Thanks to paul in the comments below here's a link to the Maudsley debate on antidepressant efficacy, 'This House Believes Antidepressants are no Better than Placebo', featuring Irving Kirsch, Joanna Moncrief (for), Guy Goodwin, and Lewis Wolpert (against).
Interestingly Kirsch turns the question around to argue that there is no evidence that antidepressants are clinically significantly better than placebo (as you may be aware, I've addressed the Kirsch et al PLoS paper before).
Both Kirsch and Moncrief make some good points, but I was struck by Moncrief's claim that because we don't know that antidepressants act specifically against 'the' biological cause of depression, and in fact may have rather more non-specific effects that help to ameliorate the symptoms of depression, we therefore should not use them.* She goes on to argue a completely contradictory point at the end of her speech to claim that because antidepressants are (according to her) no better than placebo they are therefore harmful because they are not inert. Yet her argument that antidepressants are not superior to placebo hinges on the claim that their apparent superority hinges on their active side effects in clinical trials.
Goodwin and Wolpert make some fairly pedestrian counterarguments, some fallacious, largely anecdotal in Wolpert's case. The comments from the floor included some 'service users' ranting and anti-psychiatry, which is quite common at psychiatric talks.
* I've long been drawn to the idea (can't remember who first proposed it) that serotonergic antidepressants flatten emotional responses and noradrenergic antidepressants are activating. But both these effects would seem to me to be very useful in helping to relieve symptoms of depression and facilitate true recovery. Comments from the floor point out that in the rest of medicine we don't abandon treatments proven to work in clinical trials because we don't know their mechanism of action. In fact, it is pretty hard to see what Moncrief would advocate to treat depression instead of antidepressants, surely we can't know that physical exercise or CBT are definitely treating the underlying physical abnormality?