Some of these particular claims could be 'debunked', I suppose, to the extent that they are really more in this line of aphorisms than fully developed philosophical positions. For instance °2 is merely a moral assertion, not a moral argument, and °4 seems to be a sincerity challenge. These argumentation tactics are both useful, with their own particular rhetorical power, but they can be dismissed by someone pursuing a more intellectual/rational form of argumentation. But the underlying thought — that retributivism is pointless, ineffective, and often counterproductive — is far more difficult to refute.
One of the standard principles of justice is equilibration: that the point of a justice system is to maintain and restore balance between equal citizens. This generally hinges on two age-old concepts: restoration and penance. In other words, if A steals a thousand dollars from B, the goal of a justice system would be:
- To restore the stolen funds to A, to the extent feasible, and
- To subject B to some penance for the act, in order to restore B's credibility and discourage future repetitions of the offense by him or others (this might be anything from a simple apology, to damages, or to loss of privileges and liberties)
There are two problems with the implementation of these concepts. First, many outcomes are not directly restorable: e.g., death, illness, disfigurement, or mental/physical torment, etc take something from people that cannot be given back to them, and are difficult to evaluate in simple economic terms. Second, penance generally implies cooperation from the guilty party, and a desire on their part to regain their status in the social contract. These problems are why courts in modern law systems have such strict rules about evidence and testimony; they are trying to ensure rational, reasonable outcomes in a context fraught with subjective and emotionally charged opinions.
The difficulty with retribution as a judicial concept is that it is inherently non-restorative, and does it qualify as a form of penance. Retribution (arguably by definition) doesn't try to restore what the victim lost, and (arguably by definition) goes beyond what any guilty party might reasonably agree to as penance. Retribution is thus alienating, not reintegrative. It is something inflicted on the guilty party to demonstrate dominance and power, not something asked of the guilty party as an act of atonement. This intuition is what lies behind claims °1, °3, and °5. If a crime is an act of unjust power, then a repetition of the act by the state or victim against the criminal is also an act of unjust power. Not to put too fine a point on it, but if a rapist is raped in retribution for his crime by the brother of his victim, is that rapist now a victim in his own right, whose friends and family might seek retribution against the brother of the original victim by raping him in turn? In Kantian terms, retribution is something we might feel righteous about inflicting on others, but not something we would willingly agree that others have a right to inflict back on us and ours. That brings its morality into question.
Retribution and justice are both social concepts, but they are social concepts of different sorts. Justice aims for balance: for a wrong to be righted and a perpetrator to express remorse, so that the fabric of social life can return to something congenial to all. By contrast, retribution aims to restore the victim at the expense of the perpetrator, by repeating perpetrators' crimes against them. While I can understand the visceral, selfish appeal of it, it doesn't stand up to philosophical investigation, and has no real place in rational law.