Parkland 2016 Logic: The Science of Arguments
T/F Validity is that property of a deductive argument such that, if the premises are assumed to be true, the conclusion must be true
True
14) Appeal to Ignorance -asserts conclusion to be true because it is not known to be false
Currently, there is absence of knowledge about the causes of autism, and a great deal of research is yet to be done. Some research suggests childhood vaccinations cause autism in some children, but other studies have rejected this possibility. Therefore, I will decisively conclude that autism is caused by childhood vaccinations.
T/F The use of scientific laws with no exceptions is inductive
False
T/F The words "since", "because", "thus", and "for", are all premise indicators
False Thus is not
29 Types of
Informal Fallacies
Induction conclusions contain information that goes _____________ the information of the premises.
BEYOND
15) Hasty Generalization -in the process of generalization, particular members of a group are observed to possess or lack some trait, and then a generalization is made about that whole group
Bill is a surfer and an idiot. Ralph is a surfer, and he's an idiot. Joe is a surfer and is an idiot. So, it's like totally obvious, dude, that all surfers are idiots.
5) Appeal to Popularity Vanity (Apple polishing or Brown Nosing) -"the ego stroke" by complimenting them so they believe in the conclusion of whatever you are trying to persuade them in doing
Do you know why you should believe in Velikovsky's theory of cataclysmic evolution? Because you are intelligent, and sophisticated, and kind hearted and magnanimous, and also very attractive, if i may make an understatement. That's why.
17) False Cause Non Causa Pro Causa -"Not the cause for the cause" -usually attributing a supernatural being for the cause in the conclusion -two events happen at the same time and one is used as a cause
Every time I tap my foot, a baby is born in China. For the sake of the world population, I should stop tapping my foot!
T/F An argument can never use factual statements to establish a factual claim as the conclusion
False
T/F An argument may have either no conclusion or no premises
False
T/F An argument, in our sense, may be a mere screaming match
False
T/F Any argument based on a sign, symbol, or icon is deductive
False
T/F Legal argumentation is never analogical
False
T/F Logic has no connection to everyday rational activity.
False
T/F The future can be predicted with deductive certainty
False
T/F The strength of the inferential link must be stated explicitly
False
19) False cause Gambler's Fallacy -"taken fails in the past to increase odds of winning in the future" -but the gamblers odds of winning the next game are completely independent of his past record
For the last ten years at Christmas, our office has selected "Secret Santas" by randomly picking names out of a hat. Since I have never been Julie's secret santa, and since we have always had the same number of employees, it is more likely this year I will be selected as Julie's secret santa
Sound Valid Unsound Deductive Invalid Arguments Cogent Strong Uncogent Inductive Weak
Go back and look at chart
7) Argument against the person circumstantial -person making the argument has some perceived negative personal circumstance such as place of residence, employment, financial ties, group membership, voluntary associations, friendships, and son
I am absolutely repulsed by anyone who lives in the valley. Well, James lives in the valley , and he says global warming is real. So I think it's fake.
13) Appeal to unqualified authority -uses an unqualified position solely as the main support in the conclusion
I believe in the Loch Ness monster because my buddy Edgar says it exists, and Edgar is something of an expert. No, he doesn't have a degree or research experience on the subject. No, he's never been to Loch Ness and has not evidence beyond what he has read. But Edgar claims he's an expert. So I believe in the Loch Ness monster, too.
12) Red Heerring (or Smokescreen) -distracting the conclusion with pointless premises
I respect you for giving me a long detailed argument in favor of prohibiting the sale of bath salts, but now you want me to give reasons for my belief that bath salts should remain legal to sell. Well let me tell you something. One summer I took a cruise on the North Sea and it was absolutely the best experience of my life. The landscape with fjords is just breathtaking. We anchored off Norway and Sweden and Finland, but i like the coast of Denmark the best. Have you been there? You really ought to go.
21) Weak Analogy -self explanatory
If someone rents a piece of land and plants crops on itm the landlord is never permitted to come and take those crops for himself when harvest time arrives. Similarly, if couples enlist the services of a surrogate mother to provide them with a baby, the mother should never be allowed to renege on the deal and keep the baby for her own once it is born.
