Logic has nothing to do with it. Emotions are emotions, and you're a person. People can't just be expected to pretend them away or turn them off. Even if emotions might make people do stupid, irrational things sometimes. They're still important.

[And boy does Edward know about emotions leading to bad decisions and terrible mistakes.

He will calm down slightly when his attention turns to alchemy.]

The different techniques and theories. How certain categories of transmutations should be performed -- the various necessary components and elements. Different ideas of transmutation circles. Alchemy has all sorts of practical applications. Combat, construction... some people can even use it for healing.