Inductive reasoning and deductive reasoning represent two polar approaches to critical reasoning. But what is the difference between inductive and deductive reasoning? We’re going to break down inductive vs deductive reasoning by looking at examples from Meet the Parents, 12 Angry Men, and more. By the end, you’ll know how inductive and deductive reasoning are used, and how to implement them in your own writing.
How to Tell Inductive from Deductive
Background on critical reasoning
Deductive reasoning is a top-to-bottom approach which stipulates that defined premises must add up to a true conclusion. What are “premises?” Premises are components of an argument.
For example, if the premises state:
All good dogs follow their owner.
My dog is a good dog.
Then the logical conclusion would be:
Therefore, my dog will follow me.
This deduction is logically sound. What does “sound” mean? Soundness, in a philosophical sense, is proof that an argument is both logically valid and its premises are true. If the conclusion is proven false, then the deduction will be logically unsound.
For example, if my dog doesn’t follow me, then either the premise “all good dogs follow their owner” or “my dog is a good dog” has to be unfounded. In such a case, researchers must adjust the premises and conclusion, or abandon the hypothesis altogether.
Conversely, inductive reasoning is a bottom-to-top approach which stipulates that specific observations can be used to draw general principles.
For example, if the observation is:
The home team has won every game I have attended.
Then the logical induction would be:
The home team will win the next game I attend.
This induction is known as predictive because it predicts the likeliness of a future event based on past data. Predictive inductions are just one type of inductive reasoning; there are many more.
But before we get too far ahead of ourselves, let’s check out a great video on the basics of inductive vs deductive reasoning.
Inductive and deductive reasoning may sound like difficult concepts to understand – but they’re actually very simple. Of course, the intricacies of the subtypes can get tricky; I find myself getting tricked up from time to time. But just remember: deductive reasoning is a top-to-bottom approach and inductive reasoning is bottom-to-top approach.
So, without further ado, let’s define inductive reasoning.
INDUCTIVE REASONING DEFINITION
What is inductive reasoning?
Inductive reasoning is a “bottom-up” process of making generalized assumptions based on specific premises. Inductions are usually made at a subconscious level, but they play an integral role in our actions and beliefs. For example, an induction could state that everybody at a party was wearing blue shirts, Laura was at the party, therefore she was wearing a blue shirt.
Characteristics of Inductive Reasoning:
- Bottom-to-top reasoning
- Effective for world building
- Predictive, not certain
Inductive reasoning is an exercise in generalization; AKA taking specific observations and generalizing into greater truths. This video takes a quick look at the difference between deductive and inductive reasoning.
Inductive reasoning is a probability metric. Deductive reasoning is a certainty metric. Now let’s define deductive reasoning.
DEDUCTIVE REASONING DEFINITION
What is deductive reasoning?
Deductive reasoning is a “top-down” process of understanding whether or not an assumption is true, based on logic and experimentation. Deductions begin with a general assumption, then shrink in scope until a specific determination is made. For example, a general assumption may state that all dogs have eyes; this is a logical premise, but I could argue that I have eyes, therefore I must be a dog, which would prove the deduction to be illogical.
Characteristics of Deductive Reasoning:
- Top-to-bottom reasoning
- Effective for reaching certain conclusions
- Not a “foolproof” method
What Does Inductive and Deductive Mean?
Inductive reasoning examples
Inductive logic dictates that specific experiences can be used to induce conclusions. So, what does this process actually look like?
For an answer to that question, check out this clip from Meet the Parents:
Let’s break down the inductive reasoning in this scene. Here, Greg (Ben Stiller) expresses distrust in the airline’s ability to transport his bag. Why? Because the airline previously lost his bag. Thus, he concludes that it’s likely the airline will lose his bag again.
“Your airline sucks at transporting bags. Because I already did that once and you lost it. And then I had everything screwed up very badly… how do you know my bag will be safe below with all the other luggage? Are you physically going to take my bag and put it beneath the plane?”
