Dear Economist,

My son has become addicted to economics. The more diligently I confiscate his economics books, the more he steals from my purse. I'm determined that he should grow up to be normal, frequenting the pub like everyone else. What should I do?

-- Stymied in Stratford

Dear Stymied,

You tell a sad story, but one that can be analysed using the theory of rational addiction developed by economists such as George Stigler, Gary Becker and Kevin Murphy.

Addictive goods and activities have some interesting properties. First, addictiveness itself: the pleasure produced by consumption is higher if past consumption has been high. In other words, the more heroin, alcohol or neoclassical growth theory the addict has consumed, the less bearable it will be to abstain now.

Second, past consumption will also have a direct bearing on the addict's happiness. Typically, we think of negative addictions: past consumption of crack makes for a miserable junkie today. But positive addictions are possible too. A progressive addiction to yoga or to reading may make for a happier and happier person. I am addicted to my wife - so far, with unambiguously positive results.

Your son's addiction is probably a positive one, which will make him ever more fulfilled. But even if it is a negative addiction, you must remember that rational addicts are utility maximisers. He may have been driven to addiction by circumstances - a desire to escape an over-controlling parent, for instance - but trying to frustrate his desires will make him more miserable.

What could be more heart-rending than to see a true passion for economics crushed by an economically illiterate parent?

I must urge you to stop your ill-advised policy of prohibition and adopt the more enlightened approach of laissez-faire.

This week's Economist is Tim Harford, www.timharford.com. Send questions to: economist@ft.com