My son Ben continues learning to become a critical thinker by grappling with logic. Logic is one of the more challenging topics students need to learn to become critical thinkers, not because the rules of logic are hard or complex, but because they are not intuitive. We’d prefer to judge an argument based on the initial impression it makes on us (especially if we disagree with it), rather than doing the work of translating it into a logical form and analyzing it.
But, as Ben learned, going through the process of logic-checking our arguments and those of others, gives you reasons to agree or disagree with something, which is generally superior to relying on your gut – especially when arguing over important (and often complex) matters. You can follow along with what Ben studied here.
In school debates, I was once taught how you could use rhetoric to distract from admittedly weak arguments. As I learned last time, arguments can do this by appealing to things other than pure logic. But when you debate, the most valuable skill is to be able to break an argument down to its raw form. While you shouldn’t deny the impact that pathos and ethos can have on people, no bells and whistles can save an argument from having weak logic.
Arguments consist of premises (the statements that support a claim) and a conclusion (the claim that is supported). To be valid, an argument’s premises must support its conclusion, so if you accept that the premises are true, the conclusion is true as well. For a valid argument to also be sound, the premises themselves must also be accurate.
For a number of reasons, an argument can lack either validity or soundness. For instance, if you are making an argument along the lines of…
Premise 1: If a, then b
Premise 2: b
Conclusion: Therefore, a
…you must be sure that b could not exist without a also being true. This mistake in logic is called affirming the consequent, in which a debater uses b, the consequent, as evidence that a is true, when this is not necessarily the case.. For instance:
Premise 1: All the primary suspects were questioned by the police
Premise 2: Frank was questioned by the police
Conclusion: Frank is a primary suspect
This leap of logic stems from the assumption that if both “primary suspects” and “Frank” fit under the umbrella of “people questioned by the police,” they necessarily overlap. But it could be that Frank, unlike the others that were questioned by the police, was innocent or questioned about an unrelated matter, and so was not a primary suspect. Presuming the premises are all true, the conclusion can be false, so the argument is not valid.
In a less obvious example, a news source might suggest that because the U.S. military used a tactic that’s also been used by a sinister, oppressive country in the past, the U.S. is similarly oppressive and bad, even if their context for using the tactic is completely different. The setup would look something like this.
Premise 1: The U.S. used a military tactic
Premise 2: Another nation used the same military tactic
Premise 3: The other nation is sinister and oppressive
Conclusion: The U.S. is sinister and oppressive
This argument is also invalid because even if all the premises are true, they don’t add up to support the conclusion. There is a way to make this argument valid, however:
Premise 1: The U.S. used a military tactic
Premise 2: Another nation used the same military tactic
Premise 3: The other nation is sinister and oppressive
[Implied Premise:] All nations that use this tactic are sinister and oppressive
Conclusion: The U.S. is sinister and oppressive
An implied or hidden premise that the news source did not say is highlighted, and if it’s true that all nations that use the tactic are sinister and oppressive, then the argument would be both valid and sound. But the new implied premise could easily be refuted by pointing out other things that make the oppressive and sinister nation bad, traits that the U.S. doesn’t share. Once there is a premise with a hole in it, the argument might be valid, but it is also unsound.
When I learned about logical arguments and hidden premises, I thought about all the arguments I have with people over who is the greatest athlete in different sports. One person might consider Brady’s six Superbowl rings as definite proof that he’s the best to ever play the game, while others might point out the role Brady’s teammates played in those victories. Number geeks might not care that Michael Jordan revolutionized basketball, not when his numbers don’t hold up to LeBron’s.
While some people are better at coming up with equations for judging athletic greatness than others — I was going for my third year in a row winning my March Madness bracket, damn you COVID! — these arguments are never-ending because they all rely on hidden premises that hinge on how you define the “Greatest of All Time” (the GOAT). We’re all working with the same premises involving data: the same stats, the same game history, etc. But if no one even spots (much less agrees on) hidden premises that define which numbers make you the GOAT, we’ll continue to argue over who is the greatest without getting anywhere.
But if you can break an argument down into premises that do or do not support a conclusion, you know that the person you’re talking with is actually making a cohesive claim, or whether there are holes in his argument. Once you know the ways logic can be used or misused, you can go into debates with reason on your side.
You can follow along with what Ben has studied here and here.
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