This paper presents a puzzle or antinomy about the role of properties in causation. In theories of properties, a distinction is often made between determinable properties, like red, and their determimztes, like scarlet (see Armstrong 1978, volume II). Sometimes determinable properties are cited in causal explanations, as when we say that someone stopped at the traffic light because it was red. If we accept that properties can be among the relata of causation, then it can be argued that there are good reasons for allowing that some of these are determinable properties. On the other hand, there are strong arguments in the metaphysics of properties to treat properties as sparse in David Lewis’s (1983) sense. But then it seems that we only need to believe in the most determinate properties: particular shades of colour, specific masses, lengths and so on. And if we also agree with Lewis that sparse properties are ‘the ones relevant to causal powers’ (1983: 13) it seems we must conclude that if properties are relevant to causation at all, then all of these are determinate properties. I call this ‘the antinomy of determinable causation’. On the one hand, we have a good argument for the claim that determinable properties can be causes, if any properties are. I call this the Thesis. But on the other hand, we have a good argument for the claim that only the most determinate properties can be causes, if any properties Work on this paper was made possible by a fellowship at the Collegium Budapest, Hungary, and by support from the AHRB’s Research Leave Scheme. Thanks to participants at the 2004 NAMICONA special science causation workshop in Aarhus, to participants at a workshop on mental causation at Macquarie University in 2004, and to audiences at the Universities of Edinburgh, the LSE and Warwick. Special thanks to Jordi Fernandez, Jakob Howhy, and (especially) Jesper Kallestrup for their helpful written comments.