This month's issue has an excellent article by Amy Dahl in the ASK THE PRO feature. She discusses behaviorism as it applies to retriever training. She includes positive reinforcement as well as punishment. It seems that she uses both in her training. (Most of us do.) She also discusses shaping of behaviors. She even mentions Premack's principle and the use of the breaking cord (slip cord---a tool that seems to be out of fashion).
This is an excellent read. She says a lot in a two page article. And she does criticize, very gently, the haranguers who don't deliver the message of positive reinforcement too well.
If you get the magazine check out the article.