Critical legal thinking Flashcards
disjunctive syllogism
a valid argument pattern. It is valid regardless if is inclusive or exclsuive
P or Q
Not P
Therefore q
Affirming a disjuct
Occurs when the ‘or’ is not specified as being exclusive. It is invalid unless the or is specified as exclusive
P or Q
P
Therefore not Q
The above are invlalid unless or is exlcusive
Exclsuive
Exactly one can be true, they cannot both be i.e. you are alive or dead
Affirming the consequent
If P then Q
Q
Therefore P
This is a formal fallacy
Illicit conversion
A conditional sentence that tries to entail the converse
If P then Q
If Q then P
All P are Q
Therefore
All Q are P
OR
Some P are not Q
Therefore
Some Q are not P
Arguing from analogy
P and Q are similar in respect to properties a, b, and c.
P has been observed to have further property x.
Therefore, Q probably has property x also.
this is an inductive argument
When courts are faced with the ‘same’ case, they both have the same ratio, as use the same precedent.
If use an analogy then the cases don’t share a ratio, courts will extend the precedent to an analogous case- they will have the same outcome but for DIFFERENT REASONS.
previous case- the source
case looking at - the target
Argument’s by analogy do not purport the conclusion to be necessarily true.
‘L,M and N’s characteristics are RELEVENT to one’s success as a salesman.
This was shown in Adams v New Jersey Steamboat.
Conclusions in legal arguments should be presented as certain- instead of probably can say;
unless there are no countervailing considerations
there are no countervailing considerations
conclsuion as is certain
‘unless there are no countervailing considerations X has the characteristic y’
Applying a precedent to a non-analogous case
this is binding and content independant
Applying a precedent to an analogous case
this is content indepednent
Straw man
Change the argument that they have put forward in order to suit your argument. You distort their argument.
Fallacy Fallacy
To infer from the fact that a certain argument is fallicious then conclusion is false
Universal modus ponens
All men are mortal
Socrates is a man
Therefore
Socrates is mortal
For every x if x is a reasonable person then x would’ve foreseen the act.
The accused is a reasonable person
therefore
The accused would’ve foreseen the act
Validity
when an argument follows on from the premises. It is impossible for the conclsuion to be false if the premises are true
Modus tollens
If p then q
Not q
Therefore
Not p
Modus ponens
If p then q
p
therefore
q
why use legal sources
They are used because they are authoritative
They represent genuine wisdom, experience and information
Genuine authority is content independent
Persuasive authority- can decide whether to apply or not
If the user believes in the substantive soundness of the argument
Then even if it is traditionally it is known as an authority it is not being used as one
How do you overrule binding authority
must be compelling interest rather than a;
rational interest
Substantive interest
Legitimate interest
Thee interests are not applicable, must be COMPELLING interest.
Prohibited Authority
When court denies absolute authority, i.e. banning the use of wikepedia as an authority also wary of foreign law
‘The boundaries of law are set by the boundaries of legal authority and law speaks as law through sources’
‘The idea of authority’
Formal Fallacies
Affects the validity of the argument, they are not a formal valid pattern. It is a flaw in the structure.
Informal fallacies
They are formally valid and maybe sound
Non sequiter
Concusion does not follow from premises
Denying the antecedent
You are inferring the inverse from the original statement - often called illicit inversion
If P then Q
Not P
Therefore not Q
This is a formal fallacy
Affirming the consequent
You are inferring the converse of the original statement- often called illicit conversion/ converse error/fallacy of the converse
If P then Q
Q
Therefore P
- The defender is a foreign national or a diplomat
- The defender is a foreign national
Therefore - It is not the case that he is a diplomat
This is an example of the fallacy- Affirming the disjunct
It is invalid- we do not know whether the disjunct is exclusive
This occurs when ‘or’ is not specified as being exclusive - taking that if one option is true the other is false.
