This chapter is organized as follows. In Sect. 2, I summarize the terms and concepts we have covered. In Sect. 3, we revisit the notion of justification, in regard to objects, causal relations and the principle of uniformity. In Sect. 4, we discuss the viability of skeptical realism. Finally, in Sect. 5, we discuss Hume's skepticism in light of his conception of objects, where we briefly touch on Berkelian idealism.