Know when you're using one and know when one is being used:
Grammar Girl quick and dirty tips - on grammar
What Is a Straw Man Argument?
I always think of the Straw Man from The Wizard of Oz, but that's not the real origin. In its simplest definition, straw man is the name of a logical fallacy, which means that if you carefully dissect the argument or statement, it doesn't make sense. Debaters invoke a straw man when they put forth an argument—usually something extreme or easy to argue against—that they know their opponent doesn't support. You put forth a straw man because you know it will be easy for you to knock down or discredit. It's a way of misrepresenting your opponent's position.
It's as if you took a flaming scarecrow, threw it onto the debate floor, yelled “Look, it's my opponent's dangerous straw man,” and then you appeared to save the day by dousing the flames with water. All while your opponent mutters, “That's not my straw man. What just happened?”
It can be annoyingly effective because in response you may be lured into clarifying what your position is not instead of talking about what your position is, and studies have shown that when you repeat a lie, even if you are repeating it to refute it, the repetition can make people more likely to believe that the lie is true (1).
How Does the Straw Man Argument Work?
A straw man argument can be annoyingly effective because in response, you often have to spend time clarifying what your position is not instead of what your position is.
Here's an example. Let's say you believe genetically engineered crops should be more regulated, and your opponent believes genetically engineered crops should be less regulated. Your opponent could use the straw man technique by saying something like “If we take away farmers' ability to grow genetically engineered crops, if we eliminate that option, people will go hungry, nay, people will starve. Unlike my opponent, I choose to use the technology available to us and save lives.”
In that statement, your opponent has argued against eliminating genetically engineered crops instead of against simply increasing regulation. He's put up a straw man—no crops at all, people will starve—so he can knock it down.
Another Straw Man Argument Example
Here's another example. Maybe you're arguing with a friend about global warming. You think the government should raise fuel efficiency standards to cut down the amount of C02 we release over the next 20 years. Your friend thinks cars have nothing to do with it, and as you argue, he says something like “Our cities are built so that we have to drive cars. Your solution will kill the economy. How would people get to work without cars? It'll never work.”
You're twitching because your friend has thrown out a straw man argument. He's responding to an extreme version of your proposal that's easier to shoot down than your real proposal. He's arguing against the extreme idea that we need to get rid of all cars because it's easier than arguing against the moderate idea that we need to raise fuel efficiency.
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If that doesn't help you understand it here's Wikipedia :
A straw man is a common form of argument and is an informal fallacy based on giving the impression of refuting an opponent's argument, while refuting an argument that was not advanced by that opponent.[1] One who engages in this fallacy is said to be "attacking a straw man".
The typical straw man argument creates the illusion of having completely refuted or defeated an opponent's proposition through the covert replacement of it with a different proposition (i.e. "stand up a straw man") and the subsequent refutation of that false argument ("knock down a straw man") instead of the opponent's proposition.[2][3]
This technique has been used throughout history in polemical debate, particularly in arguments about highly charged emotional issues where a fiery, entertaining "battle" and the defeat of an "enemy" may be more valued than critical thinking or understanding both sides of the issue.
Allegedly, straw man tactics were once known in some parts of the United Kingdom as an Aunt Sally, after a pub game of the same name where patrons threw sticks or battens at a post to knock off a skittle balanced on top.[4][5]
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If that doesn't help here's Meriam-Webster definition:
:
a weak or imaginary opposition (as an argument or adversary) set up only to be easily confuted
:
a person set up to serve as a cover for a usually questionable transaction
Link: http://www.quickanddirtytips.com/education/grammar/what-is-a-straw-man-argument?page=1