Language, with its materialistic roots, is an obstacle to discussing non-materialistic phenomena. But there's no disputing that the placebo effect exists, and is the foundation of most medical studies. Likewise, there's no disputing that some very ill people can hang onto life until after a milestone like a graduation or a special holiday, such as Christmas. That phenomenon also defies materialistic explanation.
Jordan Ellenberg explained last year, "But Barry Bonds isn't going to hit 72 home runs for the same reason that there might be no such thing as the placebo effect." The trouble with this is that Bonds ended up hitting 73 homers! (Actually, his argument is sound.) Later, he defended it by saying, "If you bet a hundred bucks at the All-Star Break that Bonds would hit 73 home runs, you made a dumb bet. Now you've got a hundred bucks; it was still a dumb bet."
Update: Andy replies, "But he replies to my argument about the widely accepted placebo effect by citing Barry Bonds' hitting 73 home runs. He doesn't mention, however, that Barry Bonds was apparently taking steroids (I'm told Sports Illustrated suggests this, and Bonds doesn't deny it.)"
False. Bonds admitted using creatine, but has emphatically denied using steriods. See
USA Today or LA Times. He has gained weight in the last couple of years, and is likely to be stronger. Bonds could be lying, but I think that it is just as likely that the media is spreading false rumors about him. The reporters don't like Bonds.