The Unbearable Weight of Simplicity in Theory Choice

When philosophers do not have a way out for choosing between the account they defend or a competing one, they usually appeal to theoretical virtues, such as simplicity, unity, fruitfulness, explanatory power, and so on. In this paper, my aim is to question the status of simplicity as a criterion for theory choice. My main arguments are that, first, it is hard to determine an objective metrics for evaluating simplicity, and second, we have no way to decide which one we should prioritize: whether the ontological or the ideological variant of this theoretical virtue. In order to defend this stance, I will present the defenses of both ontological and ideological simplicity and then criticize each of them. I will also point out that the usual appeal metaphysicians make to scientific practice is not enough, given that the role of simplicity in science is not so clear and that philosophy in general has a very distinct nature as an endeavor. In the end, I will sketch a metaphilosophical pessimistic conclusion according to which not just metaphysics, but much of philosophy, is maybe doomed to be an endless effort of inconclusive arguments, since most of philosophical explanations appeal to theoretical virtues as a decisive factor in their disputes.