Early in the section of Churchland's essay entitled "Arguments Against Dualism," he poses the question, "Can the dualist tell us anything about the internal constitution of mind stuff? Of the non-material elements that make it up?" (Churchland, p.315). He goes on to reply that the dualists have made no such explanation. However, this interjection is begging the question since it involves the assumption that mind stuff consists of elements, and furthermore that such elements are comprehendible to the human mind.
Churchland's next argument is directed at the substance dualist's views. He concludes that if the mind is dependant on the physical brain only for sense experience as said by the dualist, then damage to the neural tissue would not affect rational thought. Yet if the mind is a separate entity dependant on the physical brain for sense-experience, then damage that causes the ceasing of input from the brain would impair thought. In this way, the body is dependant on food (a separate entity) for nutrients; if food is not taken in, the body cannot sustain its functions.
Churchland's final argument against dualism is called the "argument from evolutionary history," and states that there is no evolutionary basis for the origin of the non-physical mind. The evolution of physical things involves the belief that all physical things evolved from chemicals in "space," that were prompted by electricity to form life. These chemicals referred to as our physical origins have no explanation of their appearance. Why then must there be an origin for non-physical stuffs?