On many interpretations of Spinoza’s political philosophy, democracy emerges as his ideal type of government. But a type of government can be ideal and yet it can be unwise to implement it if certain background conditions obtain. For example, a dominion’s people can be too ‘wretched by the conditions of slavery’ to rule themselves. This begs the following question. Do Spinoza’s arguments for democracy entail that all political bodies should be democracies at all times (the received view), or do they (...) merely entail that we should only have a democracy when the right sort of background conditions are in place (the challenging view)? This paper argues that a new interpretation of one of the four versions of the rationality argument for democracy as it features in the Tractatus entails that the received view is correct. The paper also explains away part of the appeal of the challenging view by arguing that none of the other versions of the rationality argument supports the received view. It closes by arguing that a slightly modernised version of the rationality argument can be important for contemporary political philosophy. (shrink)