Official Definitions + Some Examples Flashcards
What is Logic at first glance
the study of reasoning or thinking, how we SHOULD think not how we do
What is Logic for logicists
the study of arguments
What is an Argument?
A set of determinately true or false sentences with 3 elements:
1. One or more premises, which provide evidence or support.
2. One conclusion, which follows from or is supported by the premises.
3. A claim about the connection between the premises and the conclusion.
What are Premises
propositions or statements that provide evidence and support for an author’s conclusion
What are the three elements every Argument needs to have?
- One or more premises, which provide evidence or support.
- One conclusion, which follows from or is supported by the premises.
- A claim about the connection between the premises and the conclusion.
What is a Conclusion?
a sentence in an argument that represents the author’s assertion, should be supported by the premises
What is an absolute borderline case?
Is the following an absolute borderline case?
Fill in the blank: If a sentence is Vague it has ____?
Absolute borderline cases
What is a Deductive Argument?
An argument in which the premise(s) are claimed to lend absolute support to the conclusion.
What is an Inductive Argument?
An argument in which the premise(s) are not claimed to lend absolute support to the conclusion. Instead, the premises are claimed to make the conclusion probable or likely.
Fill in the blank: An argument is Deductively Valid if _____.
If it has NO counter-examples.
What is a counter-example?
A possible situation (or possible world) in which all of the premises of the argument are TRUE, and the conclusion FALSE.
[possible world where premises=true but conclusion=false.]
Is this argument Deductively Valid?
Fill in the blank: If an argument has counter-examples then it is _____.
Deductively Invalid.
When does an argument have High Inductive Probability?
If the truth of the conclusion is very likely given the truth of the premises.
Fill in the blank: If the truth of an argument’s conclusion is questionable or not very likely given the truth of the premises, then it has ____.
Low Inductive Probability.
What are the two conditions an argument needs to fulfill to be Sound?
It must be Deductively Valid and have TRUE premises.
True or False: A Sound argument can be Deductively Valid or Invalid.
False, a Sound argument can ONLY be Deductively Valid.
What is Monotonic reasoning?
Where adding new premises will not make an argument that succeeds in providing the claimed support for its conclusion to then fail to do so.
What is Non-Monotonic reasoning?
Where adding new premises could make an argument that succeeds in providing the claimed support for its conclusion to then fail to do so.
What kind of reasoning does an argument have if adding new premises jeapardizes the argument’s ability to maintain the claimed support for its conclusion?
Non-Monotonic.
What is a Fallacy?
A faulty argument or a faulty kind of argument.
What is a Fallacy of Relevance?
Where someone supports their conclusion with premises that are NOT relevant to the truth of the conclusion.
What is a Semantic Fallacy?
Where someone’s argument relies on words or phrases with ambiguous or vague meanings.
What is a Deductive Fallacy?
Where someone claims that the truth of their premises would provide ABSOLUTE support for the truth of the conclusion when in fact the truth of the premises would not.
What is an Inductive Fallacy?
Where someone claims that the truth of their premises would provide a certain degree of support for the truth of the conclusion when in fact the truth of the premises would only provide some significantly weaker degree of support.
What are the four types of fallacies?
Fallacies of relevance, semantic fallacies, deductive fallacies, and inductive fallacies.
What is an Ad Hominem argument?
When someone claims to support a conclusion by attacking the person who asserts the opposite.
Name the 7 most common Fallacies of Relevance.
Ad Hominem, Guilt by Association, Tu Quoque, Vested Interest, Straw Man, Arguments by Authority, Appeals to Ignorance.
Why is an Ad Hominem argument a fallacy?
Because the nature of the person putting forth the argument is irrelevant to the truth of the conclusion / premises.
Determine the fallacies: “This is especially weird when you consider that Senator McCain is a fierce supporter of the war in Iraq, which was fanatically promoted by an entire barnyard of chicken hawks.”
Ad Hominem fallacy. Attacking the Chicken Hawks to say that argument is bad.
What is a Guilt by Association argument?
When someone claims to support a conclusion by criticizing the company kept by the person who asserts the opposite.
aka, someone who is considered as bad or opposing shares the same opinion as the one side of the argument (usually the opposite), so therefore the other side is correct.
Identify the fallacies: “Some Republicans are claiming that Obama didn’t deserve his Nobel Prize. Al Qaeda and Hamas think the same thing, and they hate America and peace. Obama deserved his prize.”
Guilt by Association. Al Qaeda and Hamas agree with the opposing side (that Obama didn’t deserve it) and they are bad, so the opposite of what they think must be true.
What is a Tu Quoque argument?
When someone claims to support a conclusion by accusing the person who asserts the opposite of hypocrisy or inconsistency.
Identify the fallacies: “Some people argue that Stanford should not invite Donald to visit. But these people are the same liberals who talk on and on about diversity, but they don’t want the kind of political diversity on campus that Donald would bring. :. Donald should be on campus.”
Tu Quoque argument. They want diversity but not if that means accepting Donald / the diversity he would bring.
What is a Vested Interest Argument?
When someone claims to support a conclusion by alleging that someone who assets the opposite has an interest in doing so.
