Also remember, placebos aren't just for patients, they are for clinicians, too. Placebos play a central role in the pivotal concept in modern day trials, randomization. I'm sure you realize there needs to be *some* sort of control group. In double-blind trials, the doctors won't know what the patient has been given, placebo or treatment, so biases are reduced compared to if they did know (who gets into the trial, for instance?). There are many biases, including subconscious ones, that can come out when the observer (doctor) knows the assigned treatment.