Lea Aurelia Schroeder

According to the standard Geometry First view, the geometric properties of elemental particles in the Timaean cosmos determine and explain their physical properties and causal powers. This chapter identifies several problems for the Geometry First view: first, physical properties of particular elemental particles may change even when their geometric properties do not; second, there is no function from specific geometric properties of elemental particles to specific causal powers to affect identical or different patients; and finally, the same geometric property may be central in the explanation of one causal power, but explanatorily peripheral in the case of another, similar causal power. Despite the context-sensitive role of geometric properties, there is nevertheless order in the relations between different kinds of elemental properties. A modified account of the relation between geometric properties and causal powers can capture these complex relations in part by distinguishing between essential and variable geometric properties. The notion of (merely) partial, non-vacuous grounding can help articulate the role of specific geometric properties in determining specific causal powers even and especially when these geometric properties are explanatorily peripheral.

In the Theaetetus, Plato seems to rule out the possibility of perceiving ordinary objects (Tht. 184–87), only to rely on it shortly afterward (Tht.191–96). Unlike existing interpretations, this paper develops a unified conception of perception that resolves not only this apparent inconsistency, but also a substantive puzzle about how to understand object perception and its relation to perception of special sensibles. This conception is part of a surprisingly rich account of perceptual experience in the Theaetetus that illuminates the contribution of perception to cognition.

Scholarship on Plato's Timaeus has paid relatively little attention to Tim. 77a–81, a seemingly disjointed passage on topics including plants, respiration, blood circulation, and musical sounds. Despite this comparative neglect, commentators both ancient and modern have levelled a number of serious charges against Timaeus' remarks in the passage, questioning the coherence and explanatory power of what they take to be a theory of respiration. In this paper, I argue that the project of 77a–81e is not to sketch theories of respiration, circulation, and digestion, but to explain how the human body is maintained in light of and despite constant environmental depletion. Further, I argue that in order to understand this account of “the replenishing system,” we need to understand Timaeus' striking analogy of the fish trap or nassa. Commentators have generally focused directly on the workings of the bodily construction that Timaeus likens to a fish trap, but without considering how we should understand the analogy qua analogy. I develop a functional reading of the analogy that yields a coherent account of the replenishing system on which previous criticisms of Timaeus' remarks on respiration do not arise. Aside from lending greater unity to the passage, both internally and within its immediate context in the dialogue, this account of the replenishing system contributes to our understanding of Timaeus' reason-and-necessity explanatory framework as applied to the human body and has noteworthy implications for specific explanatory principles, in particular like-to-like motion and circular thrust.

The principles governing elemental composition, variation, and change in Plato’s Timaeus appear to be incompatible, which has led commentators to prioritize some of the principles to the exclusion of others. Call this seeming incompatibility the problem of isomorphic variants. In this paper, I develop the theory of proportionate atomism as a solution to this problem. Proportionate atomism retains the advantages of rival interpretations but allows the principles of material composition, variation, and change to combine into an internally coherent and explanatorily powerful atomic physics.