Good and Bad Arguments

Here at Ottawa Skeptics we hear a lot of arguments for the existence of strange things. Unfortunately, most of those arguments are ‘wrong’. Fortunately, we have tools in our critical thinking toolbox for dismantling arguments and finding out which ones have a yummy juicy centre worth keeping, and which ones are rotten and worthless. If you are unable to tell good arguments from bad ones you will end up accepting bad ideas as true.

What is an Argument?

An argument is what someone tells you to convince you of a conclusion. Every argument consists of premises and a conclusion. You probably encounter more arguments in your day to day life than you realize. Just reading the editorial and opinion section in the morning paper exposes you to dozens of arguments.

An argument is simply a set of premises and a conclusion. The premises are linked together with the conclusion using logic. A premise is a statement which is presumed to be true for the sake of the argument. For example: “Ottawa is the capital of Canada”. That happens to be true. If our next premise was “the parliament is in the capital of Canada,” then it would then be safe to conclude that “the parliament is in Ottawa.” If on the other hand, our first premise was “Toronto is the capital of Canada,” then our conclusion that “the parliament is in Toronto” would be invalid! A conclusion is invalid if the premises used to arrive at it are false. It’s similar to starting a trip in the wrong direction, no matter how good a driver you are, you’re going the wrong way!

When analyzing an argument, the first step is to make sure all the premises are true. If any of them are false, in most cases it’s safe to disregard the argument.

Careful though! Just because the premises of an argument may appear to be true, it does not mean that the argument should be accepted. If the premises are not supporting the conclusion in a logical way, then we have a logical fallacy. Logical fallacies are often quite tricky to spot, but with practice it is quite easy and fun. Before you can spot a fallacy, it is important to know what kinds there are. There are many fallacies, and experts disagree on how many there actually are, but there are a few key fallacies that I’ll introduce here:

Circular Reasoning

Circular Reasoning (aka Begging the Question) occurs when the acceptance of the conclusion is required to accept the premise.

Example: “You should believe me when I say UFOs exist because I saw one myself!”

Response: “I have to believe UFOs exist in order to believe that you saw one… It would be simpler to assume that you were mistaken until I am shown evidence”

Appeal to Popularity

Just because something is popular, it does not mean that it is true, works, or is good. It may be popular for other many reasons such as cultural influences, ignorance, or even really good marketing.

Example: “Millions of people take homeopathic remedies every year, therefore they must work!”

Response: “Other medical treatments have in the past have been very popular, like bloodletting and trepanation, that later proved to be useless or even dangerous. Popular does not mean effective.”

Appeal to Ignorance

A claim is not automatically true just because it has yet to be disproved.

Example: “You cannot disprove that Bigfoot isn’t lurking in the local forests, therefore he’s probably there!”

Response: “You cannot disprove that I have an invisible unicorn hovering above me, that doesn’t mean it’s there. Let me know when there is positive evidence that Bigfoot exists.”

Appeal to Authority

Let’s face it, we cannot know everything. It is often needed to refer to the judgement of an expert on a topic to convince others of a point. Unfortunately, even experts can be wrong, and they often are. Often times, it’s not even experts in certain field that are appealed to, it’s just a celebrity or a scientist in an unrelated field.

Example: “Robert F. Kennedy claims that childhood vaccines cause autism, therefore they should be banned!”

Response: “Robert F. Kennedy is not an autism researcher, he’s not even a biologist. Actual scientists that have studied this issue believe that vaccines are perfectly safe, and avoiding vaccines can be very harmful.”

Ad Hominem

You will hear this fallacy a lot in politics, whether it’s in the parliament, or on the campaign trail. It is simply an insult thrown at the opponent in the hopes that it will make the opponent’s argument look bad, even though the insult has no bearing on the validity of the argument.

Example: “Of course scientists don’t support alternative medicine, they’re all close minded atheists!”

Response: “A scientist’s metaphysical beliefs are irrelevant to the truth of the claims of alternative medicine.”

And More!

Check out these websites for the endless ways that an argument can go wrong!

http://www.logicalfallacies.info/
http://www.nizkor.org/features/fallacies/
http://www.csun.edu/~dgw61315/fallacies.html
http://www.onegoodmove.org/fallacy/toc.htm


23. December 2007 by Pat
Categories: Skepticism, Topics | Leave a comment

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