Commentator: The theory of trade retaliation states that countries clo

You're supporting the conclusion WITH THE CONCLUSION.

The evidence doesn't say SHUT ALL.

Look again. The evidence is what matters here and you're missing a key detail of what the green part says.

Hi MartyTargetTestPrep - thanks for replying.

In the green part - i notice the word "Some"

So country (1) has a problem with country (2)

Country (2) lets say initiates the trade war and shuts down 5 of its markets. So five of Country 2's markets -- are not allowed to sell items to Country (1) specifically.

Country (1), in retaliation, shuts down 3 markets in retaliation vis a vis Country (1)

But again in the red-- the conclusion says : "If every country acted according to this theory, no country would trade with any other" ---

This red bit -- tells me that --- in the hypothetical scenario in the red -- Country (1) will shut down at least 1 market against all 199 countries.

YES, and you are ASSUMING that that conclusion is correct. You are basically assuming the correct answer to the question.

In other words, like the author of the argument, you are jumping from evidence about SOME markets to a conclusion about ALL markets.

OR maybe you are using the conclusion as evidence.

Either way, the point is that the evidence is about some markets, whereas the conclusion is about all markets, and the assumption has to fill the gap between the two.

Commentator: The theory of trade retaliation states that countries closed out of any of another country’s markets should close some of their own markets to the other country in order to pressure the other country to reopen its markets. If every country acted according to this theory, no country would trade with any other.

Theory of Trade retaliation = If country A closes doors to its markets for country B, then country B should also close doors to its markets for country A. This will pressurize country A to reopen its markets to country B. If every country acted acc to this theory, no country would trade with one another.
Conclusion: If all countries implement the theory of trade retaliation, no country would trade with one another.

The commentator’s argument relies on which of the following assumptions?

We need to identify the assumption

(A) No country actually acts according to the theory of trade retaliation.
Analysis: This speaks about the fact that no country actually acts according to the theory of trade retaliation. However, we are concerned about the hypothetical situation where all countries act according to the theory of retaliation.

(B) No country should block any of its markets to foreign trade.
We are not concerned with the actual facts. Therefore, "should" is not what we are looking for. We are looking for hypothetical scenarios.

(C) Trade disputes should be settled by international tribunal.
Who should settle the disputes is not the concern. We are concerned only about whether or not countries would trade with one another if a certain theory is adopted.

(D) For any two countries, at least one has some market closed to the other.
Negation: For any two countries, none had some market closed to the other.
Analysis: If the negation were true, then it follows that there will be at least two countries that trade with each other. Therefore, the conclusion falls apart. Keep it!

(E) Countries close their markets to foreigners to protect domestic producers.
We are not concerned about the reason for countries closing their market.

Therefore, the correct answer choice is (D)

D states the ans clearly. If you negate it, it will break the conclusion of the author

­Conc: If every country acted according to this theory, no country would trade with any other.

(A) No country actually acts according to the theory of trade retaliation - Notice the "if" in the conclusion, we're saying if X happens, then Y would happen. So to answer the question, we'll have to see if X leads to Y. The option just states Y doesn't happen, but doesn't explain the causal link between X and Y. X and Y being - "Acting according to theory" and "No trade". When given a conditional in conclusion, always be careful of the this type of trap. Also as an additional check - when negated this option can co-exist with the conclusion, i.e., some countries actually act according to theory of trade retaliation and some don't. This suggests that the conclusion is not invalid. Drop

(B) No country should block any of its markets to foreign trade - Should countries block their markets to foreign trade? Answering this doesn't seem to be the aim of the passage. Drop

(C) Trade disputes should be settled by international tribunal. - Who settles trade disputes? Not relevant to the conclusion. Drop

(D) For any two countries, at least one has some market closed to the other. This can be clearly assumed, i.e., if every country acted according to this theory, some if not all trade would cease to exist. Negate to check - For any two countries, none of them have some market closed to the other, i.e., all market are open to foreign trade. This means that even if countries follow this theory, everyone has an open market, meaning they do trade with one another. This breaks the conclusion. Keep

(E) Countries close their markets to foreigners to protect domestic producers - The reason for which countries close their market to foreigners is not relevant. Drop