Free Will Skepticism, General Deterrence, and the “Use” Objection

So, let us look specifically at the features of a legal system that affect the justifiability of general deterrent punishment within that system. General deterrent punishment, as I am prepared to defend it, will have the following features:
—Deterrent threats are announced ahead of time, apply to everyone equally, and are tied to moral reasons that are either obvious (e.g., punishment for murder) or discoverable (e.g., punishment for violating the tax code). The system and its agents use both prudential and moral appeals to, as Hoskins puts it, “persuade citizens not to do that which they have a moral obligation not to do anyway” (Hoskins 2011: 376).
—General deterrence can be implemented so that the sanctions are swift, certain, and parsimonious (Hawken and Kleiman 2009: 9), and I would argue that, in a reasonably just legal system, they should be. It is widely recognized that swiftness and certainty have a substantially greater effect on deterrence than does severity of punishment (Hawken and Kleiman 2009:  9). In addition, a reasonably just legal system should incorporate, in some form, the principle of parsimony, which states that a punishment should be no more severe than necessary in order to achieve its legitimate goals (Tonry 1994: 139).