In Lesson 5, students are asked to create a logical argument to support their Big Goal. Creating an argument is generally though of as being easy, but creating one that follows correct logic can be more challenging. With this in mind, we’d like to help explain how a logical argument is crafted and the three stages a logical argument must follow.
What’s a logical argument?
Logic is the science of reasoning, proof, thinking, or inference. Logic lets us examine a piece of reasoning, or a thought, and determine whether it is correct or not.
The building blocks of a logical argument are propositions, also called statements. A proposition is a statement which is either true or false. For example,
“Washington D.C. is the capital of the United States.”
An argument is a connected series of statements that create a logical, clear, and defined statement. There are three stages to creating a logical argument: Premise, inference, and conclusion.
Stage one: Premise
The premise defines the evidence, or the reasons, that exist for proving your statement. Premises often start with words like “because”, “since”, “obviously” and so on.
Stage two: Inference
In this stage, we take one or more statements that are agreed upon as true and come up with a new statement. This new statement often uses the words “implies”, “suggests” or “therefore”.
Stage three: Conclusion
The conclusion of an argument is a final statement. The conclusion is often stated as the final stage of inference. It’s validity, or truth, is confirmed by the truth of the premises statement(s) and the inference statement(s). Conclusions use words like “therefore”, “it follows that”, and “in conclusion”.
A Logical Argument Example:
Premise Statements:
“Washington D.C. is the capital of the United States.”
“The President of the United States lives in the White House.”
“The White House is at 1600 Pennsylvania Avenue, Washington D.C.”
Inference Statement(s):
“These statements imply that the White House is located in Washington D.C.”
“These statements also imply that the President lives in Washington D.C. by living in the White House.”
Conclusion Statement:
“Therefore, the President of the United States lives in the capital of the United States.”
With help from “Constructing a Logical Argument” available at: http://www.virtualschool.edu/mon/SocialConstruction/Logic.html
For another method for creating a logical argument, check out this link:
Building Logical Arguments
You can also download this handy guide from Purdue University’s Online Writing Lab:
Logic in Arugmentative Writing