Abstract

In this paper I make four claims. First, there is an apparent contradiction in Spinoza’s theory of justice. On the one hand, in the Tractatus Theologico-Politicus (1670), he argues that justice is entirely conventional and depends on the ruler’s decision. On the other hand, in the later and unpublished Tractatus Politicus (1677), he claims that man really is a social animal and that we can articulate ideal forms of justice on that basis. Second, to address this apparent inconsistency, we need to look at Spinoza’s use of early modern scholastic metaphysics. Although he rejects scholastic natural law theory, he has adopted another concept from the scholastics that is crucial for his theory: the notion of a ‘being of reason’ (ens rationis). Third, if we consider justice as a kind of being of reason, then we can resolve the apparent contradiction in Spinoza’s approach. I shall argue that concepts of justice are imaginative ‘beings of reason.’ They are products of convention that are not derived from general features of the world but from a particular set of circumstances. Fourth, Spinoza’s social ontology of political concepts like justice has some distinct advantages for contemporary theory. This approach shows how we might be able to provide a framework to integrate politics and natural science without reducing one to the other.