I spent the weekend in bed with the flu.  Sunday morning, on the tail end of it, I popped a few Advil to bring the fever down so I could semi-enjoy Father’s Day. Was I making a mistake?

As I understand it, my body elevates its temperature as a defense mechanism. Evolution has been operating long enough to have a pretty well-calibrated trade-off between the losses of reduced activity from the fever versus the speed and probability of a successful recovery.  Is my intervention distorting away from the optimum?

  1. Arguably I have private information about idiosyncratic conditions and Nature is calibrated only to the average state.  Note that while this hypothesis justifies my use of Advil on Father’s Day, it also implies that I should go short on Advil on other days.
  2. And anyway Nature has given me the infrastructure to condition physiology on my knowledge of immediate environmental conditions.  For example when I know that I am in danger, the body re-allocates resources to help me escape.  What makes this any different?
  3. My objective is probably different.  In Mother Nature’s eyes I am just a vessel from which offspring should spring forth.  She could care less whether I get to practice Pink Floyd’s San Tropez on the piano with my daughters.  So Nature’s revealed preference for activity is necessarily weaker than mine.
  4. But wait, my personal preference for non-reproductive activity is also something that Nature shaped.  So what would explain the wedge?
  5. If I am making the wrong decision by taking Advil it’s not because I have the wrong preferences but because Advil is something Nature never expected.  She has me well-trained when it comes to the fundamentals but she hasn’t had time to design my direct preference for the intermediate good Advil. She must leave it up to me to do the calculation of its implied tradeoffs in terms of the fundamentals. It’s only because of my miscalculation that I am making a mistake.