Getting Started 4 – Argument Health Check


Last time, I showed how a real-world argument contained in an editorial can be structured with premises leading to a conclusion. Once put into this format, the argument can be analyzed to determine if it’s any good.


A couple of additional concepts will help you do this yourself as you think through election and other news coming your way.


Will Trump resign?


To illustrate these concepts, I’ll use a news story that, like many news stories these days, rapidly found its way from Twitter to the mainstream media. The story predicted that President Trump would resign to avoid impeachment, blaming health concerns. The evidence supporting this claim was an unscheduled recent visit by the President to his doctor.


If we put aside psychological factors behind such an argument (such as wishful thinking on the part of Trump’s opponents, or suspicions by supporters of a conspiracy to get him to leave office), the argument we can distill from the stories linked above is a relatively simple one:


Premise 1: Donald Trump regularly boasts about his excellent health.

Premise 2: Donald Trump had an unscheduled visit to the doctor.


Conclusion: Donald Trump is about to resign citing health concerns, but really to avoid impeachment.


A valid concern?


Now that the argument is properly structured, the first step in the logic-checking process is to test the argument for validity.


In a valid argument, accepting the premises as true requires you to accept the conclusion as true. So the test for validity is a simple one: ask yourself if you have to accept the conclusion if you accept all of the premises in the argument as true.


In this case, it is easy to reject the conclusion after accepting the premises since there are any number of counter-examples one can come up with in which the premises are true but the conclusion false. For example, President Trump may have gone to the doctor because he had a virus, stomach trouble, back pain or any of a hundred other reasons anyone visits the doctor.


The ability to accept the premises but reject the conclusion makes the argument invalid and since validity is required of any good argument, it is fair to reject this one.


What's hiding in the argument?


Now we could fix our argument by adding one more premise that is implied but not stated outright in original argument which would make it look like this:


Premise 1: Donald Trump regularly boasts about his excellent health.

Premise 2: Donald Trump had an unscheduled visit to the doctor.

Premise 3: The only reason Donald Trump would go to his doctor for an unscheduled visit is to be able to claim his upcoming resignation is due to health problems, not from the threat of impeachment.


Conclusion: Donald Trump is about to resign citing health concerns, but really to avoid impeachment.


Adding that hidden premise (called an enthymeme for your Latin fans) actually makes the argument valid. (If you repeat the test for validity on this new version, you’ll find that you cannot accept the premises and also reject the conclusion.) But here we come to the second test of a good argument: a test for soundness which is based on whether or not the premises are actually true.


Sound reasoning?


If even one premise in a valid argument turns out to be false (or at least easily doubted by a reasonable person) then the whole argument fails due to being unsound. Given this, the easiest premise to reject would be the new, previously hidden one we just added since it presumes there is only one reason for the President to visit the doctor (as cover for resigning). As you just read, however, however, there are many possible (even likely) reasons he could have visited his doctor that have nothing to do with resignation or impeachment.


Note that just because an argument is invalid or unsound does not mean the conclusion isn’t true. It just means that the argument does not provide adequate reasons to believe the conclusion, either because the logical connection between premises and conclusions (the warrant) is weak, or the premises upon which the argument is based are faulty.


Keep validity and soundness (and argument structure) in mind since they will be playing big roles as we continue to explore how to approach the news as critical thinkers, rather than passive consumers (or sheep).

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