assumption negation

[Hithere17]

Hi,

I'm hoping that you can help explain the assumption negation technique.

Here is a simple example.

Statement:
I am the best baker in Paris

Answer choices:
Anne is not the best baker in Paris
Pierre is the best baker in Paris
I work as a pastry chef at the Ritz Paris
Tran works as a pastry chef in my kitchen

Can you please explain how you would use the assumption negation technique here and how that would lead you to come up with the correct answer. If you could explain this system in simple terms that would also be helpful.

Thank you

[Adam Tyson]

I'll see what I can do, Hithere17!

It's going to be helpful for you to have a background in Conditional Reasoning in order to understand why the Assumption Negation TechniqueTM works. If you aren't yet strong on Conditional Reasoning, you'll want to study up on that.

The idea behind the technique is that, since the Assumption must be true (it is Necessary for the argument to be good), we can use the contrapositive of that conditional claim to help prove an answer choice. If we negate an answer choice and the result is that the argument is seriously undermined, then we know we have the right answer. It might help to look at this diagram of the relationship between the argument/conclusion (C) and the assumption (A):

Ctrue Atrue (if the Conclusion is true, the Assumption is also true)

The contrapositve of that relationship is:

Afalse Cfalse (if the Assumption is false, the Conclusion is false)

Now to your example. If the claim to be tested is "I am the best baker in Paris", what assumptions are present? I would probably start by prephrasing "there is no baker in Paris as good as or better than me".

Let's look at your proposed answer choices now and negate them:

A. Anne is not the best baker in Paris - negated, that becomes Anne IS the best baker in Paris. Assuming that I am not Anne, then this negation wrecks the argument and therefore IS an assumption of the argument. Winner!

B. Pierre is the best baker in Paris - negated, that's Pierre is NOT the best baker in Paris. Assuming that I am not Pierre, this negation strengthens the argument, and therefore is NOT an assumption. Remember, the negation should wreck the argument.

C. I work as a pastry chef at the Ritz Paris - negated, that would be I do NOT work as a pastry chef at the Ritz Paris. That negation does nothing to the argument. So what if I don't work there? I can still be the best, or maybe I am not. Without additional info (like "the best baker in Paris is the pastry chef at the Ritz), this answer is just irrelevant.

D. Tran works as a pastry chef in my kitchen - negated, Tran doesn't work as a pastry chef in my kitchen. Again, so what? What impact does that have on the claim that I am the best? None. Since the negation of D doesn't crush my argument, it is not an assumption of the argument.

Other assumptions are built into that first claim. I must be assuming that I am, in fact, a baker. I assume that I am in Paris, too.

I hope that was useful! For more help, check our online and printed resources, like the Logical Reasoning Bible, for further explanations and examples of both Conditional Reasoning and Assumption questions. Good luck in your continued studies!

[Hithere17]

thank you..

It does help a bit but am still not understanding why I need to "wreck" the argument in order to to see if the answer is correct.

[Adam Tyson]

That's the nature of assumptions, Hithere. If the conclusion is true, the assumption has to be, so if the assumption is not true then neither is the argument. Assumptions, when negated, destroy the argument, because the argument needs them to be true.

Use your example here to see why. If the claim is that you are the best baker in Paris, you have to assume that nobody is better, right? That's why "Anne is not the best" is the assumption - if Anne was the best, you could not be, right? Negating that answer wrecks your argument, so that answer must be an assumption of the argument. In other words, it has to be something that the author believes if they are to honestly make their claim. None of the other claims are things that you MUST believe in order to claim that you are the best baker in Paris. You might believe some of them, you might not, but you don't have to believe any of them other than that Anne is not the best (and nobody other than you is the best, either.

One more way to look at it - assumptions are unstated premises of the argument. Answer A works a premise to support that you are the best, but none of the other answers does that.

Keep with it and it should click for you soon. Good luck!

[Hithere17]

That is so helpful. Thanks for taking the time out to explain this.
Have a great weekend.