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8 Examples of Logical Arguments

John Spacey, June 05, 2019

A logical argument is the use of informal logic in a natural language to support a claim or conclusion. This should not be viewed as a magical path to truth and validity as logic can suffer from problems such as invalid data, disputable premises, fallacies and neglect of grey areas. The following are illustrative examples of a logical argument.

Practical

Practical logic is based on three components: claim, grounds and warrant. A claim is your conclusion, grounds are supporting evidence and a warrant shows how the evidence maps to the claim.

Claim: Tokyo is rainy.
Grounds:: London is considered rainy.
Grounds:: Tokyo gets 1,530 millimeters of rain a year.
Grounds: London gets 584 millimeters of rain a year.
Warrant: Average annual rainfall is a strong indicator of whether a city is rainy.

Premises

Any facts, assertions, probabilities or data inserted into an argument can be viewed as a logical premise that makes your argument somewhat logical. This often takes the form of "conclusion because premise."

They were a bad employer because they didn't treat the customer with respect.

Deductive

Deducing your conclusion from a set of premises using deductive reasoning.

A: Toronto is in Canada
B: Alice lives in Toronto
C: Alice lives in Canada

Inductive

Suggesting a probable conclusion based on the probability of premises.

A: Most Canadians like Hockey
B: Alice is Canadian
Conclusion: Alice probably likes hockey

Extrapolation

Estimating the future based on current or historical observations.

Premise: The economy has faced dozens of recessions and recovered each time.
Conclusion: The economy will recover again.

Analogy

Analogy, particularly metaphors, can be used to construct complex inductive arguments by suggesting that two entities are essentially the same in some way.

Premise (metaphor): The Earth is a living organism.
Premise: Organisms can become ill and die.
Conclusion: The Earth can become ill and die.

Cold Logic

Cold logic is a logical argument that neglects human society, culture, values and emotion. This isn't likely to get you anywhere with people.

Premise: Cats consume resources such as food.
Premise: Cats do not contribute to economic production.
Premise: It is a waste to spend resources without creating economic value.
Conclusion: Cats are a waste of resources.

Fallacy

Fallacies are flaws in logic. These can be complex and difficult to detect. As such, most of the work of having a logical conversation or constructing a logical argument is vetting logic for fallacies.

A: Our AI detected that Eric was cheating on the test.
B: Our AI scanned 1 million students.
C: Only one student was actually cheating.
D: Our AI has a 1% false positive rate.
Conclusion: There is only a 1% chance Eric is innocent.

The above conclusion suffers from the Prosecutor's Fallacy. The AI scanned 1 million students with a 1% false positive rate. This means that 10,000 students were falsely identified as cheaters. Only one student actually cheated so that means there is a 9,999:1 chance that Eric is innocent or 99.99%.