@failures art,
Art, we could do as you suggest and post links to all sorts of "experts" who supposed our positions, but to what end?
I suspect we can produce an identical number of links, none of which will be so compelling that either of us will concede the other's point.
Here's what we know: Numerous serious people (including Leon Panetta) have concluded that enhanced interrogation methods provided important actionable intelligence.
The argument that the same intelligence could have been obtained with less invasive methods can never be proved.
I don't know if you own a house, but if you do, let's imagine it is invaded by vermin: mice, squirrels, raccoons, etc. There are all sorts of recommended ways to rid your home of such pests, but none of them work perfectly. Let's say in your particular case however, your last resort, poison traps, does the trick, and rids you of the vermin.
Now comes an animal lover who insists that live traps would have worked as
well. As a matter of fact, you tried live traps and it didn't work, but that's not to say that additional attempts would not have worked. In any case you know the poison traps did work.
The next time vermin invade your house are you going to very possibly waste
time with live traps or are you going straight to poison?
The live trap advocate is bound to tell you that you really don't know if you could have gotten rid of the pests without killing them, and he probably would be right.
Killing vermin sucks, but so does a vermin infestation.