See my blog on confrontational training techniques. My point is that confrontation (ok, punishment) based techniques can be very effective in the hands of highly qualified trainers, with dogs of particular temperament and upbringing (like, say, police and military dogs!). But in the hands of the inexperienced trainer (like, say, most pet dog owners) with dogs of inappropriate temperament and upbringing, punishment techniques have a strong potential for producing a lot of negative side-effects like anxiety. Positive reinforcement techniques, while one can argue the relative effectiveness in the hands of the unskilled, are very unlikely do damage, to make things worse. Hence I am very opposed to any suggestion that pet dog owners should use punishment or confrontational techniques with a high degree of training and assessment of the dog. This is different than saying that no one should ever train any dog with punishment techniques.

Hope this helps! If you have a specific, or additional, question, let me know!

Cheers,
Jim Ha