Though there are so many perception to social change within the liberal approach, some radical scholars group them into subjective idealist comp and the objective idealist comp. The subjective idealist is a comp of philosophers who believe that nothing exist in actual fact, what is believed to exist is merely a sensory illusion of the perceiver. There is no objective existence independently of that perceiver’s will and conscience. While objective idealism is a camp that accepts that there is objective existence independence of the perceptions, they believe that it is factual that man and word exist in actual sense. It also has many other approaches to the question of social change such as the religious and the social science perspective.
The radical approaches to social change questions some of the assumptions of the liberal views to social change, this school of thought began by Karl Marx and Fredrick Engels, later there immediate followers known as the classical Marxists such as the V.I Lenin. Also a group known as the Neo-Marxist comp took it up though they deviated a bit from some of the formulations of Marx and Engels.
In comparison among the liberal and Radical approach to social change, the first one is the mode of production, Marx considered economic relations too