Deductive------>
If you determine that the inferential link is 100% certain
Inductive------>
If you determine that the inferential link is less than 100% certain
3) Appeal to popularity Direct appeal -sole reason to believe conclusion is a sharp distinction between us versus them, and the promise of being accepted
If you take the Oath to Kill, you will be our favorite new friend. You'll be so popular with us that we'll do anything for you; support you, help you, protect you. You don't want to be like the others. They aren't popular with us. So go ahead and take the Oath to Kill.
Identify Conclusion Indicator and Conclusion : If Bob makes the grade, then he goes to Harvard. Bob made the grade. Thus, Bob will go to Harvard.
Indicator: Thus, Conclusion: Thus, Bob will go to Harvard
4) Appeal to Popularity Bandwagon Fallacy -join inevitable success or irresistible movement
Mom, I ought to get my boyfriend's name tattooed in big gaudy letters wrapping around my body. After all, everybody else is doing it. I should give in and join the rest.
8) Ad Hominem Tu Quoque -person making argument is solely a hypocrite
My dad is teaching me that I should obey all the traffic laws when I drive by myself. But he breaks them whenever he can. So when I drive by myself, I won't follow his advice.
Informal Fallacy = ?
Not an error in logical form, but in content
Inductive=?
Not completely certain that the conclusion following the premises is true
16) False Cause Post Hoc -"after this, therefore, because of this" -usually two events and the first one is the cause of the second
One night I observed the conjunction of Venus and Saturn close to a crescent moon. The next day, I found a wallet with $500 in it. Those were my lucky planets!
10) Straw Man ("very sarcastic straw man") -ignores an opponent's actual position, and instead attacks a weak caricature(straw man) of the opponent's position -"straw man"=exaggeration
Our senator says he wants to balance the budget and reduce government spending. But do you know what he really wants? To let old people die and the sick suffer. He wants to starve children and ruin the future of the country, and then run off and live somewhere else. We have to stop him right away!
Strong can either be cogent or uncogent -Cogent = -Uncogent =
-strong inductive argument with all premises being true -weak inductive argument or at least one premise is false, or both (EVEN THOUGH IT IS STILL CATEGORIZED AS INDUCTIVE WHEN ASSUMING THE PREMISES ARE TRUE)
Steps to diagramming:
1) Assign numbers to each proposition in the argument 2) Next, identify the conclusion and place the circled number at the bottom of the diagram 3) Then identify the propositions that directly support the conclusion and place them above the conclusion on the same first tier. Draw arrows to show the inferential link 4)Further, identify the propositions that support the premises on the first tier and place them above the appropriate premises on a second tier and draw arrows showing inferential link
METHOD FOR EVALUATING DEDUCTION (CHART)
1) Assume all the premises are true 2) Check the truth value of the conclusion 2a) If the conclusion MUST be true, then the argument is valid 2a.) If all the premises are in fact true, then the argument is sound 2a.) If at least one premise is in fact false, then the argument is unsound 2b) If the conclusion is possibly false, the argument is invalid *based solely on the premises*
Method for Evaluating Induction (Chart)
1) Assume all the premises are true 2) Check the truth value of the conclusion 2a) If the conclusion is probably true, based soley on the premises, then the argument is STRONG 2a.) If all the premises are actually true, then the argument is cogent 2a.) If at least one premise is actually false, then the argument is uncogent 2b) If the conclusion is probably false, based solely on the premises, then the argument is WEAK
Summary ^^^^^
1) arguments are never "true" or "false". Only propositions are 'true' or 'false' 2)Propositions are never 'valid or invalid', 'strong' or 'weak'. They are are only either 'true' or 'false' 3)Deductive arguments are never 'strong' or 'weak', 'cogent' or 'uncogent'. Those terms apply only to inductive arguments 4) Inductive arguments are never 'valid' or ' invalid', 'sound' or 'unsound'. Those terms only apply to deductive arguments
If deductive argument is invalid, it should be ______ _______.
Rejected Immediately
11) Missing the Point -arguer leaps to conclusion that does not follow the premises
Sergeant, it's obvious how this man died. He has bite marks covering lower body. His legs are wet with canine saliva. His clothing has been ripped and torn by claws or teeth. He bled profusely from bite wounds to the neck. He has defensive wounds on his hands and arms. You don't have to be Sherlock Holmes to see the conclusion: He was hit by a car!
If argument is valid, then you have to determine if it is ______ or _________.
