Logical Fallacies and Science In The Media Flashcards
What is a fallacy?
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A fallacy is an error in reasoning
Common errors that undermine the logic of your argument
What are logical fallacies?
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Logical fallacies are defects in arguments
They can be subtle and easy to miss
Arguments can be superficially convincing but ultimately weak because of one of these flaws
List some of the main fallacies.
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Non Sequitur (Does Not Follow)
False Analogy
Slippery Slope
False Cause (Post Hoc ergo propter hoc)
Circular reasoning
Argument to the person (ad hominem)
Appeal to authority
Argument from Personal Incredulity
What is meant by non sequiter (does not follow)?
A conclusion that does not follow logically from preceding statements or that is based on irrelevant data
Give an example of a non sequiter statement.
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Mary loves children, so will make an excellent schoolteacher.
Jenny drives a Mercedes. Jenny must be wealthy.
His apartment building is huge. His apartment must also be huge.
Billy is eating broccoli. Billy must love to eat vegetables
Give two scientific examples of non sequiter statements.
John successfully carried out a tissue stain in the laboratory therefore John should receive the Nobel prize
This drug successfully lowers blood pressure, therefore this drug must kill cancer cells
What is false analogy?
The assumption that because two things are alike in
some respects, they are alike in others
Examples of false analogy.
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Phones and bananas fit into the hand, therefore phones should be edible
Heroin and cannabis are both drugs. Heroin can be lethal, therefore cannabis should be illegal
Give an example of a scientific false analogy
If antibiotics treat bacterial infections, they should also treat viral infections
What is a slippery slope fallacy?
Asserting that if we allow A to happen, then Z will
consequently happen too, therefore A should not happen
Give some examples of slippery slope fallacies.
If we allow abortion, soon it will be legal to kill children
If we legalise drugs, everyone will become a drug addict
Legalizing divorce is undesirable because it would cause more families to break up, which would finally result in the destruction of civilisation
Give an scientific example of a slippery slope fallacy.
Genetic modifications of embryos will lead to designer
babies and eugenics and so should not be allowed
What is False Cause (Post Hoc ergo propter hoc)?
The assumption that because two events occur together, or in sequence, one must cause the other
Give some examples of false cause fallacy.
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Before women got the vote, there were no nuclear weapons. Therefore, women voting caused the development of nuclear weapons
Roosters crow just before the sun rises. Therefore, rooster crowing causes the sun to rise
Most couples that divorce see a therapist before the separate. Therefore, therapists cause divorce
What is correlation?
Association between variables
What is causation?
One variable causes the other
Give a scientific example of false cause fallacy.
A child develops autism shortly after getting the MMR
vaccine, therefore the MMR vaccine causes autism
What is circular reasoning?
A is true because B is true; B is true because A is true
Give an example of circular reasoning.
The Bible tells us that it is the word of God
The word of God is infallible
Therefore the Bible is infallible
What is argument to the person (ad hominem)?
An attack on the person proposing an argument rather than on the argument itself.
Give an example of argument to the person (ad hominem) fallacy.
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There are stories that Prof. O’Brien is an adulterer, therefore his research is not worth considering.
Prof O’Brien’s research says drinking alcohol is bad for you, but he drinks alcohol, therefore his research is not valid.
What is Appeal to Authority?
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Person A is (claimed to be) an authority on a subject .
Person A makes claim about that subject.
Therefore, the claim is true.
Give an example of appeal to authority fallacy.
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“Prof. O’Neill is a respiratory physician that doesn’t believe smoking causes cancer.
Therefore, smoking doesn’t cause cancer”
What is Argument from Personal Incredulity?
I cannot explain or understand this, therefore it cannot be true
Give an example of an argument from personal incredulity.
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The creationist (“intelligent design”) argument - there are features of the natural world that we cannot explain. This is taken as evidence that God designed all creatures as they exist today and evolution is incorrect
“I can’t believe that something as intricate as an eye could come about by random mutation”
