This is part 1 of PHI1025F:
"The aim of this course is to help you develop your skills as a critical
thinker. All of us hold certain claims as true and others as false; we think some courses of
action are right and others are wrong. Often we cite reasons for our beliefs and actions. Critical
thinki...
Critical Thinking
Human thought is far more biased and irrational than we assume. We often form beliefs based more
on emotions than reason.
Critical thinking = systematic evaluation or formulation of beliefs according to rational standards
- Systematic because distinct methods are used
- Beliefs are evaluated/assessed, and new ones are devised/formulated
- Beliefs are evaluated by how well they’re supported by reasons (rational justifications)
Argument
= an attempt to support, justify or defend a conclusion/belief by providing reasons for it.
A bad argument is when the premises fail to support the conclusion (but it’s still an argument)
Need to be well-supported by the reasons
- Not a fight: not personal
- The purpose is to convince others through rational reasons
Arguments consist of two parts: the conclusion/claim and
reasons/premises
1: Conclusion/claim
What is being argued for / the belief being supported
2: Premise(s)
= reason(s) intended to support the conclusion/belief
Each reason is called a premise. An argument will contain at least one premise
They’re what matter the most. They need to be acceptable to everyone (not subjective)
A bad argument is one where the premises fail to support the conclusion; a good argument is one
where the premises provides grounds for believing the conclusion to be true
Statements
= A proposition that expresses a truth value. A claim that can be assessed as true or false.
Examples: “the earth is flat” or “the earth is round”.
Conclusions and premises are expressed as statements. An argument itself is not a statement
though.
,Note that rhetorical questions can also be statements. They’re like “statements in disguise”, the
statement is implied. E.g. “Haven’t we had enough letters to the editorial page from cry-baby steel
workers?”
Commands and exclamations can also express statements in special contexts. So be mindful of
context. E.g. “You’d better study or you’ll fail!”
You don’t need to know whether it’s true or false to know that it’s a statement e.g. “the number of
stars in the universe is even”
Statements are written or spoken as sentences. However, not all sentences express statements.
Examples of sentences that express statements: “7 + 5 = 12.”; “A triangle has 3000 sides.”; “You are
a liar.”; “You are not a liar.”
- These are all considered statements because they have a truth value
Sentences that do not express statements: “Leave me alone.”; “How are you?”
- These aren’t statements because they’re neither true nor false
Assumption of Bi-valence (ABV):
= a statement always has a truth value. They can be true or false, but never both at the same time.
- ABV says that every statement has exactly one of two truth-values (truth or falsehood), and
there’s no third truth-value
- It also allows for statements with unknown truth-values
It is possible to express the same statement and truth value in different words.
- For example, the sentence (1) “Obama was not born in Kenya” as uttered by me expresses
the same statement as (2) “I was not born in Kenya” when it is uttered by Obama.
Statements are true or false, whereas arguments are valid or invalid
Identifying arguments
How do you tell the difference between an argument and a statement?
- An argument has a premise or premises that aim to justify a conclusion, whereas an
unsupported statement is simply a claim/proposition by itself
When trying to spot an argument, it helps to first pick out the conclusion (as there is usually only
one)
- The conclusion can come before OR after the premise(s)
- There should also be premises: if there aren’t premises present, it’s not actually an
argument
Look out for the conclusion and proposition indicators:
- Conclusion indicators: “therefore, so, thus, consequently, it follows that”
- Premise indicators: “since, as, given that, because”
, These questions can help you differentiate between premises and conclusions:
What is the author assuming or taking for granted? (Premises)
What is she trying to persuade her readers or audience to accept? (Conclusion)
What may be seen to support (or be understood as a reason for believing) something?
(Premises)
What statement may be seen as supported by (or advanced on the strength of) the rest of
the argument? (Conclusion)
Be wary of explanations and causal links: they are not arguments as they’re not trying to prove (or
convince you of) anything, they’re simply stating a fact. They don’t have premises trying to justify a
conclusion.
Examples
“Sammy must be afraid of spiders. He ran out of the room when the spider appeared on the wall.”
This is an argument. The conclusion being supported is that “Sammy is afraid of spiders.”
There are no indicator words which make it easy to locate the premises and conclusion. But
still, there is clearly an attempt to prove that Sammy is afraid of spiders based on the fact
that he ran out of the rom.
“Sammy is afraid of spiders. He was bitten by one as a child.”
This is not an argument, but rather an explanation. It does not try and convince us that
Sammy is afraid of spiders but rather explains why it is the case.
A note on relativism
Philosophers are generally sceptical of the idea of a subjective/relative truth (“what’s true for me
isn’t necessarily true for you” / “there is no wrong or right opinion”)
If relativism were true, then even the most absurd-sounding beliefs must be true. If someone
sincerely believes that all other people are mindreading aliens out to destroy him, then he is correct!
Relativism is also self-refuting: If everything is just an opinion, which we have no reason to think is
right or wrong, then so is the claim that everything is just an opinion! So we have no reason to
believe that.
Deductive & Inductive Arguments
When formulating arguments, you must make sure the beliefs are justified; when evaluating
arguments, you must make sure not to accept beliefs based on bad arguments
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