On the denial of the objectivity of the reality of essences
“As the “new essentialist” Crawford Elder has noted, the denial that essences are in some sense objectively real leads to paradox in any case. For if we say that essences are merely the products of human convention, then that would have to include our essence, the essence of human beings, as well. But that is incoherent. In order to form conventions in the first place, we have to exist as a species, sharing an essence that constitutes us as such; and if our essence thus makes us what we are, we cannot in turn be that which makes our essence what it is.”
Feser, Edward. Aquinas: A beginner’s guide. Oneworld Publications, 2009.