Let’s say you’re sitting in class, and you make any random claim like “Professor Smith never eats fast food” or “the neighbor’s dog is stealing my dog’s toys.”
Your friend might tell you to “prove it” or might ask, “How do you know?”
What your friend is actually wondering is what type of reasoning you used to make your claim and what evidence you can present to illustrate the validity of your claim.
The terms inductive and deductive reasoning might be pretty fuzzy in your mind right now. But you’ve probably used one of these types of reasoning to reach conclusions.
So what’s the difference between inductive and deductive reasoning, and how do you distinguish between the two if you’re asked to use one (or both) in a paper?
Here’s what you need to know.
What Is Reasoning?
In essence, reasoning is the process of logically and rationally thinking about something in order to draw a conclusion. That conclusion is based on the specific evidence you evaluate.
Depending on your assignment, you might use evidence from sources, evidence from personal research, or personal opinion and/or observations.
Remember, reasoning means you’re developing conclusions and making inferences. You’re not proving that something is true.
In other words, you can’t say that you’ve proved all gas stations sell pizza because you visited 10 gas stations and all 10 sold pizza by the slice.
Your observations might infer or suggest that all gas stations sell pizza, but they don’t prove it to be true.
Now that you know the basics, let’s talk about the two key types of reasoning: inductive and deductive reasoning.
Inductive and Deductive Reasoning Defined
Inductive reasoning
With inductive reasoning, you use facts, patterns, and other information to reach a conclusion. It uses specific examples to create a more generalized theory. It’s sometimes referred to as “bottom-up” logic.
This type of reasoning is more open-ended. It allows you to explore ideas and theories.
For example, let’s say that, during Monday’s lecture, Professor Smith mentions that fast food restaurants serve food that’s too high in sodium and fat. On Wednesday, he states that prices of fast food restaurants may be cheap (in some cases), but the food they serve is barely edible.
Let’s also say that this pattern continues on a somewhat regular basis. Throughout the semester, he makes negative comments about the nutritional value of fast food.
Based on his pattern of statements, you can use inductive reasoning to conclude that Professor Smith doesn’t eat at fast food restaurants.
You’ve used specific examples of your professor’s comments to infer a larger theory or premise about his behavior.
Keep in mind, though, that your conclusion might not always be valid. It’s perfectly acceptable to change your theory and/or reach new conclusions after you examine new evidence.
In this example, even though your professor made numerous negative comments about fast food restaurants, you might learn that he occasionally (or even frequently) eats at them.
Because your original conclusion is invalid, you might examine the evidence again to draw different conclusions.
In this case, you might look at the professor’s background and realize that he’s a nutrition expert. Thus, you might now conclude that he’s informing the class of the nutritional value of fast food meals. He’s not expressing a personal opinion or stating his personal dining preferences.
When to use inductive reasoning in an essay
When you’re using inductive reasoning, you’re presenting a conclusion based on specific facts, examples, or observations. (You don’t already have a theory in mind. You’re using evidence to help you develop that theory.)
You may choose to use inductive reasoning when writing a narrative essay, a work of fiction, or perhaps a persuasive essay.
Using inductive reasoning in these types of essays allows you to present information to keep the audience interested. Including evidence and examples along the way encourages readers to keep reading in order to learn about each part of the story and enjoy the journey as the tale unfolds.
You might also use inductive reasoning in social science classes.
Using inductive reasoning in essays, such as observation essays, allows you to observe patterns in behaviors and draw conclusions based on what you’ve witnessed or based on experiments you’ve conducted.
Inductive reasoning examples
Below are two examples of how you might use inductive reasoning in an observation essay.
Example #1:
You observe students’ dining preferences in the food court throughout the day. You notice that students who pay with a meal card consistently have trays overflowing with food, but students who pay in cash have consistently lesser amounts of food.
Based on the amounts of food students have on their trays and how they pay for their meals, you might use inductive reasoning to conclude that prepaid meal cards encourage students to spend more frivolously (and eat more food).
This may be because their parents have paid for the meal plan or because they swipe a card instead of paying with actual cash.
You might also conclude that students paying cash are using their own money and therefore must be more careful with how much they spend (and how much they can afford to eat).
