Health, Science, and Hume

Dean Esmay posted an Open Challenge last night:

Can anyone point me to a peer-reviewed study which shows a reduced mortality rate from eating a low-fat or low-cholesterol diet?

I started to weigh in at the time but thought I smelled a trap, so I posted the first comment in the thread:

What are your standards for proof here?

The question hasn’t been directly answered but applying inductive reasoning based on the exchange so far, I gather that the standard is somewhat higher than that required to demonstrate that smoking two packs of cigarettes a day will decrease one’s life expectancy.

Human physiology is amazingly complicated. I’m not sure we’ll ever get to the point where we can identify specific behavioral patterns and make direct causal leaps, beyond such comparatively uninteresting matters as that ingesting some large quantity of a poison will be lethal. There are just too many other variables involved–genetics, overall physical condition, lifestyle factors such as stress and exercise, etc. The effects of eating a particular diet are certainly going to be different for different people, in not wholly predictable ways.

David Hume long ago cautioned us about the impossiblity of being absolutely certain about our expectations of the future. But he would allow that we can make prudent guesses about the future based on past experience.

On the main, it’s probably a bad idea to routinely eat a diet that’s very high in saturated fat on a regular basis, just as smoking two packs of cigarettes a day is unwise. There are certainly people that live to be a ripe old age despite doing one or both of those things. That doesn’t make it a good idea.

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James Joyner
About James Joyner
James Joyner is Professor and Department Head of Security Studies at Marine Corps University's Command and Staff College. He's a former Army officer and Desert Storm veteran. Views expressed here are his own. Follow James on Twitter @DrJJoyner.