Teach him critical thinking, going to the sources and sound argumentation. That's the best you can do.

It is often a very sobering and healthy experience to follow up what is given as facts in inconventional treatement books.

I applaud you, Amos, for mentioning Semmelweis here. His story is very useful and sometimes only one part is mentioned. He was a good observer and he did trust personal experiences for getting ideas. But he did not trust personal experiences for testing ideas. He is also known for introducing control groups in clinical tests and for using statistics instead of personal single case anecdotes ("my grandfather has smoked all his life and..." "I never had a shot and..."). The part with the necessity of control groups and the usefulness of statistics is often left out when his story is told by alternative medicine proponents. His story is a good case to illustrate the opposition to introducing science and empirical argumentation into medicine when many practitioners still considered it being an art.

But I cannot (that's a lie: want not!) end without a pun on Semmelweis: Would you trust a doctor practicing in Pest?

Wolfgang