Critical Reasoning

Historian: The vast majority of scholars studying the American Civil War regard Confederate generals as superior to their Union counterparts. They also acknowledge that the Confederate soldier was, on average, more committed to the cause and, therefore, willing to fight harder than the Union soldier. However, most of these same scholars agree with my contention that when the Civil War began in 1861, it was already true that the Confederacy could not prevail without the intervention of a major foreign power such as Great Britain or France.

Which of the following, if true, most strengthens the historian's contention?

(A) Both the Confederate and Union troops started the war using similar single-shot muzzle-loading guns to which bayonets could be attached.
(B) The Confederacy had a greater proportion of officers who had attended the United States Military Academy at West Point and had served with distinction in the Mexican War.
(C) The Union had four times the total population of the Confederacy and most of the industrial manufacturing in North America.
(D) The Confederacy won several important victories early in the war and earned the respect of foreign leaders.
(E) By the end of the war in 1865, many Union soldiers were armed with the new Spencer repeating rifles that fired seven shots before reloading; the Confederate army continued to rely on slower, single-shot weapons for its soldiers.

OA: C

The conclusion is that the Confederacy could not prevail without the intervention of a major foreign power. But C only talks about Union, so in a way it does not directly strengthen the conclusion!? Please explain.

You have correctly identified the conclusion. Once that is done, we can use the why test to determine the premises in the argument that support the conclusion.

Unfortunately, there are no premises in the argument that support the conclusion. In fact, the argument contains two counter premises:

1. Confederate generals were superior to Union generals.
2. Confederate soldiers were more committed to the cause.

Why, then, should we think that the Union would prevail unless the Confederacy could obtain the intervention of a major foreign power?

Just as the why test can help us find the premises in the argument, so too the why test can help us to find the right answer to a strengthen/support question. Let's use the why test with choice (C).

The Confederacy could not prevail without help. Why?
Because the Union had four times the total population and most of the industrial manufacturing.

Does that answer the question why? I think it does.
Answer (C) provides more than just information about the Union. It provides relative information about the Union compared to the Confederacy.