What are the motifs in A Treatise of Human Nature by David Hume?

Skeptics are a recurring idea. Another interpretative controversy in Hume studies is over whether Hume was a true radical skeptic. A skeptic in this context is someone who denies a wide range of common sense truths. Hume will initially appear to be a radical skeptic, and shockingly so. He denies all of the following common sense claims: that humans have knowledge of reality as it really is, that all contingent events have causes, that causation is a bona fide feature of reality, that emotions have a rational component, that humans make free choices, that humans have a self and a soul, that morality is at least partly rooted in reason, that justice is natural to humans, and that morality is ultimately about something more than pleasure and pain. How then could Hume be anything else but one of history's greatest skeptics?