A stupid question:
In Nielsen's first "problem for the author", he writes,
An alternate, equivalent approach to defining causal models is as follows ...
But I can't tell the difference between the "alternate" approach and the original one. For example, Nielsen says that the alternate approach "introduces the overhead of dealing with the augmented graph". Wasn't this already necessary in the original approach?
Okay, suppose you have a two node system. One node is whether someone smokes, one node is whether there's tar in their lungs. The smoking node has a causal influence on the tar node, but there's also a random factor. Say if someone smokes they'll have tar in their lungs, otherwise there's only a 5% chance they do. This is only two nodes. To express this in the alternate approach, the tar node needs to be a deterministic function of other nodes, and an extra random node is required for this. It could be a "polluted atmosphere" node, value "ye...
Michael Nielsen has posted a long essay explaining his understanding of the Pearlean causal DAG model. I don't understand more than half, but that's much more than I got out of a few other papers. Strongly recommended for anyone interested in the topic.