This video explains the philosophical concept of essentialism, which posits that objects possess real essences or natures independent of human perception or convention. The speaker presents three main arguments in favor of essentialism: the "no-miracles argument," arguments derived from scientific practice and results, and the incoherence of pure conventionalism. The video also clarifies what essentialism is not, differentiating it from existentialism, Platonism, or mystical interpretations.