[ghaff]

One of the things that I didn't quite get when I started taking organic chemistry was that I really couldn't figure out (didn't have enough background knowledge) why many reactions happened the way they did and that I just had to memorize things.

(Accounting is the same way though for very different reasons. You could justify recording some transactions in about 5 different ways--but FASB says only a particular one is OK.)

[dnautics]

At the grad level students get really good at rationalizing and predicting reactions. We did bimonthly exercise called mechanism club where someone would pick some chemical reactions from the literature and basically volunteers would come up to the chalkboard and push electrons till the reaction was complete.