Tag Archives: inductive reasoning

Inductive Reasoning Also Finds Its Way Into Persuasive Speaking

In a previous blog post, I wrote about reasoning as a prerequisite to organizing and wording arguments in a persuasive speech.  We teach the important principles of parallelism and alliteration in our Speech Class Refresher program.  You can read that post by clicking here.

In that post, I focused upon deductive reasoning, of which there are two types:  syllogistic and enthymematic. 

I did not mean for anyone to interpret that post to think that I do not also believe in inductive reasoning in a persuasive speech.

There are four types of inductive reasoning:

by example – give an incident that illustrates the argument; note that an extended example is a case or story – “President Ford introduced WIN – whip inflation now – as a major initiative to turn around economic conditions.”

by cause – show that there is a factor that is a force that produces some effect; always start with the effect – if it is good, put more resources behind the causal factor; if it is bad, minimize or eliminate the factor – “Illegal immigrants have helped businesses maintain steady employment wages.”

by analogy – show that what is true in one case is also true in another; the underlying assumption is that the two items being compared are highly similar – “Truman ended the conflict with Japan by dropping two nuclear bombs.  If Trump does the same with North Korea, we will end any conflict we have with them.”

by sign – make an observation that infers some effect or outcome – since it depends upon an inference, it is the weakest type of inductive reasoning – “The current construction that we now see of new homes and apartment complexes in our city indicate that our local economy is getting stronger.”

Reasoning Underlies Organizing and Wording for Persuasive Speeches

As I taught our Speech Class Refresher course last week, I was helping some of our participants with the main points or arguments they wanted to make for their sample persuasive presentation.

The principle that we taught them was parallelism.  That is, that the points or arguments should begin with the same part of speech, such as an action verb.  A bonus to that is alliteration, which means that the points begin with the same sound.  The example I gave was:

  • With a smart phone, you can text.
  • With a smart phone, you can talk.
  • With a smart phone, you can travel.

It hit me this week that organizing and wording points or arguments is the visible cousin to the invisible reasoning that goes behind them.  A speaker must reason his or her arguments before organizing and wording them.  There are two types of reasoning:  inductive and deductive.

Deductive reasoning typically takes two forms.  One Is syllogistic:

  • Republicans control the House of Representatives, which votes on proposed legislation.
  • The President of the United States, who submits legislation for consideration, is a Republican.
  • Therefore, the President should be able to pass legislation he proposes in the House since the majority of voters are from his own party.

The other type is enthymematic.  An enthymeme is deductive, but omits one of the major premises.  It is either an truncated syllogism, or one that simply allows the listener to reach a conclusion through implied, rather than stated reasoning.

AristotleIn his work, Rhetoric, published in 350 B.C.E., Aristotle said, “the enthymeme must consist of few propositions, fewer often than those which make up the normal syllogism. For if any of these propositions is a familiar fact, there is no need even to mention it; the hearer adds it himself.”  He believed that they enthymeme was the strongest form of proof available to a speaker.

So, converting the example above from a syllogism to an enthymeme, we would say:


  • The President of the United States should be able to pass legislation he proposes because the House that votes on it is Republican.

Notice that we omit the premise that the President is a Republican.  It is only implied.

Important as it is, we rarely teach enthymematic reasoning.  I do not cover it at all in public speaking courses.  I have not seen it in a speaking textbook for many years.

Frankly, since reasoning is not visible to audiences, we have simply stopped talking much about it.  Yet, it is one thing to word and arrange arguments.  It is completely another to properly reason a case with them.  Reasoning is first – wording and arranging is second.