You've clearly spent some time looking up links to support your cause, so it's unfortunate that you've cherry picked only the ones that support your beliefs. Here are some others that say the opposite.
Note also that 2 of the 4 links you provided are comparing certainty-of-punishment vs harshness-of-punishment. This is a false dichotomy. There's no reason you can't have both. Having harsh punishment doesn't reduce the certainty of punishment in any way.
Is there a lot of contentious debate on this topic, and a lack of consensus on this topic? Of course. But given the lack of clear answers, I'd much rather err on the side of preventing victimization.
> But given the lack of clear answers, I'd much rather err on the side of preventing victimization.
In America, we have historically low crime rates and historically low violent crime rates. Simultaneously, we have an insane crisis of prison overpopulation that leads into multi-generational cycles of poverty.
I too would rather err on the side of preventing victimization.
Right now, from where I sit, over-criminalization is a bigger problem than violent crime.
"Sentence Enhancements Reduce Crime"
http://www.nber.org/digest/oct98/w6484.html
"Longer prison sentences deter re-offending, study shows"
http://www.telegraph.co.uk/news/uknews/law-and-order/8504923...
Longer sentences deter crime up to a point
http://www.economist.com/blogs/freeexchange/2016/03/criminal...
"Longer prison terms really do cut crime, study shows"
https://www.theguardian.com/law/2012/jul/07/longer-prison-se...
"the average add-on gun law results in a roughly 5 percent decline in gun robberies within the first three years"
https://www.law.upenn.edu/cf/faculty/dabrams/workingpapers/D...
Note also that 2 of the 4 links you provided are comparing certainty-of-punishment vs harshness-of-punishment. This is a false dichotomy. There's no reason you can't have both. Having harsh punishment doesn't reduce the certainty of punishment in any way.
Is there a lot of contentious debate on this topic, and a lack of consensus on this topic? Of course. But given the lack of clear answers, I'd much rather err on the side of preventing victimization.