false Dichotomy
This is an informal fallacy
It involves claiming there are only 2 options when in fact there are more. You are falsely treating the disjunction as exhaustive and not taking into account other possibilities
Either God exists or the word would not have come into being
The world came into being
Therefore
God exists
Suppressed evidence
This is an informal fallacy - a fallacy of presumption
When you ignore an important peices of evidence in favour of your argument
- Generally streets are safe to walk down
- Therefore this street should be possible to walk down without harassment
Normative conclusion
If a statement renders a judgement then it is normative
‘you ought to do something’- this is normative
‘you are doing something’- this is descriptive
No normative conclusion can be drawn from non- normative premises
‘I have a liberty to vote’
This is an absense of duty
A liberty entails the correlative ‘no right’
‘to be owed a duty by someone else’
this is a claim right - a right in the strict sense
Charity
Reconstruction faithfully and completely captures the argument
No argument is refuted unless it is refutes in it’s strongest sense- otherwise have a straw man and are arguing against an argument that is not really being endorsed by the arguer
Straw man- fallacy of relevence
Fallacy of irrelevant conclusion
ignoratio elenchi
any argument for a conclsuion irrelevant to what is actually being argued
Exhaustive disjunction
Doesn’t leave room for other possibilities, nothing is left to the imagination
‘Every human is either a man or not a man’
Non- exhaustive
Leaves room for other possibilities
‘Every human is either a man or a woman’
You can get intersex people
Tertium quid
There is a third unlcassified reason
Inclusive
Means at least one is true, maybe both
Exclusive
Exactly one can be true, they cannot both be
Fallacy Fallacy
Because an argument is fallacious that it’s conclusion is false- you commit a non sequitar
1. Argument X is fallacious
Therefore
2. The conclusion of argument X is false.
The premises only concludes that Argument X FAILED TO ESTABLISH the conclusion
Hypothetical syllogism
If P then Q
If Q then R
Therefore if P then R
this is valid argument form
internal justification
this is about the relationship between components of the argument- the syllogism needs to be valid and sound- to be sound we need external justification.
A legal syllogism is valid only if it is internally justified.
Arguing in the alternative
Either consideration is presented as sufficient to establish the conclusion- when taken individually they are considered sufficient.
Seen as a disjunct then 2 premises- each to affirm each disjunct.
Cumulative arguments
Taken together they are sufficient
Here the antecedent of the conditional is a conjunction- ‘and’.
You only need to refute one premise to refute the argument
What is a reason
If it is a reason for something then it counts in it’s favour.
pro tanto reason
A reason which does not conclusively determine it, they can be outweighed by countervailing considerations
conclusive reason
a reason not open to being outweighted
If the wine list is good then we should go to the restaurant
this reason is being given as sufficient
If the wine list is good and there are no countervailing considerations then we should go tot he restaurant
The wine list reason is now being presented as a pro tanto reason in favour of the conclusion
Reason for action
This is a practical reason i.e. you have fallen and you ask for help.
If you promise to go for lunch- this promise is nothing to do with the merits of the action, the promise gives you reason to do the action- it is independent of the content of the promise and independent of the merits of the action you have promised.
You can have substantive reasons as well which are content dependent i.e. you have not seen them for a long time.
If someone is hurt and they need help- this is content dependent and is a substantive reason
Authority
Can be reasons for action (practical)
There can be reasons for belief (theoretical)
Authority is content independent
A scientist believes global warming
He has a substantive reason to do so which is content dependent- whereas our belief in global warming is content independent and is theoretical
An officer telling a soldier to clean his gun
The officer is giving a Practical content independent reason- a reason for action- the officer is a practical authority
Reasons for Belief
These are theoretical reasons- they are persuasive
1. If Lord Reid says P then we have reason to believe P.
2. Lord Reid says P
Therefore
3. We have reason to believe P
Authoritative pronouncements always depends on a normative claim that is not derived from a normative source i.e.
If commander x tells me to do A then I OUGHT to perform action A
Accepting authority
Requires substantive reasons to do so
Fallicious arguments from authority
ad verecundium
this sis when you try to appeal to a conclsuion because an authority said so or agrees with you- therefore that the other party should not question their authority.
protasis
antecedent- the ‘if’
Apodisis
consequent - the ‘then’
Tautology
‘if the will was not signed by Jeremy then the will was not signed by Jeremy’
When the same sentance features as both the consequent and the antecedent- they are always true- if p then p. They are always valid.
a.
b.
