mixing it with an object seems at best a metaphor for something else. But in that case, the argument is incomplete: we still need to know what really grounds property rights (Waldron 1988). More importantly, it simply is not true that mixing something owned with something unowned is sufficient for appropriation. As Nozick pointed out, if I pour a can of tomato juice that I own into the unowned ocean, I lose my tomato juice—I do not gain an ocean (Nozick 1974, pp. 174–5). Third, if labor-mixing really were sufficient for generating claims in objects, why should this be restricted to unowned goods? Why not say that mixing my labor with something already owned generates a claim of coownership (Thomson 1990, pp. 326–327)?