In this paper I offer a reconstruction of one of Husserl’s various anti-materialist arguments. Husserl hints at this argument in Ideas II & III where he exposes essential differences between mental and material reality (Realität). At its core, Husserl claims that mental entities by their very essence can never be in the same qualitative condition at different times. By sharp contrast, for purely material or physical entities such a cyclical development is not essentially excluded. Accordingly, I will speak of Husserl’s argument from irreversibility. I argue that this argument is modal in nature, and that it can be used to make a case against materialism based on the necessary supervenience of the mental on the physical. My primary goal is to elucidate this argument, and to offer a logical reconstruction using basic modal logic and contemporary notions of supervenience. I conclude that Husserl’s argument is formally valid, and that it can even held to be sound, although the premise regarding the necessary irreversibility of the mental requires further clarification.
In the Physics, Aristotle says that there is no change associated with the category of relatives. In this paper, I examine a widespread but neglected strategy that medieval thinkers use to understand Aristotle’s claim. According to this strategy, which I label initial presence, if there is no change in the category of relatives, it is because the relation-properties are already present in their subject as soon as the properties on which relation-properties are founded exist. Appreciating the importance of this strategy is crucial not only for understanding medieval theories of relation but also for assessing the credibility of arguments used in the secondary literature to interpret medieval texts, in particular a well-known passage from Thomas Aquinas’s commentary on the Physics.