PHL145H5 Chapter Notes - Chapter 2: Raw Image Format, Institute For Operations Research And The Management Sciences
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Chapter 2 Textbook Notes
2.1.1: Inferences & Arguments
The process of making judgement or assumptions based on something is
making an inference.
An argument is described as a group of sentences.
One sentence being the conclusion.
All of the other sentences are the premises.
An argument is done by using the premises to support and justify the claim.
A good argument is one in which the premises provide the receivers to good
reason to believe the other person’s claim is true.
Arguments consist of either declarative or indicative statements, rather than
commands or questions.
The person making the argument is often trying persuade the receiver to
view things their way.
In terms of critical reasoning, it is best to simply view arguments as a collection
One being the claim, the remaining statements being the premises that
are used to justify and support the claim.
E.g. If the results of a poll, state that 87% of people surveyed in the poll will vote
for Republicans. One might the Republican candidate will win the election.
The assumption that the Republican candidate will win the election based
on the results of the poll is the inference.
Important, remember that inferences are a process, not the end
The results of the poll in this case would be the premise.
The reason for believing that the Republican candidate will win the
The Republican candidate will win the election, this is the claim or
2.2: Uses of Arguments
Often times, we try to determine the what would the outcome would be if we did
something, this process is called reasoning.
E.g. If you have a budget of $50, how much would would you have remaining for
other expenses if you spent $25 on dinner.
E.g. If you get a certain mark in a course, how much will your GPA rise?
We frequently make arguments where we are attempting to convince someone
to believe in what we believe in, this is called persuasion.
It involves making a deﬁnite claim and trying to persuade someone to believe
your claim is true, by giving them the reasons as to why they should believe.
E.g. Religious leaders
Sometimes we need to evaluate someone’s argument to determine if their claim
To do this, we must verify if their premises justify their conclusion.
If not, we should be able to verify where the problem lies, what premises
are valid and which are not.
2.3: Identifying Arguments In Their Natural Habit
The ﬁrst step you should always take when determining whether something you hear
or read is an argument is to search for a conclusion, if one exists.
If one exists, it is usually very simple to determine the premises.
Therefore, ﬁrst step should always be to ﬁnd a conclusion, if one does exist.
2.3.1: Indicator Words
Conclusion indicators are words that indicate the conclusion will be coming up
E.g. Mike is taller than me, therefore Mike is tall.
Therefore is a conclusion indicator as it informs us that the
conclusion should be following this word.
Examples of conclusion indicators include:
therefore, hence, thus, in conclusion, consequently, etc.
Conclusion indicators usually indicate the conclusion will come at the end
of an argument.
There are also premise indicators which introduce a premise.
E.g. Mike is tall, because he is taller than me.
Because is the premise indicator.
Examples of premise indicators include:
because, for, since, after all, in view of the fact, here are the
Premise indicators usually indicate the conclusion will be at the beginning
of an argument and the premises will follow.
Very crucial, in real life things are not as easy to spot, always use your
Sometimes, premises are missing in an argument because the premises
are believed to be common knowledge and does not require restating.
Other times, the conclusion is omitted, because the person arguing feels
that the premises have made it clear what the conclusion is and that it
would be insulting to you to explicitly state the conclusion.
The rules above are guidelines, but there are always exceptions. Always
trust your judgement ﬁrst and foremost.
2.4: Putting Arguments Into Standard Form
Rarely, do arguments come neatly in Standard form, so we need to be able to alter the