And the rats preferred organic.
It is a puzzler that he mentions one small sample of rats
http://norvig.com/experiment-design.html
that doesn't show the same result (indifference to whether or not food is "organic") shown in many human studies he mentions in his article. This kind of study needs a bigger sample size and a great deal more replication.
Here's another problem: how do we know that either human beings or rats prefer what is best for them? Preferences for smells and tastes may have evolutionary origins that are then exploited by adaptations of food organisms in ways that are not beneficial to the eater.
Weird that they chose rats and haven't (that we know of) done a study with humans. After all, it's not as if such a study has any inherent danger.
We were however capable of telling the difference between organic and non-organic chicken tough.
It would be interesting to do a blind taste-test between organic and non-organic produce ... Pepsi Challenge style.