Sound, Unsound
Most inductive arguments are either _____ or _____.
Statistical, Probability
18) False cause Oversimplified Cause -there are multiple real causes, but only one real cause is to be taken as the sole cause
The humanitarian crisis is Somalia is a tangled web of factors: famine, religious war, poverty, ethnic strife, piracy, and more. But it all reduces down to one thing: ethnic tension. Below everything else in the situation, ethnic strife explains it all.
9) Accident -Takes a rather good general rule and misapplies it to an irrelevant case or instance
The nazis are at the door, and they are asking me if I know of any Jewish families in the neighborhood. I do know of one family, so I'll tell them, sine it is always wrong to lie.
6) Argument against the person abusive -person making argument has some perceived negative personal trait such as race, height, weight, appearance, gender, personality, etc.
The speaker tonight eloquently argued for his new theory of society. He made brilliant deductions and drew stunning inferences. He had tremendous evidence on his side. And he anticipated objections to his position and gave persuasive replies. But I reject his entire theory. Why? Because he is Asian, and i can't stand Asian people. So his theory must be wrong.
T/F "No A's are B's" is a universal negative statement
True
T/F "Statement" and "proposition" are roughly synonymous terms for a logical point of view
True
T/F "argument" and "inference" are roughly synonymous terms from a logical point of view
True
T/F An argument in our sense, requires that there be reasonable dispute about the truth
True
T/F Arguments based on causality are inductive in nature
True
T/F Evidentiary reasoning would include scientific field research, criminal investigation, and other sorts of inference based on fragmentary, incomplete or selective pieces of evidence.
True
T/F Generalization is inductive
True
T/F In an argument composed of one value judgement and other factual statements, the value judgement is usually the conclusion.
True
T/F Live is a reflexive relation
True
T/F Logic is the science of analyzing and evaluating arguments.
True
T/F Marriage is a symmetrical relation
True
PREMISES CONCLUSION true true true false false true false false
VALIDITY argument may be valid or invalid invalid argument argument may be valid or invalid argument may be valid or invalid
No argument of the form "All A's are B's, All A's are C's, so, all B's are C's" is ever _______?
Valid
20) Slippery Slope -rejects action because they believe it leads through a series of causal steps to an unacceptable final result
We shall refuse the gay couple permission to attend their High School Prom dance. If we allow them to attend, then there will be gays only prom dances. Then there will be no longer hetero prom dances allowed. Then being gay will be mandatory in high school. We dont want that. So, we shall have to refuse the gay couple permission to attend their high school prom dance.
If conclusion is probably false, then the argument is clearly ___________.
Weak
2) Appeal to pity -bases acceptance of conclusion solely on an attempt to elicit pity, sympathy, or empathy
Your honor, I really wish you would show mercy on me. I'm not rich, I'm not good lookin', and I got no talents. I just had to take it out on somebody when I shot those innocent children I'm the real victim. I'm the victim of society!
Arguments of induction can have two types of conclusions....
conclusion is 50% or less = weak inductive conclusion is 50% or more (but never 100%) = strong inductive
Horizontal Independent Pattern Diagram
each proposition separately gives reason to prove the conclusion to be true
Strong argument =
inductive argument that if all premises are assumed to be true, the conclusion is probably true as well
Weak argument =
inductive argument that if all premises are assumed to be true, the conclusion is still probably false
CHARACTERISTICS OF DEDUCTION
mathematical reasoning arguments from definition arguments from scientific laws arguments in syllogistic form categorical ^ hypothetical ^ disjunctive ^ logic of relations
Multiple Conclusions Pattern Diagram
multiple conclusions can be be drawn from one proposition (could be conjoined conclusions or could be separate ones)
CHARACTERISTICS OF INDUCTIVE ARGUMENTS
predictions based on past patterns statistical reasoning and generalizations arguments from probability appeal to qualified authority arguments based on signs, symbols, icons casual reasoning legal reasoning evidentiary reasoning moral reasoning
Vertical Pattern Diagram
propositions follow a north to south orientation
Premise Indicators
since (nontemporal meaning) as indicated by because for in that as (noncomparison meaning) may be inferred from given that seeing that for the reason that inasmuch as owing to
Conjoint Premises or Horizontal Dependent Diagram
the propositions are needed to be tied together in order to prove the conclusion true, so they are conjoined by a bracket with the arrow coming down from the middle of the bracket
Conclusion Indicators
therefore wherefore accordingly we may conclude entails that hence thus consequently we may infer it must be that whence so it follows that implies that as a result
T/F The difference between deduction and induction is the potential strength of the inferential link, or amount of logical support
true
Diagramming Extended Arguments
10%
Evaluating Deduction -Valid = sound or unsound -Invalid
10%
Evaluating Induction -Strong = cogent or uncogent -Weak
10%
example of weak
"Every Thanksgiving for the past three years, it has snowed. Therefore it will probably NOT snow on Thanksgiving this year."
