Quantum Mechanics, Chance and Modality

The thesis of this article is simple: even if it is accepted that quantum mechanics is a fundamentally probabilistic theory, this provides us with no special reason to believe in “chances” in the sense of objectively existing factors that are responsible for the relative frequencies we encounter in experiments. More in general, quantum mechanics gives us no special reason to believe in the actual existence of modalities. We may intuitively be inclined to believe in chances as a kind of causes, just as in classical mechanics we are inclined to think of forces as causal powers that produce accelerations. It might even be the case that intuitions of this kind can be developed into a coherent metaphysical scheme (something which has yet to be done, I think). But as I shall argue, a sober Humean perspective on quantum mechanics is certainly possible as well, and has much to recommend it. In short, the thesis of the present paper is that for a Humean, quantum mechanics introduces no reasons to abandon his position.