  In this paper we compare two different notions of 'power', both of which
attempt to provide a realist understanding of quantum mechanics grounded on the
potential mode of existence. For this propose we will begin by introducing two
different notions of potentiality present already within Aristotelian
metaphysics, namely, irrational potentiality and rational potentiality. After
discussing the role played by potentiality within classical and quantum
mechanics, we will address the notion of causal power which is directly related
to irrational potentiality and has been adopted by many interpretations of QM.
We will then present the notion of immanent power which relates to rational
potentiality and argue that this new concept presents important advantages
regarding the possibilities it provides for understanding in a novel manner the
theory of quanta. We end our paper with a comparison between both notions of
'power', stressing some radical differences between them.
