One who studies crime, criminals, and criminal behavior is called a?

Kennedy implies that starting a nuclear war would be insane. why?

Trench warfare began after germany failed in its initial plan to seize france and bring a quick end to the war. negotiate a temporary truce with the allied forces. attack the allies by sea with its powerful navy. storm across the eastern front to attack russia.

Why would employers want there to be large numbers of unemployed workers around?