The Book of Why: The New Science of Cause and Effect

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.

you cannot answer a question on rung two of the Ladder of Causation using only data collected from rung one.

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

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.

If the message went from parent to child, the child would update its beliefs using conditional probabilities, like the ones we saw in the teahouse example. If the message went from child to parent, the parent would update its beliefs by multiplying them by a likelihood ratio, as in the mammogram example.

While rung one deals with the seen world, and rung two deals with a brave new world that is seeable, rung three deals with a world that cannot be seen (because it contradicts what is seen).

selectively break the rules of logic.

Philip was the first economist to make use of his son’s invention of path diagrams.

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