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Chapter 3: Writing Mechanics Help
Chapter 12: Teaching Writing
Chapter 23: Teaching Reading
College English Composition: Help and Review
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Reasoning in Essays

You know that feeling you get when the murderer is revealed at the end of a murder mystery, and everything suddenly makes sense? It’s that feeling when all the clues fit right into place, and you have that ‘aha’ moment.

On the other hand, have you ever read or seen a mystery where the ending seems to come out of nowhere, and it seems that the author just made up the solution at the last minute? Mystery fans may not want the clues to be overly clear and obvious, but at the same time, those fans want there to be some sense and logic to how everything is resolved.

Student essays should have the same type of sensible, logical structure. The reader should be able to track the writer’s reasoning to see how the writer got from point A to point B. In this video, we’ll think about deduction and induction as ways that writers can structure their reasoning in argumentative essays.

Deductive Reasoning

We often judge a persuasive essay by how effective the writer is at convincing us of his or her main argumentative point. There are a few ways that a writer can go about trying to convince his or her readers, and there are different ways that argumentative points can be ordered.

Deductive reasoning entails starting with a generalization and moving to specific details. Here’s a short example of a paragraph that uses deductive reasoning:

Our state must require high school seniors to pass an exit exam before graduating. Many recent high school graduates in our state cannot land jobs because they don’t have adequate reading and writing skills. A high percentage of today’s high school seniors have below-grade-level math skills, which will make it difficult for them to hold many jobs or succeed in college courses.

Notice that this short paragraph starts with a general topic sentence that sets forth a broad argument, and then proceeds to specific details that offer support for the main idea. This deductive pattern is quite common, especially in student essays. Teachers often want students to start out with a clear thesis at the start of an essay and with clear topic sentences at the start of each paragraph. By following this pattern, students can show that they know how to craft a clear main idea, and then support and develop that idea.

Inductive Reasoning

The opposite of deductive reasoning is inductive reasoning, which involves starting with specific details and moving to a larger concluding point or generalization. This short paragraph provides an example of inductive reasoning:

Many college students use laptop computers during class. While some students use their computers to take notes and look up facts related to course discussions, many others use computers to compose emails that aren’t related to class, play games, and surf the Internet. Laptop computers must be banned from college classrooms in order to minimize distractions for students.

The writer of the paragraph has arrived at the conclusion by working through specific details and then arriving at the main point.

Evaluating Reasoning

As I noted earlier, a deductive pattern occurs more often than an inductive pattern because deduction involves starting with a topic sentence or main idea and then providing specific support. This more closely matches the general pattern that teachers often look for in student papers.

It’s still useful to be familiar with each type of pattern and to understand how main points are supported and reached. Additionally, being able to evaluate an essay for the strength of its reasoning is a good skill to have. You may sometimes be called upon to critique an essay that you’ve read, and being able to take apart and evaluate something you read can be helpful as you build your own writing skills, too.

When assessing the effectiveness of a piece of deductive reasoning, for example, you should determine first whether there is a clearly expressed main point, which would typically be expressed in a thesis statement at the start (or in a topic sentence if you were looking at a short example like our sample paragraphs from earlier). With deductive reasoning, in addition to offering supporting details after the generalized main idea, the writer will often try to apply the general statement at the start to the specific statements that follow. For example:

In towns where I have lived that have many nice playgrounds, the children are healthier and more active. I have just moved with my child to the town of Grace Point, which has several playgrounds, so I can expect him to be healthy and active.

Consider whether the writer has moved from the general to the specific here. The answer is yes, because the first statement is about towns with lots of nice playgrounds, and the resulting impact on the kids in the area. In the next statement, the writer has applied that first general statement to a specific situation about the writer’s own town and own child. So, these statements follow a familiar pattern.

Do you think that this is the most airtight argument, though? Is there a flaw in the writer’s reasoning? As you evaluate the reasoning in a paragraph or essay that you read, think about what might be left out in the writer’s chain of logic. We know that the town of Grace Point has many playgrounds, but that doesn’t automatically lead to a situation in which the writer’s child will be active and healthy. If that were the case, we could all be in great shape just by living near a gym, without ever having to go in!

As readers, we would first need to see evidence that the healthy kids in other towns are healthy because they use the playgrounds. We’d also need to see evidence that the writer’s child uses the playgrounds in Grace Point regularly and that the specific playgrounds in question are good ones that offer plenty of space to run around and equipment that helps give the kids who visit them good workouts. Developing your skills for spotting problems in the reasoning patterns that you read can help you as you work to avoid the same type of problems in your own writing.

Lesson Summary

It’s important for readers to be able to make sense of how a writer has gotten from point A to point B in an argument. When a conclusion seems to come from nowhere, the reader will be confused rather than convinced.

It’s useful to be familiar with basic reasoning patterns and to be able to spot holes in logic. Remember that deductive reasoning entails starting with a generalization and moving to specific details, and inductive reasoning involves starting with specific details and moving to a larger concluding point or generalization.

As you analyze a piece of writing, consider whether the writer has left out crucial evidence in support of his or her points. Reviewing and critiquing the reasoning of others will help you build your own reasoning skills.

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