#7 - Pollster: When opinion researchers need a population

[Lillian_Jinyi]

I have a question regarding C). I totally get the negation test part why C is correct. But when I approach this question myself, I looked at C) and thought, hmm, what if it becomes different but in a way that MORE reflective of the entire population than the mandatory census, wouldn't the poll in the stim become even "MORE" accurate? I know I can always trust the negation test method, but I couldn't think of a reason to persuade myself why I shouldn't thinking about the direction of "difference" implying "being more accurate". Can you help explain why it is doesn't break the deal for C? Thank you!

[Jeff Wren]

Hi Lillian,

You're correct that the argument assumes that the group of people who would participate in a voluntary national census would differ in its demographic characteristics from the group of people who would participate in a mandatory national census specifically in a way that makes the poll results from voluntary census group less accurate. And this would be a good prephrase for the assumption answer choice.

However, in order to assume that the two groups will differ in that specific way, the argument must also assume more broadly that the two groups will differ at all in the first place. If they did not differ at all, then they certainly wouldn't differ in the specific way that the argument assumes that they would differ.

In other words, Answer C is more broad/less precise than the exact assumption that the argument is making, but it nevertheless is an assumption that the argument makes. You could think of Answer C as the assumption underlying the assumption that the argument really makes.

Just to be clear, the fact that the argument assumes that the two groups will differ in some way (as Answer C states) does not mean that the groups can differ in any possible way, just that they are in fact different, but the exact way that they need to be different is actually a second assumption.

Here's another example.

Imagine a different argument that assumes that the average global temperature will increase in the next twenty years.

Isn't it true that the argument also assumes that the average global temperature will change in the next twenty years?

Yes, since an increase is one type of change, then it is correct to say that the argument assumes that the average global temperature will change (specifically by increasing).

This is where using the Assumption Negation Technique can be really helpful in identifying assumptions that are not easy to recognize..