Was Fairness in IR Discussed by Cooper and Robertson in the 1970's?

I discuss fairness in Information Retrieval (IR) through the eyes of Cooper and Robertson's probability ranking principle. I argue that unfair rankings may arise from blindly applying the principle without checking whether its preconditions are met. Following this argument, unfair rankings originate from the application of learning-to-rank approaches in cases where they should not be applied according to the probability ranking principle. I use two examples to show that fairer rankings may also be more relevant than rankings that are based on the probability ranking principle.