According to the thesis of powerism, our world is pervaded by causal powers which are metaphysically basic. The aim of this paper is to defend the existence of the self, defined as a substantial entity, and its mental powers. This claim, which may seem a bold one, should not be deemed as inconsistent with scientific evidence. In fact, this approach does not ignore empirical knowledge, but is not bound only to it in order to understand entities, properties, and the relationship (...) between them. Aristotelian powerism may show that the self, as the subject of one’s mental acts, is a substance that has an essential nature. Firstly, we shall analyze the immediate evidence we have in support of the existence of the self as a substantial entity. We will show that the self is a substance because it possesses an essential character, i.e. an individual essence. We will take into account the Aristotelian perspective of substance, trying to show how the presence of a necessary property that makes every subject identical to itself and the phenomenal features of one’s private experience point to the existence of a substantial entity that corresponds to the self. Secondly, we will try to justify the adoption of a metaphysical theory of causation based on powers, analyzing it in comparison with the main competing theories, namely hypotheticalism and nomism. Then, we shall proceed to show the causal properties of the substance in question, namely the mental powers. In fact, thirdly, we will embrace the thesis of powerism by defending the existence of a set of mental powers that should be attributed to the self. We will describe the main features of mental powers and we will show that they are conceivable as the pure intentional acts we perform by directing an intentional state towards an intentional object. In this way we show how a classic problem of philosophy of mind, relevant to science as well, can be addressed in an original way by a metaphysical approach involving powers. (shrink)