This is a clip from 1977 where Hayek discusses the fallacy of central planning in the area of “social justice”. The distributed nature of the knowledge needed in order to enact a just system of social order is simply not available nor obtainable by a single individual. No planning can be undertaken without such knowledge, hence it is fallacious to even discuss the concept of instituting an overarching plan for social justice. What seems just to one social group may not be just to another.
I may write a full paper on the topic in the future but Hayek, even in his old age, does a great job explaining it in this video.