Identify the fallacies: “Some people argue that the federal gov. should allow drilling in the ANW Refuge. But these people are all from oil companies or are ex-oil CEOs, and they want the profit from new oil drilling. :. The fed. gov. should not allow drilling in the ANW.”
Vested Interest argument. They are claiming that all the people who support drilling only support it because it benefits them.
What is a Straw Man argument?
When someone claims to refute an assertion by attacking a much less plausible position similar to it. “Fighting against a straw man and claiming you defeated a real one.”
Identify the fallacies: “If abortion in all circumstances is made completely illegal, then there would be an explosion of dangerous back-alley abortions. Then, the number of abortions wouldn’t go down dramatically, but many women’s lives would be endangered. :. There should be no restrictions on abortion at all.”
Straw Man argument. The conclusion is way more drastic then the premises. The premises support the conclusion that abortion shouldn’t be illegal in all circumstances, not that there should be no restrictions on abortion at all.
What is an Argument by Authority?
When someone claims to support a conclusion by citing the opinion of someone (as evidence) without giving good reason to think that this person is reliable (or without removing a reason to doubt that the person is reliable).
Identify the fallacies: “My high school teacher said that the Magna Carta was signed in 1215. :. The MC was signed in 1215.”
Argument by authority. You are taking your teacher’s word/authority.
Identify the fallacy: “GW Bush says that Saddam Hussein definitely has weapons of mass destruction. :. SH has WMDs.”
Argument by authority. Taking the word of GW Bush.
What is Appeals to Ignorance?
When someone claims to support the truth of a conclusion by arguing that no one can disprove it.
Identify the fallacy: “Since we have not yet found weapons of mass destruction (WMD) in Iraq they must have existed and the administration is guilty of having invented a bogeyman.”
Appeals to Ignorance. They haven’t reported that there IS WMDs so that means there ISNT.
What are the two most common Semantic Fallacies?
Sorites argument and Fallacy of Ambiguity.
What is a Sorites argument?
When someone claims to show that something is an instance of a vague predicate (statement) by arguing incrementally (in a series) from a clear case.
Define Semantics.
Of or related to word meanings. So a semantic fallacy has things going wrong with word meanings.
Identify the fallacy: “JS is not bald. If you pluck one hair from a man who isn’t bald, that won’t make him bald.”
Sorites argument. Both premises are true, that is the clear case. However, if you pluck enough hairs (arguing incrementally), JS will become bald (resulting in the vague predicate).
Fill in the blank: If someone accounts for a new thing in an argument but later compares that to the original standard equally, then they have a commited a _______ fallacy.
Sorites argument.
What are the two conditions for someone to commit a Fallacy of Ambiguity?
1) must use a phrase with more than one distinct meaning, 2) the argument is only good if the phrase is used one specific way at one point in the argument, and then in another, different specific way in another point in the argument.
What are the 3 most common types of Deductive Fallacies?
Affirming the Consequent, Denying the Antecedent, and Circular Reasoning.
What does an argument in the form of Affirming the Consequent look like?
If A then B.
B.
:. A.
What does an argument in the form of Denying the Antecedent look like?
If A then B.
A is false.
:. B is false.
True or False: Deductive Fallacies must be deductive and valid.
False, Deductive Fallacies must be deductive and INvalid.
Identify the fallacy: “If i win the lottery, I will skip work tomorrow. I will skip work tomorrow. :. I win the lottery.”
Affirming the Consequent. It’s clear to see that just because B (skipping work) happens, that doesn’t mean A (winning the lottery) will simply because of that statement. For this to be logical, A must happen before B can come true.
Identify the fallacy: “If Pat is a priest, then Pat is a man. Pat is not a priest. Therefore, Pat is not a man.”
Denying the Antecedent. These two are not directly correlated enough to logically say that if Pat is not a priest then Pat is not a man. Just because A is false, doesn’t mean B is.
Which form is NOT a fallacy:
1) If A then B. A is false.
:. B is false.
2) If A then B. B is false.
:. A is false
2 because to be B, you musy meet the condition which is A. The other is the fallacy of Denying the Antecedent.
Which form is NOT a fallacy and why:
1) If A then B. A.
:. B.
2) If A then B. B.
:. A.
1 because you cannot be A if you are not B. The other is the fallacy of Affirming the Consequence.
What is Circular Reasoning?
When one of the premises in her argument assumes the conclusion.
Someone uses their premises to support their conclusion, but their premise(s) isn’t true unless you already assume the conclusion is true. What kind of fallacy is this?
Circular Reasoning.
True or False: an Inductive Fallacy must be inductive and have low inductive probablity.
True. Must have LIP.
What are the 5 types of Inductive Fallacies?
Hasty Generalization, Gambler’s Fallacy, False Cause, Conjunctive Fallacy, and Base Rate Fallacy.
What is a Hasty Generalization?
When someone infers that an entire class of things has some property based only on the fact that some of its members have it.
Is generalization bad? Why is Hasty Generalization a fallacy?
