Use the letters P and C to label
the premises and conclusion of each
Titanium combines readily with oxygen,
nitrogen, and hydrogen, all of which have
an adverse effect on its mechanical
properties. As a result, tita
In categorical syllogism, we deal with terms
that are related by quantifiers and copula in
four different manners.
In propositional logic, we deal with
propositions as the basic units of meaning.
All complicated propositions or argu
Natural Deduction (1)
Besides using truth-table to prove the
validity of an argument, we can use another
method, called natural deduction, to do
Using this method, we can deduce step-bystep the conclusion from the premises with
the help of s
Exercises for Informal Fallacies
1. We should give an A to Tommy. It is
because if he does not get an A, it is likely
that he will not get enough GPA to be
admitted to HKU. You know, Tommys
parents are quite old and have high
expectation of him.
For a deductive argument, if all its premises are
true, its conclusion is necessarily true (or it is
logically impossible for the conclusion to be
I.e., the truth of premises guarantees the truth of
This is the foolproof way of determining the
truth-value of most compound statements.
The key is to know the truth tables for the 5
Translate into Symbolic Form
1. Passing the written exam is not a
A syllogism is a two-premise deductive
Or, a categorical syllogism is an argument
in which both the premises and the
conclusion are categorical propositions.
There are 3 propositions.
There are 3 terms.
Each term is used twice.
BASIC CONCEPTS OF
What is an Argument?
To justify or defend a claim is to give reasons or
arguments to support it.
Reasoning (or inference) is a psychological
When we express this process into words, we have
Argument Exemplar: Welfare and Social Justice.
There are significant omissions which are necessary in order to render the
Individualists optimism plausible. Either workers and businessmen would
have insurance of various kinds, or they would be insecure in
In daily life, we usually encounter
extended arguments such as those found
Our task is to sort out the arguments and
organize them in the simple form of a
1. Use numerals to label various
Formal Vs Informal Fallacies
A fallacy is a defect in an argument other
than its having false premises.
An informal fallacy is a defect in the
content of an argument. (A formal fallacy is
a defect in the structure of an argument.)