STRAWMAN:

“This is just common sense the boarder wall would very quickly pay for itself”

Strawman is defined as a fallacy based on giving the impression of refuting an opponent's argument, while actually refuting an argument that was not presented by that opponent. You substitute a person’s argument with a distorted, exaggerated, or misrepresented version of the argument. One who engages in this fallacy is said to be "attacking a straw man".Trump saying that this is just common sense makes his viewers try to understand where he is coming from ad if perhaps they are in the wrong. This slightly aggressive phrase gives a exaggerated impression to his viewers attacking the opinions of those who disagree with him.