Maybe his Midwestern upbringing and the tiny college he went to encouraged his self-reliance and taught him that the surest kind of knowledge is what you construct yourself.

must master at least three distinct levels of cognitive ability: seeing, doing, and imagining.

Counterfactual learners, on the top rung, can imagine worlds that do not exist and infer reasons for observed phenomena.

But what are the messages? This took me quite a few months to figure out. I finally realized that the messages were conditional probabilities in one direction and likelihood ratios in the other.

The recognition that causation is not reducible to probabilities has been very hard-won,

of the data increases, leaving a single objective conclusion in the end.

having such laws permits us to violate them selectively so as to create worlds

However, randomization does have one great advantage: it severs every incoming link to the randomized variable, including the ones we don’t know about or cannot measure (e.g., “Other” factors in Figures 4.4 to 4.6).

A Bayesian network is literally nothing more than a compact representation of a huge probability table.