Bird of Paradize

Tuesday, June 20, 2006

How to Spot Bad Argument

We're bombarded every day with people trying to convince us this or that is right and true. With so much information coming our way from so many different sources, how are we to decide what's credible and what's not?

Here are some well established techniques for spotting a bad argument presented in what I hope is a more entertaining way than usual. I've given each my own name, but I've also put the common technical term in brackets afterwards in case you want to do further research on this topic. All of these are well worth understanding if you aim to become a better thinker.

One final note before I get started. Please don't use the below to become an argument-nerd. If you catch yourself putting on a nasally voice and saying something like "You've just committed argumentum ad baculum my good chap", then you're taking this stuff way too seriously.

Instead, use them to make up your own mind about the truth of various statements. In our effort to save time, we all commit the offenses below more often than we probably should.

You're an idiot, so you must be wrong (ad hominem)
This is the "playing the man not the ball argument", where you attack the speaker and not what he's saying. If someone has to resort to this technique, you'll often find they haven't thought through their position very well. This form of argument goes on all the time in political circles.

Example: "Senator Morris used to be a member of the Communist Party, so no idea he puts forward about how to fix the nation's economic problems can be taken seriously".

The Bible says it's true, so it must be true (argumentum ad verecundiam )
This is also known as an "appeal to authority" and is very common. Just because a statement supposedly comes from a credible source, doesn't mean it's true.

Most of us rely on this one more often than we probably should. We're unlikely to investigate too thoroughly whether what a doctor says about our health is true, for example. He's a doctor, so we just assume he's right.

Because this is such a powerful form of poor argument, it's often used to trick people into believing something that may be false. Advertisers use scientific terms to sell their products, for example.

You can usually spot someone who's using this to cover up a weak position by pushing them to provide some evidence other than the authority to back up their claims.

Example: "My friend is a top programmer at Google, and this is the way he builds his systems, so it must be the best way".

All models are tall, Sally is tall, therefore Sally must be a model (affirming the consequent)
This is when you say an assumption works in both directions, even if there's no reason to believe so. Just because X means Y, doesn't mean Y means X, in other words. This can be a very subtle argument to catch out.

Example: "If my business partner was stealing from me, he'd probably buy himself a fancy car. He just bought a Mercedes, so he's probably stealing from me."

Evolution says men come from baboons - only an idiot would believe something like that! (straw man)
This is a very common form of poor argument. It involves misrepresenting your opponent's position, by pretending it's something that sounds similar but is easy to refute. This is used a lot in political or religious arguments.

Example: "The only reason you want to stop companies offshoring jobs to India is because you're a racist. No decent person can take such an argument seriously".

Britney Spears is the most popular singer in the world, so she must be very talented (argumentum ad populum )
This is the appeal to the majority argument. If enough people believe something to be true, then it must be, in other words. The problem is, history is full of examples of sincere majority beliefs eventually being proven false. Just because a lot of people think something, doesn't make it right.

Example: "Everyone thinks this is the best time to buy a house, so you should do it as soon as possible."

It's hot and the crime rate is up - therefore heat causes crime (correlation implies causation )
This is an easy one to catch people out with. Just because two things happen at the same time or in the same place, doesn't mean there's any kind of cause and effect going on. It may just be coincidence.

Example: "Every time Frank is on duty in the store something goes missing. That guy must be a thief".

Killing is wrong, therefore abortion is wrong (petitio principii)
This is a type of circular argument. Basically, it takes the form of putting the proof of your argument into one of the assumptions. The conclusion appears at the beginning and the end of the argument, so nothing of any substance is really created. It basically says X is true, because X is true. It can also take the form X is true because Y is true, and Y is true because X is true.

Example: "Only a loving God could have created such a wonderful world, therefore our world was created by a loving God".

Note: None of the above examples are intended to show any of the points of view presented are wrong, or belittle any religious or political belief. Please concentrate on the structure of the argument rather than the subject matter. I could just have easily have presented a false argument from the opposite position.

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