The Great Depression of the 1930s and the Second World War were associated with a rapid growth of unions, and a much larger federal government -- one that assumed responsibility for the overall economy and for protecting particular groups, like the aged and unemployed. How did this influence dominant ideas in the field of industrial relations? How do those ideas correspond with what happened in "the real world" in this period?
(Hint: this question asks you to think like a "materialist"... the question is not how ideas affected the world, but how events in the world made some ideas more appealing or valid or important -- and hence more widely accepted.)