How did Thomas Reid’s philosophy of common sense explain perception?

Thomas Reid’s philosophy of common sense emerged as a direct challenge to the skepticism of David Hume and the subjective idealism of George Berkeley. Reid argued that the "theory of ideas"—which posited that the mind is aware only of its own internal ideas rather than external objects—was the fundamental error leading to philosophical absurdity.12

Instead, Reid proposed that in the act of perception, sensations do not function as mere subjective impressions. Rather, they "suggest" the existence of material objects. According to Reid, these sensations carry with them an inherent belief in the qualities of external objects, a conviction that he maintained belongs to the "common sense and reason of mankind".21

By asserting that perception provides direct access to a material world, Reid sought to ground human knowledge in the shared, intuitive certainties held by both the philosopher and the "day-labourer," thereby rejecting the skeptical conclusions that had previously dominated the discourse.12