— Ben Stiller in Meet the Parents
It may sound silly to say, but this example from Meet the Parents really is a great example of inductive reasoning.
Now, let’s break down some different types of inductive reasoning!
Take a specific observation and make a generalized conclusion.
Example: “There was a home run in the last baseball game. Therefore, there will probably be a home run in the next baseball game.”
Statistical inductions take data into account to give a more accurate prediction.
Example: “There has been a home run in seven out of the last ten baseball games. So, there’s a 70% chance there will be a home run in the next game.
Bayesian inferences add circumstantial information to statistical data.
Example: “I’ve only ever seen baseball games at one stadium, so my data may not accurately reflect the whole league.
This is when you take a generalization about a group and apply it to an individual.
Example: “All the players who have hit home runs have been outfielders, so the next home run hitter will be an outfielder too.”
Comparing two things with a shared quality and inducing that they must have another shared quality too.
Example: “Your favorite player hit a home run. My favorite player hit a home run. Therefore, your favorite player and my favorite player are the same player.
6. Causal Inference
When you infer a correlation between two causal events.
Example: “I only see players hit home runs during night games. I suspect I’ll see a home run tonight since I’m going to a night game.”
Inductive reasoning is used all the time in everyday life. Next time you think about a “foregone conclusion,” consider how that perspective developed – what observations or experiences made you think that way? And how can you improve your inductive reasoning to better reflect the complex nature of critical thought?
How is Deductive Reasoning Different from Inductive Reasoning?
Deductive reasoning examples
Deductive logic dictates that assumptions can be proven true or false by matching the veracity of premises to a conclusion. But what does “the matching of premises to a conclusion” look like in practice?
Well, one good example can be found in the 12 Angry Men screenplay. We imported the 12 Angry Men screenplay into StudioBinder’s screenwriting software to take a look at deductive reasoning in writing.
The law of the United States of America states that “the Due Process Clause protects the accused against conviction except upon proof beyond a reasonable doubt of every fact necessary to constitute the crime with which he is charged.” In criminal cases, deductive reasoning is used by the prosecution to “build a case” against the defendant. It is the onus of prosecutors to argue that certain premises add up to a conclusion that proves the defendant’s guilt.
In 12 Angry Men, the prosecutors argue that evidence and witness testimonies (premises) prove the conclusion that the defendant murdered his father. The jury is tasked with deciding whether the prosecution’s deductive reasoning is sound; or in other words, that the defendant can be proved guilty beyond any reasonable doubt.
In the end, spoilers beware, the jury decides that the prosecution’s deductive reasoning is unsound. Several of the prosecution’s premises are proven to be not-valid, thus rendering the conclusion false.
Now, let’s break down some different types of deductive reasoning!
Syllogism is probably the most simple of the 3 types of deductive reasoning. In simplest terms syllogism states that if A=B and B=C, then A=C. It takes two separate clauses and connects them together.
Example: carrots are vegetables, vegetables are plants, therefore carrots are plants.
2. Modus Ponens
A modus ponens is when a deduction is presented as a conditional statement, proven by subsequent clauses: the antecedent and consequent.
Example: every person in my group has brown hair. Carlos is in my group, therefore he must have brown hair.
3. Modus Tollens
A modus tollens is the opposite of a modus ponens. Whereas the latter affirms a conditional statement, the former refutes it. For example:
The boiling point of water is 212 degrees Fahrenheit. The water is colder than 212 degrees Fahrenheit, therefore it will not boil.
Inductive and deductive reasoning may be two polar strategies to critical reasoning – but they’re both incredibly useful.
What is an Allegory?
Want to learn more about how philosophical principles are used in writing? Check out our next article on the art of allegories in which we break down examples from Snowpiercer, Fight Club, and more. By the end, you’ll know what an allegory is and how it’s used in film/literature.