Generalization is not automatically a bad thing in an argument. Hasty Generalization particularly is a fallacy because an argument cannot be based SOLELY on that one generalization (or one property). The sample size must be representative of the whole class (can’t have special features).
Identify the fallacy: “The less sleep I get before a presentation, the better I do. :. People should sleep less before presentations.”
Hasty generalization. Because getting less sleep before a presentation works good for the author (sample size), they think it should work to everyone else (class)
What is the Gambler’s Fallacy?
When someone thinks that an event in a sequence of independent events is more likely to occur in a certain way because it has not occurred that way recently.
A man flips a coin 10 times. Each time it has landed on heads. He claims that the next time it will land on tails because it hasn’t done so in a long time. What kind of fallacy is this?
Gambler’s fallacy. The coin flips are events that are independent of each other, it will not matter how many times it’s landed on heads because its fully up to chance.
Identify the fallacy: “In the last 100 rolls, the dice have not come up snake eyes. :. Snake eyes are likely to come up soon.”
Gambler’s fallacy. It is up to chance, the amount of times rolled does not change the odds of getting snake eyes (1/36).
What is False Cause?
When someone concludes that A causes B only because A happens before or at the same time as B.
False Cause has a nickname: Post-Hoc-Ergo-Propter-Hoc. What does it mean in english?
After-this-therefore (:.)- because of-this.
Identify the fallacy: “In 1960s, drug use exploded. At the same time, male hair length increased dramatically. So we can infer that drug use causes longer hair.”
False cause. They are completely unrelated to each other!! Only correlation is that they happened at the same time which is not enough to prove an argument.
What is a Conjunctive Fallacy?
When someone believes that the conjunction / combination of 2 attributes or events (A + B) is more likely to occur than one of its parts (like A).
You are asked to rank these options out of probability: 1. bill plays jazz
2. bill is an accountant and plays jazz
3. bill is a social worker
4. bill is an accountant.
Which of these is logically impossible to be correct and what fallacy does it represent?
2 because it logically cannot be MORE probable than 1 or 2 because it is a combination of both. 2 can’t be true and 1 or 4 false. This is the Conjunctive Fallacy.
What is the Base Rate Fallacy?
When someone ignores the base rate of an attribute or event when inferring the likelihood of that attribute or event in a specific case given some evidence.
aka, favoring one specific rate (usually new evidence) and completely disregarding another.
What does Base Rate mean?
The probability you would assign to an event/attribute in a specific case given some evidence.
True or False: A deductively valid argument can have true premises and a false conclusion.
False. Any world where the premise(s) are true, the conclusion also has to be true - otherwise it is deductively INVALID.
What is a Deductively Valid argument?
An argument whose premise(s) lend ABSOLUTE SUPPORT to its conclusion and has NO counter-examples.
What is a Deductively Invalid argument?
An argument whose premise(s) lend ABSOLUTE SUPPORT to its conclusion and HAS counter-examples.
Fill in the blank: If an argument is inductive and the conclusion is likely to be true, then it has ______.
High inductive probability.
Fill in the blank: If an argument is inductive and the conclusion is UNlikely to be true, then it has ____.
Low inductive probability.
What is the Principle of Inductive Reasoning?
The set of premises of an Inductive Argument must contain all of the sentences that are known to be relevant to the truth of the conclusion.
aka, “only as strong as its weakest link” - you must consider all relevant premises to determine the strength of the claim.
Is the following argument deductive/inductive? Is it valid/invalid or HIP/LIP?
“The coin hasn’t come up heads in a very long time. I bet it will come up heads this time.”
Inductive - “I bet”
LIP - it will be a 50/50 regardless of premise’s claim.
Is the following argument deductive/inductive? Is it valid/invalid or HIP/LIP?
“2+2=5. Therefore, the Cubs won the 2003 World Series.”
Deductively Valid - violates #1 and #2 but has NO COUNTEREXAMPLES - no world where premise is true but conclusion is false (because premise can never be true)
Is the following argument deductive/inductive? Is it valid/invalid or HIP/LIP?
“The Cubs won the ‘03 WS. Therefore, 2+2=4.”
Deductively Valid - the premise is not factually true, but the conclusion is ALWAYS true, so there is no world where the premise=true and the conclusion=false (so no counterexamples).
An argument has a premise that is factually false and can NEVER be true. Its conclusion is also factually false. Is this argument deductively valid or invalid?
Deductively valid because there is no world where the premise is true and the conclusion is false because the premise will never be true, therefore it has no counterexamples.
Fill in the blank: An argument with a conclusion that is NECESSARILY true (aka, always true in every world) is it always _______.
Deductively Valid.
True or False: The more steps there are in an argument, the lower the inductive probability.
True.
Fill in the blank: A complex argument (one with intermediate conclusions) is only deductive if all its steps are _______.
Deductive.
True or False: A deductive argument should never violate #4.
True - “absolute support.”
Fill in the blanks: Monotonic Arguments are ________ and Non-Monotonic Arguments are _______.
Deductive, Inductive.
Is this format a deductive or inductive argument: “if A then B. A, so B.”
Deductive (it can never be inductive, so new evidence will not affect it no matter what).
