Analytical thinking & Critical reasoning notes

Analytical thinking & critical
reasoning




Whati s an
argument?


3
1. A set ofpremisis
2. conclusion.
A
Signal words make easier to


distinguish

A
sentence is
any declarativ Statement

thatmakes a claim about
something

deductiv
arguments


!
inductiv
arguments
↓ x

Valitity & soundness

6 the conclusion is impossible to be false,
because all premises are true

varia
argument
=>




a deductive
argument is sound ifit's valid &
the
premises are all in
fact true

, logical possibility the
argumentation
matching to the
as to be coherent
conclusion
I
coherently valid
can't
imagine
-




-



can
imagine
=
invalid

Varid doesn'tmean "true premises" or"true
conclusion"

1. All cats are mammals. -> Invalid because John
2. All mammals are alive. is not
part of the premises
John alive premises &
. . is the conclusion


are not coherent

1. All cats are mammals-> varia

2. All mammals are alive

3.John is a cat/mamme

.
:
John is alive.



&
*
C 07.09.2




The vocabulary ofL

1. Capital letters A, B, C.... to representatomic sentences

2. Symbols for truth-functional connectives:

· ~

representing negation ("not"
#
·




rep conjunction land" only true if both XY are true



vrep. disjunction"or") only false ifboth ydy false
·


are



· ->
rep. Conditional ("if-then"/ only false ifthe consequence; is

false & if dy are false it's true
·



rep, biconditional ("ifand onlyif" yy are either both true

to be true
or both false