This article turns to Spinoza to shed new light on what Roberto Esposito, among others, has diagnosed as modernity’s "immunitary dialectic," whereby juridical-political measures taken to safeguard or immunize individual and collective life threaten to debase and even destroy the life in question. I argue that Spinoza’s treatment of the "freedom to philosophize" offers a window onto the plural politics of immunity – that is, the institutions and practices that convert the power to preserve life into tendentially dominative and emancipatory forms.