Critical Thinking ch3 Flashcards
propositions=
a set of premises advanced in support
of a conclusion.
an argument is a system of propositions
‘Sally is an artist, so she has some paintbrushes’, the arguer is probably using the rather vague term ‘artist’ in the narrow sense of ‘painter’. In the wider sense of ‘artist’ that includes sculptors and even actors and pop musicians, this would obviously be a bad argument. Furthermore, the arguer is assuming, without explicitly stating, that someone’s being a painter is reason to think they have paintbrushes. So two sorts of thing are left implicit in this argument: first, the arguer assumes a more precise meaning than is explicitly expressed
by the word ‘artist’; second, the arguer fails to make explicit all the facts from
which he or she infers the conclusion. A premise is left implicit.
oke
Argument-reconstruction is essentially a task of …
interpretation
principle of charity=
we moeten argumenten met de meest rationele persuasiveness voor de relevante audience reconstructen
If what matters to you is whether or not the conclusion of the person’s argument is true, then you should choose the best representation of the argument.
maar… natuurlijk niet te ver gaan.
deductive validity = synoniem
validity. dus validity is gewoon sowieso deductive
gaat over logisch
(deductive) validity=
if the premises are true, the conclusion must also be true.
andere interpretatie van deductive validity
it would be impossible for the premises to be true, but the conclusion false.
the concept of validity pertains to the connection between the possible truth-values premises and conclusion of an argument, not their actual truth-values considered individually.
oke
dus waar gaat validity over: hele argument of premises
over het gehele argument, de structuur
Thus, it should be clear that it would be nonsense to say of a single proposition
that it is valid.
oke
mogelijkheden voor valid arguments
1 The premises are all (actually) true, and the conclusion is (actually) true.
2 The premises are all (actually) false, and the conclusion is (actually) false.
3 The premises are all (actually) false, and the conclusion is (actually) true.
4 Some of the premises are (actually) true, some are (actually) false and the
conclusion is (actually) true.
5 Some of the premises are (actually) true, some are (actually) false and the
conclusion is (actually) false.
wanneer is een argument invalide
als de premises true zijn maar de conclusion is false
prescriptive claims =
desires, norms, moral rules.
you should, ought, need etc
descriptive claims =
factual
if its raining, then its cloudy.
wat is sufficient en wat is necessary
rain is a sufficient condition of clouds
clouds are a necessary condition of rain
- It is raining only if it is cloudy.
- Either it is cloudy, or it is not raining.
- It is not raining unless it is cloudy.
- If it is not cloudy, then it is not raining.
- It is not raining if it is not cloudy.
- It is cloudy if it is raining.
echt goed doornemen aub.
Either I sweat, or I don’t exercise
is goed!!!
want:
of p, of niet p en dan niet q
straw person/target =
This fallacy occurs when, in attempting to refute another person’s argument, you address only a weak or distorted version of it. Straw person is the misrepresentation of an opponent’s position or a competitor’s product to tout one’s own argument or product as superior.
John and Mary are having a heated debate about getting vaccinated. Mary argues that she doesn’t want to get vaccinated, because untested medical procedures involve taking a lot of risk, and therefore we should be careful about undergoing such procedures. John responds by first reconstructing Mary’s argument:
P1 Medical procedures are frightening
P2 Getting vaccinated is a medical procedure
P3 We should avoid all frightening stuff
———————————————————–
C We should avoid getting vaccinated
John then goes on to argue that Mary is wrong about not getting vaccinated, given that P3 is clearly not true.
What type of pseudoreasoning is John using to argue that Mary is wrong about not getting vaccinated?
A conditional is said to be true or false, rather than valid or invalid
oke
wat is het verschil tussen een conditional en een argument
- A conditional is one proposition that comprises two propositions as parts, joined by ‘if-then’ or a similar device. An argument cannot consist of just one proposition. It needs at least two.
- A conditional does not assert either its
antecedent or its consequent (dus, het is niet zeker). An argument asserts its premises and its conclusion.
dus conditional en argument in het voorbeeld van regen met cloud
conditional: If it is cloudy, then it is raining
argument: It is raining. Therefore, it is cloudy.
en wat dan in dit voorbeeld?
