There is an apparent tension in Shepherd’s accounts of space and time. Firstly, Shepherd explicitly claims that we know that the space and time of the unperceived world exist because they cause our phenomenal experience of them. Secondly, Shepherd emphasizes that empty space and time do not have the power to effect any change in the world. My proposal is that for Shepherd time has exactly one causal power: to provide for the continued existence of self-same or changing objects. Because (...) Shepherd takes causation to be a relation whereby two objects combine to form a third, their effect, whenever we perceive a continually existing object, since time is a proper part of such objects, our perception of time is caused by time itself. Likewise, space’s causal power is to provide for the possibility of the motion or rest of objects, and so when we perceive objects with space as a proper part, we come into causal contact with space. (shrink)

Shepherd’s philosophy centers on her rejection of Hume’s arguments against the demonstrability of causal principles. According to Shepherd, the causal maxim—everything that begins to exist must have a cause—is demonstratively true. She begins her first major philosophical work with a proof of this maxim. While scholars have complained that the proof seems blatantly circular, a closer look at Shepherd’s texts and their Lockean background dispels this worry. Shepherd’s premises are motivated not by the causal maxim or her theory of causation, (...) but by a metaphysics that distinguishes between substances and affections and by an empirical understanding of a ‘beginning of existence.’. (shrink)

Mary Shepherd assigns reason a central role in her philosophical system, and so to understand that system we must understand her conception of reason. Does she, like Hume, take reason to be a mere matter of factual process that operates over independently contentful representations? Does she, like Descartes, take it to be a process that is intended to track the rational relations among such representations? Or does she, like Kant, take reason to be a structural feature of representations without which (...) they would not have content at all? I argue that Shepherd's understanding of reason is broadly Kantian. Reason is a causal process whereby non-representational sensible qualities are combined in order to form representations of objects as loci of causal powers. These representations represent their objects as the external, continuously and independently existing, causes of the sensible qualities from which they have been constructed, and also as having causal powers to combine with other objects to have other effects. These representations are not only the result of a process of reasoning, but are also constituted by the rational relations into which reason puts them. Reason is both the causal process that forms such representations, and the structure of those representations themselves. (shrink)