Module 1: Intros Argument structure and basic reasoning Flashcards
argument components
an argument is made up of premises and a conclusion
Propositions
claims or parts of information building up an argument
- universal sentences
-propositions are broken down to premises and conclusions
Properties of propositions
-they have truth value
- they are shareable
- they are inter-translatable
Premises
The reasons presented to persuade someone that a conclusion is true or probably true
-are propositions that are used in support of the conclusion in a given argument
Conclusion
a judgement based on the information obtained through the premises
- proposition that sets out to prove in a given argument
Deductive reasoning
-from general to specific
-if all the premises are true then the conclusion must be true, aims to prove the conclusion with certainty
- a good deductive argument is both valid and sound
soundness
a valid argument where the premises are actually true
- relies on validity and refers to the content of the argument specifically the truth of the premises
- if an argument is sound then the conclusion is true
an argument can be
- valid and sound
- valid but unsound
- invalid and unsound
arguments cannot be invalid but sound, true or false
truth preserving
a characteristic of a valid deductive argument in which the logical structure guarantees the truth of the conclusion if the premises are true
inductive reasoning
specific to general
- aim to show that the conclusion is probably true
- can be strong and cogent
Example of deductive reasoning
-all cats are born with nine lives
-Felix is a cat
-Therefore Felix was born with 9 lives
Example of inductive reasoning
-Every time I have walked by that dog, he hasn’t tried to bite me
-so the next time I walk by that dog he wont try to bite me
Strength
an argument is strong hen the premises are true which means that the conclusion is probably true
- corresponds with validity
Cogency
is a strong argument which has true premises
- corresponds with soundness
types of valid arguments
- Modus Ponens
- Modus Tollens
- Hypothetical Syllogism
- Disjunctive Syllogism
- Reducitio ad absurdum
- Modus Tollens
-Denying the consequent (then clause)
if P then Q
not Q
therefore not P
-valid and sound
types of invalid arguments
- Affirming the consequent
- Denying the antecedent
- Disjunctive Fallacy
- Ad Hominem
- Strawman Fallacy
- Appeal to Authority
- False Dilemma or False dichotomy
- Slippery slope fallacy
- Begging the question
- Equivocation
- Post hoc ergo Propter hoc
Disjunctive Fallacy
either P or Q
not P
therefore not Q
INCLUSIVE OR
1. I will have a sandwich or a cup of coffee after work
2. I will have a sandwich after work
3. Therefore i wont have a cup of coffee after work
-invalid and unsound
Disjunctive Syllogism
either P or Q
not P
therefore Q
EXCLUSIVE OR
- Serena or Venus won the tennis match
- Serena won the match
- Therefore Venus did not win the match
Hypothetical Syllogism
if P then Q
if Q then R
therefore if P then R
- Either there is tea in my mug or there is coffee in my mug
- There is not tea in my mug
- Therefore there is coffee in my mug
-valid and sound
Reductio ad absurdum
kind of reasoning where you accept some hypothesis for the sake of argument and then you show that the hypothesis leads to a contradiction. The arguer assumes the opposite of the conclusion they want to prove to show that it leads to a contradiction
If P then Q, not Q therefore not P
Fallacy
a mistaken belief especially one based on an unsound argument
Consequent
last half of a hypothetical proposition whenever the if clause precedes the then clause
Antecedent
first half of a hypothetical proposition whenever the if clause precedes the then clause