The Rhetoric of Presentation Design: Logos

I’d like to finish up this series on the rhetoric of presentation design by quoting my favorite, Vulcan, Mr. Spock.

JD Hancock

Logos at its most basic level is about evidence and the presentation of that evidence in a reasonable way. Were we all like Mr. Spock, we would only need logos–facts, evidence, logical organization, clear reasoning, and truth (or Truth). Logic sets Spock and other Vulcans apart from the rest of us humanoids, who are driven by a natural need for authority and our often irrational and destructive emotions. But, if we were all Vulcans, life would likely be pretty boring (Vulcans don’t laugh, dance, drink, or play). As it is, the fact that we are not emotionless, logic-driven alien demi-gods means that we must also ensure our use of logic is engaging, useful, relevant, and understandable.

I love reading blogs (and recently, writing them), and one of my favorites is Six Minutes. Their series on rhetoric and persuasion is practical, useful information for everyday presenters. One of my favorite resources for the practical development of logos is this article from Six Minutes. Andrew Dlugan lays out 17 ways to ensure your logos is understandable (can your audience understand all of your points?), logical (do your points make sense?), and real (is your evidence concrete?). I am going to discuss the ones that most relate to the logos of your slides.

Make your Slides Understandable

1. Use diagrams and charts.

Diagrams: Frugal Dad (Left), GOOD (Top Right), Bureau of Labor Statistics (Bottom Right)

A well-designed diagram, with a bit of help from you, can make for an awesome piece of evidence. This video from infographic masters Column Five sums up why visualizing data helps users make sense of a dense information jungle.

Check out this awesome visualization--it's a response to the current place of Wal-mart in American society and economics.

Check out Alltop’s infographics section for more awesome examples like the ones above.

2. Use progressive disclosure.

Showing only one item at a time draws attention to sequences and processes, bettering your audience's understanding of subject.

 { circle }.. (॓.॔)ノ゙

Showing one element at a time, or progressive disclosure is like your presentation’s “More” button. Using progressive disclosure, as Good does in their series of infographic videos can aid you in revealing information to your audience in an understandable and clear way.

Make Your Slides Logical

1. Leverage commonplaces with a quote.

Speaking to a room full of venture capitalists?


Leveraging the commonplaces or shared values of achievement and single-minded purpose through a quote can help show the inherent logic of your argument.

2. Drive questions with impacting visuals.

My favorite example of using an immediately recognizable image in conjunction with an excellent thought-provoking question is Michael Pollan’s 2009 PopTech talk on the Sun Food Agenda.

Ed Yourdon

Pollan shows us an image of a the now ubiquitous Quarter Pounder with Cheese from McDonald’s and asks the audience if they’ve ever wondered where this meal comes from, what the process is from beginning to end. He then answers the question for the audience by describing the step by step life cycle of a beef cow. He keeps the seemingly harmless image of the burger fresh in the audience’s mind as he exposes them to the reality behind this product. If you haven’t seen Pollan’s talk, it’s a must watch and a fantastic example of how slides can be used to successfully develop each of your rhetorical appeals.

Michael Pollan: Sustainable Food

Make Your Slides Real

1. Apply the picture superiority effect consistently.

Ed Yourdon

Something else Pollan does in his Pop Tech talk that engages his audience and illustrates the validity of his words is his consistent use of the picture superiority effect. Each of Pollan’s visuals features either impacting images (such as his shots of a cattle farm he dubs “Cowschwitz”) or incredibly simple and immediately recognizable pictorals, such as his comparison of how much waste 150,000 cows produce (the equivalent of the entire city of Chicago).

2. Use visuals to reinforce verbal stories.

I’d like to direct you to TOMS as an example of using visuals to reinforce stories.


The story of TOMS shoes is an impacting one; the organization is committed to its “one for one” campaign, whose effort has always been to improve the quality of life of children by providing them with a free pair of shoes.

TOMS doesn't just show you cool shoes; they show you why these shoes matter.


But, it’s not the shoe alone TOMS customers are drawn to–what draws TOMS’ customers is Blake’s story.

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4 thoughts on “The Rhetoric of Presentation Design: Logos

  1. […] Chiara Ojeda of Tweak Your Slides just wrote an amazing blog series on The Rhetoric of Presentation Design.  Click here for the Introduction and Ethos of Presentation Design; the Pathos of Presentation Design; and the Logos of Presentation Design. […]

  2. Alex Uribe says:

    I just bought two pairs of polarized sunglasses and one pair of shoes from TOMS. All thanks to Chiara Ojeda for introducing me to them and the cause. Everyone, especially you Full Sailors should look into TOMS website.

  3. […] understand how rhetoric and the means of persuasion (ethos or credibility, pathos or emotion, and logos or logic) work. An argument is like the Starship Enterprise, flagship of the United Federation of Planets. […]

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