I think the distinction is a useful one to have, because it lets you identify the appropriate way to try to convince somebody. If people disagree about the eff

I think the distinction is a useful one to have, because it lets you identify the appropriate way to try to convince somebody. If people disagree about the effectiveness of policies, and which ones will bring about the desired effects, then additional evidence should be found and examined to determine who is correct. On the other hand, if people disagree about what the goal is, then no amount of evidence will convince them, because goals are unobservable.