The monotonicity of essence

Kit Fine’s logic of essence and his reduction of modality crucially rely on a principle called the ‘monotonicity of essence’. This principle says that for all pluralities, xx and yy , if some xx belong to some yy , then if it is essential to xx that p, it is also essential to yy that p . I argue that on the constitutive notion of essence, this principle is false. In particular, I show that this principle is false because it says that some propositions are essential to yy even though those propositions are only about some of its members. I then consider modifications to the principle appealing to consequential essence and argue that such a modification is inconsistent with a central desideratum of Fine’s approach to metaphysics, what I call his neutrality condition.