5 Types of Evidence Used to Persuade Your Audience
April 5, 2022 by Bill Rosenthal

5 Types of Evidence Used to Persuade Your Audience

If you’re a regular reader of this blog, you have seen me write many times that persuasion is an emotional process. The way to persuade an audience is to find their pain and offer them relief for it. If they don’t feel the pain, it’s up to you to make them feel it. In a sales presentation, for example, if your product can save a customer a million dollars per year, then you have the opportunity to relieve the audience of a million-dollar cost. Pain relief like that is nothing if not emotional.

But that doesn’t mean there’s no place for evidence in your presentation. If you have the audience feeling pain and have given them a glimpse of a way to relieve that pain, you are most of the way to persuading them. And that is the time to introduce evidence. The decision-making process may be fundamentally emotional, but the audience most likely believes they make all their decisions based on facts and reason. There’s no need to muddy the waters by trying to argue with them about this self-image. In addition, evidence will help you clear away any remaining skepticism and also provide members of the audience with material they can use to persuade their bosses. 

Evidence for persuasion comes in five forms. 

  1. Data. Data is the type of evidence used most often in presentations. Data are the statistics and facts that have put so many of us to sleep in the course of someone else's presentation. You need to remember that data is one type of evidence among many, and it’s not the most effective type. When you’re preparing the presentation, pull all the facts and statistics together, then choose a few of your most powerful to present. Keep the rest for the question-and-answer period. 
  1. Expertise. This is the opinion of someone your audience will accept as an authority on the subject – an expert, in other words. Expert opinion is valuable if you have it. That’s one of the reasons they often bring in expert witnesses during the trial phase of Law & Order
  1. Cases. This type of evidence is most useful when you have examples that are close to the experience of your audience members or particularly meaningful to them. Cases or examples are particularly apt with business audiences because they show real world applications that are easy to understand. Sometimes they even provide a hint of competitive pressure. 
  1. Image. This is a way of relating a new thing (your recommendation) to something familiar. Image is an explanatory form of evidence; it doesn’t prove anything. To say that your new centralized production plan operates like the solar system, with Department X in the center, is just a way to help the audience visualize it. Analogies work very well when acceptance of the recommendation requires some learning.
  1. Story. This is something from your personal experience. It may not readily prove your contentions, but it brings them to life. Handled well – which is to say, with authenticity – it can be the most powerful form of evidence.

Even though evidence plays only a supporting role in the persuasive process, it will probably be the largest single section of your presentation. Be expansive with it. But don’t make the mistake of many presenters, who try to overwhelm the audience with evidence and wear down their resistance. You may indeed be able to wear them down, but bored people are not persuaded. They’re just bored.