example of strong
"Every Thanksgiving for the past three years, it has snowed. Therefore, it will probably snow on Thanksgiving this year."
Inductive Indicator Words
"It is probably true that" "it is more than likely true that" "It follows with a high degree of certainty that" "It is virtually certain that"
example of: Deductive--->Valid-----> Sound) =
"Munich is a city in Bavaria. Bavaria is part of Germany. So, Munich is a city in Germany." (Premises are actually true and the conclusion is true also)
example
"New York is north of Boston. Therefore, Boston is north of New York"
Valid vs. Invalid (Looking strictly at formal features)
"No reptiles are mammals. Therefore, no mammals are reptiles." -premises assumed to be true...conclusion must be true -the validity is strong "All chess players are gamers. Therefore, all gamers are chess players" -even though the premises could be considered true, the validity is weak and the conclusion is false
example
"Robert gave a very cogent argument for funding the new space program. But I hate Robert, so, I am against the new space program."
example of: Deductive--->Valid------>(Unsound) =
"Since the American Civil War happened before World War II, and World War II happened before World War I, then the American War happened before World War I." (At least one premise is false but the conclusion could be seen as valid if the premises were believed to be true
example of: Deductive---->Invaild
"Some animals are cats. Some animals have grey fur. Consequently, some cats have grey fur."
Deductive Indicator Words
"it is certain that" "it is absolutely clear that" "it follows with 100% certainty that" "I deduce that" "It definitely must be the case that" "It is doubtless that" "It cannot be false that"
example of: Inductive-----strong----cogent
"there are 100 marbles randomly distributed in a jar. 60 are red. 40 are blue. One marble is chosen at random from the jar. So the marble is probably red. (All premises are actually true, and the conclusion is probably true based on the premises)
example of: Inductive---- weak
"there are 100 marbles randomly distributed in a jar. 60 are red. 40 are blue. One marble is chosen at random from the jar. Therefore the marble is probably blue. (Conclusion is false based solely on premises)
example of: Inductive----strong---uncogent
"there are 110 marbles randomly distributed in a jar. 60 are red. 50 are blue. One marble is chosen at random from the jar. So the marble is probably red. (the conclusion is assumed to be true based on premises however one or more premises are actually false)
Easy example of diagramming an argument " (1) I think, therefore, (2) I am
(1) Premise: "I think" ! Inferential link, indicated by therefore (3) Conclusion: "I am"
1) Appeal to force -supports conclusion solely by a threat
And by the way, you ought to believe in the Loch Ness moonster, too, because if you dont, ill punch your nose, turn your ears in to cauliflowers and snap youyr head around 180*!
Deductive=?
100% Certain that the conclusion following the premises is accurate
Identifying Informal Fallacies (Type and Subtype)
29%
IDENTIFY CONCLUSION
5%
Induction/Deduction
5%
Valid-----> Unsound =? Example
A deductive argument that has at least one false premise or the validity is invalid (EVEN THOUGH IT IS STILL CATEGORIZED AS DEDUCTIVE WHEN ASSUMING THE PREMISES ARE TRUE) "All reptiles are fish All fish are mammals Therefore, all reptiles are mammals"
Valid------> Sound =? Example:
A deductive argument that is both valid AND has all true premises "All reptiles are animals. All crocodilians are reptiles. Therefore, all crocodilians are animals"
Formal Fallacy = ?
A flaw in an argument due strictly to the logical form of the argument (rather than the content of a premise)
Fallacy = ?
A logical flaw that makes an argument appear valid or strong when it is actually weak or invalid.
PREMISES CONCLUSION true probably true true probably false false probably true false probably false
ARGUMENT may be strong or weak weak may be strong or weak may be strong or weak
