 Mary Shepherd (1777–1847) is the author of several works advocating a systematic metaphysics and theory of knowledge which were highly regarded by her contemporaries. Born and raised a short distance from Edinburgh and well versed in the intellectual life of the city, she urges a philosophy adamantly opposed to main tenets of the Scottish school. She finds them unable to sustain scientific inquiry, everyday practical reasoning, and belief in an almighty deity. Her aim is to replace them with a metaphysics consisting of existential beliefs held for good reasons. An analysis of causality is primary in her theory. She contends that the relation between cause and effect is one of efficacy, necessity, and simultaneity. The first of her two books, Essay upon the Relation of Cause and Effect (Shepherd 1824; abbreviated ERCE), is chiefly concerned with deriving and developing this doctrine while pointing to errors in the reasoning of Hume and his followers on this subject. Her second volume (Shepherd 1827a) has two parts. The first is a long treatise Essay on the Academical or Skeptical Philosophy (abbreviated EASP) which uses causal reasoning to explain the origin and justification of existential beliefs with regard to the external world, ourselves, and God. The second consists of shorter essays said to be illustrative of doctrines contained in the first part of this volume and the earlier one published under her name. Her theory of knowledge is neither rationalist nor empiricist; it takes all knowledge to unify passively received sensations with principles drawn from the faculty of reason, so that knowledge of all sorts is at once felt and represented discursively. In this respect, her position is more like that of Kant than like those of her other early modern predecessors. But her metaphysics and theory of the justification of existential beliefs are distinctive of her philosophical system. 