Also referred to as top-down thinking, deductive reasoning is one type of valid reasoning; the other main type is inductive reasoning. Through deductive reasoning, one draws a specific conclusion from general logic and true premises. More simply put, if A=B, and B=C, then A=C.
Both inductive and deductive reasoning have their place in a wide range of professions and industries. They can help businesses and individuals make informed, critically sound, and reasonable decisions, as well as develop and implement new ideas.
How does deductive reasoning apply to the career world? Here is how to use it to excel in your job and advance your organization.
What's the difference between inductive and deductive reasoning?
People often confuse inductive and deductive reasoning, although the two methods of reasoning are, in fact, opposites.
As discussed above, deductive reasoning draws a conclusion based on valid premises. If the premises are, in fact, true, then the conclusion will be true as well.
In contrast, inductive reasoning, also called bottom-up reasoning, derives conclusions from premises that are believed to be but are not necessarily true. Through this type of thinking, people draw conclusions from general knowledge and observations.
Because inductive reasoning relies on unconfirmed premises, it is more likely to be false than deductive reasoning. That is not to say it is always false. Sometimes, inductive reasoning, like deductive reasoning, is used in the scientific process to form hypotheses and theories, some of which, when tested, are confirmed to be valid.
Examples of inductive reasoning
1. I leave for work at 8:00 am every day. I have never been late to work. Therefore, if I continue to leave for work at 8:00 am, I will never be late.
2. All of the women in my office wear slacks. Therefore, all women wear slacks.
3. Everyone I know with a high-paying job went to college. Only people who went to college attain high-paying jobs.
4. My boss said someone is getting a promotion. Mary has done the best work this year. So, Mary must be getting the promotion.
Deductive reasoning examples
The classic example of deductive reasoning comes from Aristotle, who wrote:
All men are mortal.
Socrates is a man.
Therefore, Socrates is mortal.
Deductive reasoning can also apply to your career and organization.
People who are good at deductive reasoning can develop ideas that may be very valuable to their businesses and apply sound logic to decisions they make. Examples include:
1. When analyzing marketing analytics from a campaign, a marketing manager finds that most consumers are clicking the links between 5:30 and 8:00 pm. So, she decides to deploy her next campaign at 5:30 pm.
2. Emma’s boss informs her team that the employee who makes the most sales this year will receive a bonus. Emma worked hard and made the most sales this year, so she is looking forward to receiving her bonus.
3. Market research a makeup brand has conducted shows that women in their 20s and 30s are willing to pay more for an eyeliner that does not run. So, the brand highlights that their eyeliner stays put and is long-lasting in its advertising efforts.
4. Families with children are the target demographic for a brand of frozen dinners. Focus group members have said that they are looking for meals that are healthy and that their children are picky eaters. Therefore, the brand is working to demonstrate the nutritional value and emphasize that the dinners appeal to people of all ages.
Deductive reasoning in the hiring process
While deductive reasoning may be a bit specific to include on your resume unless the job description identifies it as necessary (or you know that it is especially valuable in your position and industry), it is a good skill to highlight in your cover letter and the interview process.
You might, for instance, describe how you used your logic and reasoning skills to develop an idea that panned out and improved the business. You might also explain how you solved a problem for yourself or the organization by using deductive reasoning.
Can deductive reasoning be false?
Deductive reasoning can lead to a false conclusion if one of the originating premises is false or invalid.
All sales are made between Black Friday and Christmas.
A sale was made today.
Therefore, today must fall between Black Friday and Christmas
In the above example, the conclusion would be valid if the two premises were correct. However, the original statement that “All sales are made between Black Friday and Christmas” is not true; therefore, the conclusion is also invalid. If the premises on which the conclusion is based are true, then the conclusion must also be valid.
Inductive reasoning, on the other hand, can and often is invalid, even if both original premises are true.
Many sales are made between Black Friday and Christmas.
A sale was made today.
Therefore, today must fall between Black Friday and Christmas.
In this case, both of the original premises are true, but the conclusion is not necessarily valid; just because many sales are made between Black Friday and Christmas does not mean that all sales are made during this period, so it doesn’t logically follow that today is necessarily a date in that window.
Is there any value in invalid deductive reasoning?
Even though incorrect deductions, people can make advances in science, business, and other industries. When people test hypotheses based on premises they believe to be true and find the result invalid or incorrect, they then realize that one or more of the original premises must be untrue. For example, believing the Earth is flat would lead one to deduce that she would ultimately reach the edge, and if and when the second premise never occurs, she must revise her original supposition.
Inductive reasoning, too, is important for drawing conclusions. Many hypotheses are based on premises that are unproven, and testing conclusions drawn from these premises can lead to new discoveries.