Why did industrial societies develop welfare states in the 20th century?

What are the following roles ?

Ipersonally feel that adolph hitler was a great contributor to american society. "to conquer a nation, you must first disarm it's citizens." sound familiar? hitlers research and studies have even made an impact on our medical research today. walt disney was actually a good friend of hitlers and in fact made an episode of mickey mouse in which donald duck was a nazi. as bias and judgmental as american society is they will never acknowledge the true impact he has had on history as well as society as a whole.