Example #2:
You place a poster in a lounge in the freshman dorm encouraging students to volunteer at the local animal shelter. You place the same poster in the same area of a senior dorm.
Then you observe the area for several days and notice that more seniors than first-year students stop to read the poster. You also notice that more seniors take a photo of the poster in order to share the volunteer opportunity or to save the contact information.
Based on which group of students viewed and snapped pics of the poster more, you might use inductive reasoning to conclude that seniors are more likely than first-year students to volunteer. Or you might conclude that seniors are more likely than first-year students to be animal lovers.
In both of these examples, you’ve used inductive reasoning.
You’ve used the results of your observations to draw broader conclusions about student behavior. (You didn’t have a theory about student behavior before you began your observations. Instead, you developed your conclusions based on what you observed.)
Looking for an example of inductive reasoning in an essay? Read An Observation Essay About a Classmate.
Deductive reasoning
Deductive reasoning begins with a theory or hypothesis and then tests it to determine whether the theory is valid. It’s sometimes referred to as “top-down” reasoning.
This type of reasoning is more specific or narrowed as you’re testing or attempting to confirm a theory or hypothesis.
For example, you might begin with the hypothesis that the neighbor’s dog is wandering into your yard and stealing your dog’s favorite toys.
You’ve started with a general theory. Now you need to use deductive reasoning to test your theory to see whether it’s valid.
To test it, you buy a few new toys, let your dog play with them for a while, and then leave them in the yard. You watch the backyard all afternoon but don’t see any sign of the neighbor’s dog.
In the morning, the toys are gone. You revise your theory to state that the neighbor’s dog must be stealing the toys only at night.
To test your theory, you buy more toys, set up cameras, and check the footage in the morning. You realize that there is indeed a thief stealing your dog’s toys, but it’s not the neighbor’s dog. It’s a raccoon.
In this example, you’ve correctly used deductive reasoning but have determined that the original hypothesis is invalid.
Again, reasoning and testing theories don’t always mean you get the “right” answer each time.
When using deductive reasoning, you often have to test a variety of theories in order to reach a valid conclusion. (Ask any scientist. Most scientists will tell you all about deductive reasoning and creating test after test!)
When to use deductive reasoning in an essay
Deductive reasoning begins with a hypothesis, then tests and attempts to support that hypothesis.
If you’re thinking academic writing, a hypothesis of your paper might also be called a thesis statement. The evidence to support the hypothesis (or thesis statement) will be the evidence (like paraphrases, quotes, and summaries) from your research sources.
Thus, most academic essays—such as argumentative essays, compare and contrast essays, and literary analyses—will use deductive reasoning.
Scientific writing (like lab reports) will also use deductive reasoning.
Deductive reasoning examples
Below are two examples of how you might use deductive reasoning in an essay.
Example #1:
If your general hypothesis (or thesis) is that video games encourage aggressive behavior, you’ve started with a basic premise and need to provide evidence to support that premise.
You might use evidence from scholarly journals, credible websites, or interviews with experts, and use deductive reasoning to support your claim and develop your core arguments.
Example #2:
If you’re conducting a few culinary experiments, you might start with the premise that replacing water with cola when heating a can of condensed chicken noodle soup will create a mouth-watering culinary delight.
Based on your experiments of adding different types of colas to different brands of soup, you might use deductive reasoning to conclude that your original premise was invalid. Replacing water with cola does not make for a tasty soup.
In both of these examples, you’ve used deductive reasoning as you’ve started with a basic premise and used evidence (from sources or from your own experiments) to help reach conclusions.
Interested in reading an example of deductive reasoning in an essay? Check out The Importance of the Implementation of World Wide Immunization to Protect Our Children.
A Reason to Celebrate
Learning new stuff is always cause for celebration. But earning an awesome grade on your paper because you now understand the difference between inductive and deductive reasoning is even greater cause for celebration!
If you’re not quite ready to celebrate, though, and are looking for a few more tips and tricks to help you get that “A,” check out this useful essay advice:
- How to Write a Paragraph That Supports Your Thesis
- 12 Examples of Good Topic Sentences (and Why They Work)
- 10 Essay Writing Rules to Throw Out the Window
If you’d rather hold off on your celebrations until a professional editor has taken a look at your paper, send it our way.
