Many people distinguish between two basic kinds of debate: inductive and deductive. Induction is usually described as moving from the specific to the general, while deduction begins with the general and ends with the specific; debate based on experience or observation are best expressed inductively, while debates based on laws, rules, or other widely accepted principles are best expressed deductively. Consider the following example: John: I've noticed previously that every time I throw a ball up, it comes back down, so I guess this next time when I throw it up, it will come back down, too. Mary: That's Newton's Law. Everything that goes up must come down. And so, if you throw the ball up, it must come down.
 
 John is using inductive reasoning, debating from observation, while Mary is using deductive reasoning, debating from the law of gravity. John's debate is clearly from the general (the law of gravity) to the specific (this throw); John's discussion may be less obviously from the specific (each individual instance in which he has observed balls being thrown up and coming back down) to the general (the prediction that a similar event will result in a similar outcome in the future) because he has stated it in terms only of the next similar event, the next time he throws the ball.

 
As you can see, the difference between inductive and deductive reasoning is mostly in the way the discussions are expressed. Any inductive discussion can also be expressed deductively, and any deductive discussion can also be expressed inductively.
 
 Even so, it is important to recognize whether the form of a discussion is inductive or deductive, because each requires different sorts of support. John's inductive discussion, above, is supported by his previous observations, while Mary's deductive discussion is supported by his reference to the law of gravity. Thus, John could provide additional support by detailing those observations, without any recourse to books or theories of physics, while Mary could provide additional support by discussing Newton's law, even if Mary herself had never seen a ball thrown.
 
 The appropriate selection of an inductive or deductive format is vital for a specific first steps toward sound discussions.

 

Inductive Reasoning or Thinking

Inductive reasoning works the other way, moving from specific observations to broader generalizations and theories. Informally, we sometimes call this a "bottom up" approach . In inductive reasoning, we begin with specific observations and measures, begin to detect patterns and regularities, formulate some tentative hypotheses that we can explore, and finally end up developing some general conclusions or theories. (See the graphic on the right of the page, It demonstrates how Inductive Thinking is a bottom to the top approach.)

How do I apply this in the "Real World"?

Scenario: Your supervisor has asked you to install an application on the web server. This application measures many of your server's real-time  performances, such as; disk, network, and memory performance.

You respond by stating, "I have made an observation (Observation) regarding this application, every time (Pattern) we install it on one of our web servers, it greatly decreases the server's overall performance". (Tentative Hypothesis) I don't believe it is meant to be installed on the server we are monitoring. (Theory)

Your Argument: I don't believe we should install this directly on the web server.

Why is this important?

You have communicated sound reasoning to your supervisor as to why we should not install this application on the webserver. Compare this to the following response. "I think that application is junk, it slows everything down."

If you were the supervisor, which statement would you value more?
 
  Another Approach

Deductive Reasoning or Thinking

Deductive reasoning works from the more general to the more specific. Sometimes this is informally called a "top-down" approach. We might begin with thinking up a theory about our topic of interest. We then narrow that down into more specific hypotheses that we can test. We narrow down even further when we collect observations to address the hypotheses. This ultimately leads us to be able to test the hypotheses with specific data; a confirmation (or not) of our original theories.

How do I apply this in the "Real World"?

Scenario: Your supervisor has asked you to install an application on the web server. This application measures many of your server's real-time  performances, such as; disk, network, and memory performance.

You respond by stating, "The accepted practice with other types of performance monitoring applications recommend using remote monitoring, by installing the application on another server." (Theory) "I believe if we install this application of our web server, we will see the same performance degradation." (Hypothesis) "I installed this application on the backup webserver and I noticed the database accessed much slower." (Observation) "I installed the application on another server and observed the backup webserver degrade in performance when I initialized the application on the backup web server. (Conformation)

Your Argument: I don't believe we should install this directly on the web server. We can expect the same decrease in performance if we install it directly on our web server.

Why is this important?

You have communicated sound reasoning to your supervisor as to why we should not install this application on the webserver. Compare this to the following response. "I think that application is junk, it slows everything down."

Again; "If you were the supervisor, which statement would you value more?"

Wisdom doesn't automatically come with old age. Nothing does - except wrinkles. It's true, some wines improve with age. But only if the grapes were good in the first place. Abigail Van Buren
 
"This site is authored and maintained by Randy Larson. It is not an official website of the Maricopa County Community College District, and Maricopa is not responsible for the contents of this site."