P1) If Labour does not change its platform, it will not attract new supporters.
P2) If Labour does not attract new supporters, it will lose the next election.
C) If Labour does not change its platform, then it will lose the next election
dit is een argument met een conditional conclusion en conditional premises.
wat is het verschil hierbij:
A P1) Susan is a marathon runner.
P2) Susan eats well and sleeps well.
C) Susan is healthy.
B P1) Willy is in the music club.
P2) No member of the music club plays jazz.
C) Willy does not play jazz.
bij A supporten de premises de conclusion individually.
bij B, neither premise supports C by itself, they need to be combined.
wat betekent het als een argument deductively sound is
To say that an argument is deductively sound is to say: the argument is valid,
and all its premises are (actually) true.
dus valid en premises are all true!!
waar staat P unless Q voor
if not Q, then P
dus dan wordt het diagram:
not q - p
P1) If P then Q.
P2) P.
C) Q
hoe heet deze argument vorm
modus ponens
P1) If P then Q.
P2) Not-Q.
C) Not-P.
hoe heet deze argument vorm
modus tollens
dus wat is modus ponens en wat is modus tollens
modus ponens = P -> Q, P dus Q
modus tollens = P -> Q, niet Q dus niet P
P1) P or Q.
P2) Not-P.
C) Q.
hoe heet deze argument vorm
disjunctive syllogism
P1) P or Q.
P2) If P then R.
P3) If Q then R.
C) R.
hoe heet deze argument vorm
argument by cases
P1) If P then Q.
P2) If Q then R.
P3) If R then S.
C) If P then S.
hoe heet deze argument vorm
chain
dus wat is het verschil tussen disjunctive syllogism en argument by cases
gaat beiden over P or Q.
DS: if not P = not Q, if not Q = not P
AC: if P then R, if Q then R. = R
¬ betekenis
not
wat is het verschil tussen
¬ P & Q
en
¬ (P & Q)
¬ P & Q -> P is niet true, Q wel
¬ (P & Q) -> P en Q kunnen niet beiden waar zijn
P1) All P are Q.
P2) All R are P.
C) All R are Q.
hoe heet deze argument vorm
categorical syllogism
P1) No P are Q.
P2) Some R are P.
C) Some R are not-Q.
hoe heet deze argument vorm
categorical syllogism
en deze is valid ja
P1) All P are Q.
P2) Some R are not-P.
C) Some R are not-Q.
hoe heet deze argument vorm
categorical syllogism.
deze is NIET valid.
oke regels van de venn diagram
grijs gekleurd is BESTAAT NIET
stippeltjes is at least some
de ‘all’ of ‘no’ premises moeten eerst!!
niet de conclusion in de diagram zetten, maar kijken of deze er uit komt.
goed kijken naar of er nog een mogelijkheid is. dan is hij valide als de conclusie deze zegt. als er meerdere zijn, is hij niet valide
P1) P or Q.
P2) Not-Q.
C) P
hoe heet deze argument vorm
disjunctive syllogism
P1) P or Q.
P2) Q.
C) not P
hoe heet deze argument vorm
dit is invalide!!!! want het kan ook beiden P en Q zijn.
dus deze vorm van disjunctive syllogism kan alleen als hij eindigt op P of Q. Niet niet-P of niet-Q
als je iets van all of only ziet, vaak invalid
okeee soms niet tho
hoe kan je not P -> unless Q omschrijven naar unless
P -> Q
if not Q, then P
hoe kan je P -> Q omschrijven naar either its… or its not …
P -> Q
either Q -> or not P
goed opletten als je … in de conclusion ziet!!
als je NOT in de conclusion ziet!! vaak kan er dan nog een andere mogelijkheid zijn die helemaal niet besproken wordt in de premises
hoe schrijf je only om naar not met P -> Q
only P -> Q
not Q -> not P
undistributed middle =
All Z is B
All Y is B
Therefore, all Y is Z
is een fallacy
