Using Logic to Analyze an Argument

Questioning Both Premises

Translating a sentence into “Logical English” may seem like extra verbiage which is only belaboring the obvious. However, writing out even a simple argument this way makes it much easier to analyze its strengths and weaknesses. Consider the following argument:

if Obama is a Muslim, he should not be president.

Obama is a Muslim.

Therefore he should not be president.

Logically, this is a completely valid argument. However, writing it in its complete logical form shows both reasons we shouldn’t accept its conclusion. We are only required to accept the conclusion of a valid argument if both of its premises are true, and in this case both premises are false. When people criticize this argument, they usually focus on the fact that the second premise is false, and muddle up their argument by throwing in occasional attacks on the first premise as well. The fact that Obama is not a Muslim is so easy to prove, and the idea that no president should be Muslim is so morally repellent, it is difficult not to jump back-and-forth between the two points. The rebuttal to this argument would be much more effective if each premise is attacked separately, preferably in two different paragraphs with different topic sentences. It’s rather like fixing a car. You are more likely to find what’s wrong if you analyze each part individually. Breaking an argument up into its logical form is the best way of doing this.

Here’s another example of an argument that sometimes gets confusing because people don’t separate the two…