Politician: Union leaders argue that increases in multinational control of manufacturing have shifted labor to nations without strong worker protections, resulting in a corresponding global decrease in workers' average wages.
Conclusion
Legislators should reject this argument. (i.e. legislators should reject the pleas for strong worker protections that oppose increases in multinational control)
Evidence
The union leaders making the argument have a vested interest in seeing workers' wages remain high, so naturally they don't want multinational corporations to ship manufacturing jobs to nations w/o strong worker protections.
Evaluate
As soon as we see Flaw + Rebuttal + Vested Interest we might recognize one of the top 6 most common famous flaws, Ad Hominem, when an author rejects an argument because of its source, not its ideas.
Just because the union leaders have a vested interest in warning against multinational corporations outsourcing labor to countries where workers are paid less doesn't mean that union leaders are wrong to worry about this.
Shouldn't legislators be trying to keep as many manufacturing jobs as they can within the borders of their country?
The fact that someone has a vested interest (ulterior motive) doesn't mean their perspective is flawed or wrong. We need to engage with their reasoning and see if their logic makes sense.
Goal
Look for an answer calling out the Ad Hominem move, or an answer otherwise objecting that the legislators should be taking seriously the concern that multinationals are outsourcing manufacturing jobs to other countries.
Union leaders argue that there should be legislative resistance to multinational control over manufacturing, since multinational corporations are shifting labor to nations without strong worker protections.