Slippery Slope and Heap "Fallacies"

Slippery Slope

Argument either (1) arguing from the vagary of the border to its nonexistence or all-too-easy passibility or (2) that some event will inescapably have certain consequences (usually alleged to be bad).

1. "A score of 32 deserved an A. A score of three points less -- of 29 -- also deserved an A. If scores three points apart deserve the same grade, then scores less far apart than that deserve the same grade! It's only fair. Every score deserves an A!"
2. "We have to take a stand against sex education in junior high schools. If we allow sex education in the eighth grade, then the seventh graders will want it, and then the sixth graders, and pretty soon we will be teaching sex education to our little kindergartners."

More Examples

• "We have to stop the tuition increase! The next thing you know, they'll be charging $40,000 a semester!"
• "The US shouldn't get involved militarily in other countries. Once the government sends in a few troops, it will then send in thousands to die."
• "You can never give anyone a break. If you do, they'll walk all over you."
• "We've got to stop them from banning pornography. Once they start banning one form of literature, they will never stop. Next thing you know, they will be burning all the books!"
• If we pass laws against fully-automatic weapons, then it won't be long before we pass laws on all weapons, and then we will begin to restrict other rights, and finally we will end up living in a communist state. Thus, we should not ban fully-automatic weapons.
• You should never gamble. Once you start gambling you find it hard to stop. Soon you are spending all your money on gambling, and eventually you will turn to crime to support your earnings.
• "If today you can take a thing like evolution and make it a crime to teach it in the public school, tomorrow you can make it a crime to teach it in the private schools, and the next year you can make it a crime to teach it to the hustings or in the church. At the next session you may ban books and the newspapers. Soon you may set Catholic against Protestant and Protestant against Protestant, and try to foist your own religion upon the minds of men. If you can do one you can do the other. Ignorance and fanaticism is ever busy and needs feeding. Always it is feeding and gloating for more. Today it is the public school teachers, tomorrow the private. The next day the preachers and the lectures, the magazines, the books, the newspapers. After while, your honor, it is the setting of man against man and creed against creed until with flying banners and beating drums we are marching backward to the glorious ages of the sixteenth century when bigots lighted fagots to burn the men who dared to bring any intelligence and enlightenment and culture to the human mind." (Clarence Darrow, The Scopes Trial, Day 2)
• Mom: Jeff! You know what happens when people take drugs! Pretty soon the caffeine won't be strong enough. Then you will take something stronger, maybe someone's diet pill. Then, something even stronger. Eventually, you will be doing cocaine. Then you will be a crack addict! So, don't drink that coffee.
• "A human egg one minute after fertilization is not very different from what it is one minute later, or one minute after that, and so on. Thus, there is really no difference between just-fertilized eggs and adult humans" (Fogelin and Sinnott-Armstrong, p. 360).
• If arguments like those presented by Brian Fahling prevail in a Pennsylvania courtroom, the completely untestable conjectures of intelligent design may receive the same weight in many of our nation's classrooms as the thoroughly tested and established theory of evolution. Should this happen, it is only a matter of time until neo-Nazis will demand that their belief that the Holocaust never happened be taught alongside the well-documented history of World War II. The Flat Earth Society will doubtless demand equal time in geography and physics classes. And 2+2=5 may well be taught alongside 2+2=4. (Norman Tepley, Detroit Free Press, Thursday Oct. 13, 2005, p.12A)

The Heap Argument

• Argues from gradualness with which the border is crossed to the impossibility of crossing.
• Classic Example: One grain of sand doesn't make something that wasn't a heap of sand a heap of sand. So, no matter how many grains of sand you add, you'll never get a heap!

Examples

• Dwayne can never grow bald. Dwayne isn't bald now. Don't you agree that if he loses one hair, that won't make him go from not bald to bald? And if he loses one hair after that, then this one loss, too, won't make him go from not bald to bald. Therefore, no matter how much hair he loses, he can't become bald.
• "Life must be caused by a divine spark. Consider that if you start with an atom and you add another atom to it, it won't be alive, right? And if you keep doing this, you'll just have a bunch of atoms and no life. You can't get a living thing that way!"
• Think about the animal kingdom. If you start with the most complex forms, you find that they are very similar to other, less complex forms. But this creates a moral problem. Consider that it isn't morally acceptable to kill a human. But where does it become morally acceptable? Where do you draw the line? You can't, so it must be morally unacceptable to kill rats in your house."