Recent tweets by Nancy Duarte about her reading up on classic rhetoric and a clean-out of my book shelf with old McKinsey training material triggered this post. How can we use the ancient rules of logic and rhetoric in our presentations? Some of my observations.
Logic is necessary but not enough to convince. The perfect logical argument often fails to make people believe your message with their heart. There are still many people that smoke despite this:
  1. Smoking causes cancer
  2. Cancer kills
  3. People do not like to die
  4. Therefore: stop smoking.
The Greek philosopher Aristotle was well aware of this. Logic and rhetoric are often confused to be the same thing. Actually, logic (logos) is one of three components of rhetoric. The other two 2 are ethos (credibility of the speaker) and pathos (emotional appeal to the audience).
Why is logic so popular among McKinsey consultants? A number of reasons:
  • Lack of time. There is an often overlooked difference between a problem solving structure and a solution presentation structure. Logic is a great tool to solve a problem: cut your issue up in pieces, find facts and other evidence to solve sub-problems, and finally build up the overall solution again from the component solutions. Management consultants often stop there and do not invest time to translate the problem solving structure into a compelling and convincing story to communicate the solution. It is not that they don't want to, at 2AM before the final review meeting there is often simply no time left.
  • Like-minded people. Management consultants usually are very logic-driven people. It is logical work, that attracts logical people, who hire more logical minds. So, the language between management consultants among themselves is highly logical. Some people however have a totally different brain structure (clients of management consultants included).
  • Collaboration. A logical language and structuring technique is very well suited for people that need to work together but have never met each other before. Once you have learned the methodology, you can put a team of consultants from different countries together that can produce results almost immediately.
There a number of logical concepts that any presenter should use, regardless of the audience, regardless of the structure you want to use for your story.
  • MECE, consultant speak for no gaps and no overlaps. Say things once/do not repeat yourself/keep things short. Group points that are related together, together.
  • The number 3. Most people can easily remember 3 points, I like breaking up a story in 3 key messages for people to remember.
  • Levels of logic. Separate the key points of your story and the sub points that support the key points. Build a tree-like structure for your argument.
And an important one: in what order to present your story? Most stories can be crafted using 3 components: the situation, the complication, and the resolution. The order in which you chose to present them sets the tone of your story:
  • Solution - situation - complication, this is what consultants use most of the time, a no-nonsense approach. If you do not have time to read the whole story, you get the answer in the first paragraph/on the first slide. Functional, but boring.
  • Situation - complication - resolution, the most natural one to present a case, starting relaxed, adding stress but then calm things down again at the end.
  • Complication - situation - resolution, a flow of arguments that creates a sense of urgency.
Now, where do we need that classical rhetorical argument? There are two types of logical arguments, and I am making the Case (with a capital C) that you do not need the second one very often:
  • Inductive: you take a number of specific examples and draw a generic conclusion from it. This is the form of logic I use most in my presentations. A simple summary of tangible (i.e., not abstract) examples is a good way to get ideas across.
  • Deductive: you present a series of true statements, the combination of which produce a very specific conclusion. This is the pure logic used by mathematicians. (All men are mortal, Socrates is a man, therefore Socrates is mortal). This one is harder to use in presentations. It is abstract and requires a logical audience. The only times I had to use it in my 17 years as a strategy consultant was in cases with a highly controversial and counter-intuitive recommendation. This is not a situation of a presentation in front of big audience, but rather a one-on-one meeting with an executive, taking him step by step through your analysis: "Do you agree with this?" "Yes." "Do you agree with that?" "Yes." "Then you must agree with this!" "Huh, wait a minute, again."
To make a long story short. Use logic to develop the solution, but then take a step back and think how you can communicate that solution best. Communication and problem solving is not the same thing.
If you are interested in McKinsey-style story line development you could read The Minto Pyramid Principle: Logic in Writing, Thinking, & Problem Solving
P.S. Speaking about deductive logic, the name of my company is Axiom One. An Axiom is a basic assertion that you assume to be true (it is so basic that you cannot prove it), this basic fact can then be used to construct more complex logical arguments)
Disclosure: if you purchase a product on Amazon through links on this site, I earn a small commission.