Final answer:
The passage commits an ad hominem circumstantial fallacy by suggesting that the teachers' opposition stems from fear of job loss, without addressing the substance of their argument.
Step-by-step explanation:
The argument given in the passage that "Of course the teacher's union is going to be opposed to merit pay for teachers.
The teachers are just worried about losing their jobs." commits a logical fallacy known as an ad hominem (argument against the person) circumstantial fallacy.
This type of fallacy attempts to discredit the teachers' union's position on merit pay by suggesting that their opposition is based solely on a fear of job loss, rather than on any substantive argument regarding the merit pay system itself.
It attacks the circumstance or personal situation of the teachers rather than addressing the actual argument or evidence concerning merit pay.