1. Constructing a Logical Argument

2. Constructing a Logical Argument
To construct a logical argument, you have two principal patterns available to you—

3. Constructing a Logical Argument
Inductive Reasoning
and
Deductive Reasoning

4. Constructing a Logical Argument
Inductive reasoning involves collecting “proofs”.
From these, the reader is asked to make an “inductive leap”.

5. Constructing a Logical Argument
Examples—
Jennifer leaves for school at 7:00 a.m. Jennifer is always on time. Jennifer assumes, then, that she will always be on time if she leaves at 7:00 a.m.
The chair in the living room is red. The chair in the dining room is red. The chair in the bedroom is red. All chairs in the house are red.

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Induction is often used by lawyers and detectives.

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Deduction works from a broad, general statement to particular examples.
It is also known as a syllogism.

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Major Premise – All humans are mortal.
Minor Premise – Socrates is human.
Conclusion – Socrates is mortal.

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All numbers ending in 0 or 5 are divisible by 5. The number 35 ends with a 5, so it is divisible by 5.
Red meat has iron in it and beef is red meat, so beef has iron in it.

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Be careful to avoid logical fallacies.
Constructing a Logical Argument

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The “Black-and-White” Fallacy
Example 1: “Either we go to war, or we appear weak.”
Example 2: “Either you love me, or you hate me.”

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Circular Argument 
When a person’s argument is just repeating what they already assumed beforehand, it’s not arriving at any new conclusion. We call this a circular argument or circular reasoning.

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Circular Argument –
“Abstract art isn’t even art. Those pictures and sculptures don’t represent anything, and that’s how you know its not even art.”

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Appeals to authority.
Constructing a Logical Argument

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Red Herring --
Constructing a Logical Argument

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Post Hoc Ergo Propter Hoc –

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