Sherlock Holmes (r) and Dr. John B. Watson. (Photo credit: Wikipedia)

In this post I am going to explain the difference between inductive and deductive writing and make the argument that, in most cases, writing that takes a deductive approach is superior for professional, academic, and public audiences.

You probably know that Sherlock Holmes used deduction to solve cases, but do you know what it means to write deductively? And what about inductive writing—the opposite of deductive writing?

In a nutshell, induction and deduction are logical approaches.

While induction focuses on details to arrive at a conclusion, deduction proposes a theory and then seeks out the specific details that support it.

Induction is a diagnostic approach often used by detectives, physicians, IT specialists, and many other professional analysts. Deduction, meanwhile, is an interpretive approach used by high school students writing crappy five-paragraph essays, defense lawyers trying to keep their clients out of jail, and intelligence analysts who want to cherry pick details to support the invasion of another country.

Of course I’m being somewhat facetious with this second definition. In reality, most people switch back and forth between deduction and induction when they are trying to solve a problem.

Despite my facetious definition, however, many writing theorists agree that deduction offers a superior approach to presenting information.

Deductive writing means that a writer presents the main idea at the beginning of a paragraph instead of waiting for the end. The writer then supports this deductive statement with evidence.

To illustrate the difference between these approaches, imagine a writer who only knew how to use an inductive approach. When it came time to explain why hand washing is important, such a writer might generate something like this:

The Importance of Hand Washing

People who don’t wash their hands after leaving the bathroom touch other things with their unwashed hands. Then other people touch the same spots, or perhaps even shake hands with the unwashed person. Bad germs that were not washed off can then move from the unwashed hands of the first person to the unwashed hands of the second person. To prevent the spread of germs, it is therefore important for people to wash their hands after using the bathroom.

This approach risks hiding the main idea from a busy reader. Hand washing is a simple concept and so this might not seem like a criminal violation of clear writing, but when topics become complicated and unfamiliar a reader will find themselves skimming over important information looking for “the bottom line.”

Now here’s a deductive approach to the same information; I’ve simply placed the last sentence of the above paragraph at the beginning of this paragraph and deleted the word “therefore”:

The Importance of Hand Washing

To prevent the spread of germs, it is important for people to wash their hands after using the bathroom. People who don’t wash their hands after leaving the bathroom touch other things with their unwashed hands. Then other people touch the same spots, or perhaps even shake hands with the unwashed person. Bad germs that were not washed off can then move from the unwashed hands of the first person to the unwashed hands of the second person.

As you can see, the evidence is the same in both paragraphs—it’s just packaged differently so that the main conclusion comes first. A busy reader can read the first sentence of this paragraph and move on—or read for more detail if they so desire.

In conclusion, induction may be beautiful and appropriate when it comes to fiction and creative nonfiction. But if Sherlock Holmes wanted me to write up a investigatory report explaining the case described in The Hound of the Baskervilles, I’d begin with deduction: “We have determined that Jack Stapleton (R.I.P.) was responsible for the crimes committed at Baskerville Hall based on the following evidence.”

If you’re still on the fence about my assertion that deduction is superior, I invite you to go back to the beginning of this post and read the first sentence.

Sometimes “going on a journey” with a writer and following their logic can be exciting, but in most cases we just don’t have that kind of time. It’s a risk to tell yourself that a reader is going to be so thoroughly entranced by your writing that they are going to wait for the end to find out the point.

Other pearls of professional wisdom:

• Jiro Dreams of Sushi (as a metaphor for professional writing)
• The Four Elements of a Finding