Almost all sentencing decisions contain some reference to mitigating or aggravating factors, yet it is extremely rare to come across a judicial discussion of the rationale or scope of these factors. More to the point, there is very little consideration of mitigation and aggravation from a theoretical perspective. As Ashworth notes, these issues ‘have tended to attract little close examination or theoretical discussion’ (2010: 156). Philosophers have debated some of the issues, but these discussions are, for the most part, limited to arguments about the distinction between mercy and compassion, and their respective relationships with justice. Recently we have also seen efforts by both leading proportionality theorists and their antagonists, the limiting retributivists, to accommodate some sentencing factors in their modes of analysis. While they feel compelled to make this accommodation, neither provides a unified or over-arching theoretical perspective that justifies it. Still, we can learn a lot from their attempts to integrate mitigation and aggravation. The primary lesson is that, from a theoretical perspective, the underlying premises of mitigation and aggravation are elusive.