The discoveries of the new science of the sixteenth and seventeenth centuries offered unique challenges to philosophers concerned with answering scepticism or with defending common-sense beliefs. This chapter focuses on how Descartes, Locke, and Berkeley took up those challenges. Descartes’s philosophical project brought to the forefront the tensions embedded in the confrontation between common sense, science, and scepticism. His insistence on raising the strongest sceptical doubts and on answering them with absolute certainty often left common-sense beliefs behind. Confronted with this result, and perhaps also with Descartes’s own failure to answer the sceptic, Locke weakened both the force of his own scepticism and the degree of certainty he demanded in his philosophical views. Moreover, he was often willing to privilege common-sense beliefs over arguments conflicting with them. In these ways, he provided a system which reconciled common sense, science, and scepticism more adequately than Descartes. Berkeley, convinced that his predecessors’ work left the sceptic unscathed, developed views which, he claimed, completed this reconciliation project. But the chapter shows that his views fall short of this goal. The work of these philosophers put in place the foundations upon which later thinkers would tackle this reconciliation challenge.