 The Existence Question: Some are skeptical that there is a real distinction between accidental and essential properties. Quine (1953 [1961], 1960) argued that whether or not a property is essential to an object depends on how we refer to it. More recently, Sidelle (1989) has provided an anti-realist view of essences. Mackie (2006) and Ásta (2008, 2010, 2013) have offered a critique of realist approaches to essences. Further criticism of essences comes from recent philosophy of science. Particularly, several philosophers of biology have criticized biological essentialism (e.g., Ereshefsky 2010; Leslie 2013; Okasha 2002; for discussion: Devitt 2021; Dumsday 2012).