This is Mark's example of a slippery slope: If you try to debunk this then you are not intelligent and will never get a good job.

Mark's argument proposes that I must be stupid if I try to debunk his statement, but I could very well be mildly intelligent to even smart. It also says that if I am not intelligent I will not get a good job. It may be more likely to get a good job if I am intelligent however it is totally plausible that I may still get a good job even if I am not intelligent.