For Stebbing, common sense was the only reasonable starting point for any (initial) inquiry. We can start nowhere in our exploration of what the world is like and what is true than with our commonsense beliefs. For this reason, getting a precise picture of what ‘common sense’ means for Stebbing, and how we can deploy the concept, is incredibly important. This chapter sketches a more robust notion of what Stebbing takes common sense to be, which includes at least four traits: common sense is public, needs no justification, and is the beginning, but not end, of both science and metaphysics. It then considers an extended example of Stebbing’s treatment of the commonsense notion of ‘number’, showing how the four identified traits play out in that case. The chapter concludes by showing how her views differ from Reid’s in robust and substantive ways. This adds further confirmation to the claims in Coliva (British Journal for the History of Philosophy, 29, 914–934, 2021) and Janssen-Lauret (Journal for the History of Analytical Philosophy, 5(2), 6–17, 2017) that Stebbing’s philosophical position is rich, interesting and novel.