Critical Thinking and Arguments
Critical thinking is about having sufficient epistemic reasons for our beliefs and decisions.
Whenever we have reasons for our beliefs, we can formulate them into an argument.
Doing this makes it easier to tell whether our reasons are sufficient.
In this chapter, we will study some methods for organizing our reasons into an argument and then
telling whether they are sufficient.
An argument is a set of statement one of which (the conclusion) is taken to be supported by the
remaining statements (the premises)
Here’s another way of saying this:
An argument is a group of statements in which some (the premises) are inended to support
another (the conclusion)
The conclusion is what the speaker wants you to accept or believe
The premises state the reasons or evidence for accepting the conclusion
First, break it down into all of its assertions. For example “The restaurant was terrible. For the food was
cold, and the service was slow and the tables were dirty”
1. The restaurant was terrible
2. The food was cold
3. The service was slow
4. The tables were dirty
The word “for” was left out since its not really part of the assertion, well come back to his later. I
analyzed the conjunction into its conjuncts, ALWAYS DO THAT. NEVER analyse conditionals or
disjunctions into their parts (Leave “if-then” and “either-or” claims in that form)
How to recognize arguments:
Look for a conclusion (a statement that is being supported), and look for premises.
Ask: is the author trying to get me to believe something by giving me reasons in support of it? If
yes, it is probably an argument. If no, then it’s probably not an argument Look for indicator words
It follows that
We may conclude
Premise – Indicators
In as much as
For the reason that
The “Therefore” Test
If there are no indicators, you could try inserting one between the assertions to see which makes most
“We should not build a bridge. It would be too expensive”
(1) We should not build a bridge
(2) Building a bridge would be too expensive
Which makes more sense? (1) Therefore (2), or (2) therefore (1). Section 3.3 – Independent and Dependent Reasons
Critical thinking is about having reasons for our beliefs and decisions. Sometimes, we can have many
different reasons to believe something or to do something, and sometimes our reasons are complex
“I probably shouldn’t go to the bar tonight. I should study for my SSH105 quiz, and I’m basically broke
(1) I probably shouldn’t go to the bar tonight
(2) I should study for my SSH105 Quiz
(3) I’m basically broke anyway
These premises are independent: each would provide support for the conclusion even if the other
premise was false.
“Tom is a police officer and all police officers love donuts. So Tom loves donuts.”
(1) Tom is a police officer
(2) All police officers love donuts
So, (3) Tom loves donuts
When you see the word so, you know for a fact that what comes next is a conclusion.
These premises are dependent: neither would provide any support for the conclusion if the other
premise was false.
Two test for dependent premise:
The Word Test: if some important words in the conclusion only occur in one premise and other
important words from the conclusion only occur in the other premise, then the premises are probably
Aristotle is a man, and all men are mortal, so Aristotle is mortal.
You need the ideas from both premises to get all of the ideas in the conclusion. So they are dependent.
The False Premise Test: if a premise would provide reason to accept the conclusion, even if the other
premises were false, then the premises are independent.
“Bill robbed the bank and murdered his mom. Bill is obviously a criminal.”
(1) Bill robbed a bank
(2) Bill murdered his mom
(3) Bill is obviously a criminal
Either premise on its own, even if the other one was false, would be reason to accept the conclusion. So
they are independent. Circumstantial Reasons
Sometimes, apparently independent premises are actually meant to be working together in a
piling-on sort of way
o John is the robber. He was in the bank at the time. He owns a gun like the one used in
the crime. The money from the crime was found in his building. And he has a record of
Even though each bit of evidence on its own is not very strong, when piled up together it makes
a strong case
But these cases always involve a missing premise. The author is leaving out an additional
premise, will be defined later on
A sub-argument is an argument supporting one of the premises in an argument. In usch a case,
one statement is playing two roles: a premise in the main argument, and also a conclusion of the
o “You should not give Edward an allowance because he never does any work around the
house, and he will probably just waste it since he has no conception of the value of
1. You shouldn’t give Edward an allowance
2. BECAUSE Edward never does any work around the house
3. Edward will probably just waste it
4. SINCE Edward has no conception of value.
In this argument, (2) and (3) are independent premise. Statement (4) is offered as a reason for
believing statement (3).