Probably
c.
This is invalid, but we cannot critisise it as it does not purport to be establish certainty only probability- it does not put itself foreward as a valid argument
Deductive arguments
If they purport to be valid- they purport o be such that if the premises are true then the conclsuion will certainly be true- a deductive argument fails if it is invalid.
Inductive arguments
They do not purport to be valid. i.e. use the word ‘probably’ i.e. the whiteness of swans
Ennumerative induction
This purports to ground a generalisation, a universal claim i..e all swans are white’, based on a number os supporting premesis.
Validity
this is a necessary but not sufficent condition for a good deductive argument
Can be valid even if only one premise is false and the conclsuion still true, however if one premise is false thent he argument fails to show the conclsuion is true
sound
a valid argument where all premises are true. It may be a pointless argument but it could easily be valid and sound
Rights
positions we hold in relation to others
I have a duty no to assult Ben
this is a duty of negative content- an omission
Multital right
when the class of duty holders is indefinate
Paucital right
when the class of duty holders is definite
Unital right
a unique right against a single person
A negation of a legal position is in itself a legal position
i.e. It is not the case that audrey has towards ben a duty to pay ben £40
She wasn’t rich or poor
Propositions are contrary when they both cannot be true
They are also not jointly exhaustive ie. both can be false
contradictory terms
they are mutually exclusive and jointly exhaustive
Contradict of;
duty to do somthing
A liberty not to do it
correlative of a liberty not to do something
a no- right
All rights;
concern an action or ommission by a duty holder
Dilemma
P or Q
If P then R
If Q then S
Therefore R or S
OR
P or Q
If P then R
If Q then R
Therefore R
Reductio ad absurdum
The assumption that S is false will lead to a contradiction or a claim that is absurd or false. Therefore S must be true
Fallacy of appealing to ignorance
‘we have no evidence showing he is guilty so he must eb innocent’
Ad hominem fallacy
Theory disregarded not due to lack of evidence but due to person arguing for it
Contradiction of;
Right
No Right
Contradiction of;
Privilage (liberty)
Duty
Contradiction of;
Power
Disability
Contradiction of;
Immunity
Liability
Correlative of;
Right
Duty
Correlative of;
Privilage ( liberty)
No right
Correlative of;
Power
Liability
Correlative of;
Immunity
Disability
Right
Every right is a relation between no more than two people.
in personam rights- attached to specific person i.e. in a contract
in rem rights- property rights enforceable against the entire world.
‘right not to be tortured by someone’
this is not a hohfeldien right because no-one else is under a CORRELATIVE DUTY TO ABSTAIN FROM TORTURE
Liberty (privilage)
This is an absense of a duty to abstain from an action
It is a weaker right i.e. ‘I have a right to smoke in your vicinity’ - THIS IS NOT true as theere is an absense of a correlative duty. Instead you have a LIBERTY to smoke in the vicinity.
A liberty attracts the corelative ‘no right’
Power
Ones ability to alter legal relations.
‘I have the power to enter into a contract with S whereby he agrees to stop smoking’
S thus has a liability (co-relative) in that he is liable to having his legal relations changed by the excersise of my power
Immunity
If X has an immunity against Y it means that Y has no power to change X’s legal position in regard to any entitledments covered by the immunity.
i.e. if the state has no power to place me under a duty to wear a hat when I go out then I have an immunity in that respect and the state has a disability (co- relative)
antithesis
it is the opposite of something i.e. love is the antithesis of selfishness
asserting the conditional
If the antecedent is true as well
converse
if Q then P
Inverse
It is not the case that P therefore it is not the case that Q
contrapositive
It is not the case that P therfore it is not the case that Q
Bioconditional
P and only if P then Q
analogy
similar aspects and the two cases are unrelated but are governed by the same principles.
you reach the same conclsuion but for different facts
abudtive
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