I would argue that non-white neighborhoods are policed heavier, and as a consequence they "catch more criminals" in those neighborhoods.
But the morgue has a pretty close to 100% set of data on murder victims. It's hard to argue that those are caused by catching more criminals. (And in fact, murders in high-crime neighborhoods are less likely to be solved. If anything, murders are caused by this failure to catch first-time murderers, before their second go. Their victims are also, usually, residents of the same bad neighborhoods.)
Once you are talking about solving a murder, clearly that one was not prevented. It may draw detectives to the neighborhood looking for clues. It's pretty hard to argue that the causality runs from these detectives to the murder though.
No, I'm not, and I didn't say anything remotely suggesting that.
I agree that being locked up once surely makes going straight harder (because employers are wary) and going crooked easier (as you now have more contacts). This is a real problem we should try to address. But I'm not convinced that looking the other way at violent crime is at all the right approach.
However, there is no way this is the main causal link between policing & crime. It's like suggesting that the birth rate is caused by hiring more schoolteachers in a neighborhood, ignoring the obvious fact that the city hires them (largely) based on observed need.
It's not just a question of "going straight" - most "criminals" aren't professionals who have to make a discrete decision to stop their hypothetical "life of crime." Even if we ignore the types of "crime" that essentially involve engaging in normal behavior and being unlucky enough to get caught (ex. jaywalking, driving after having a few drinks at happy hour, or smoking marijuana) and look at violent crime, you'll find that a significant percentage of that is the result of social/psychological/economic instability and is directed at those within the social network of the individual involved. Many of these crimes are so-called "crimes of passion" or the result of some form of mental illness - in neither case is an individual likely to stop, think carefully, and rationally conclude that committing a violent crime is in their best interest.
You can lock someone like that up to prevent them from repeating actions that harm those around them, but you can only do that retroactively (which does little in material terms for victims). Given that less than half of crimes committed each year (including violent crime) are even reported to the police, and that a majority of crimes which are reported to the police aren't solved, it seems much more proactive to work towards a solution that prevents people from ending up in the type of situation that produces criminals to begin with. Proactive policing can easily be at odds with that goal if it throws petty criminals into unmanageable situations that preclude them from having a "normal" life. We can't forget that poverty itself is hugely correlated with crime.
> But I'm not convinced that looking the other way at violent crime is at all the right approach.
I don't think anyone is proposing "looking the other way" with regard to violent crime. I'm certainly not. I think it would be beneficial to make prisons more humane, in that it would increase the chance of rehabilitating them, but I don't think enacting some real-life version of "The Purge" is a reasonable course of action.
> However, there is no way this is the main causal link between policing & crime.
Oh, I definitely agree. My intention was to point out an edge case, not imply that police are the main source of crime.
If they are concerned about the police arrest stats or racism biasing the data set, they could keep the input to something hard to interfere with, like where murders occur or where crimes are reported by the public, rather than where arrests occur.
My opinion is that predictive policing does need regulation, but banning it entirely, to me, seems like an overreaction that will over time result in much less effective use of police resources. I suppose time will tell.
Also, depending on what you consider a violent crime, lack of reporting / local police department's doing something about the report can very well have skew crime rates in certain areas.