Our founder, known around the office as simply ‘B’, is a voracious reader of books about all things business and leadership. In this column she each week shares the key points from one of her latest reads.

Your ability to think clearly and rationally is fundamental to your leadership effectiveness, as it enables you to make the best possible decisions based on the available facts, whether it concerns a decision about a capital investment, a key hire, or the future strategic direction of your organization, etc.

I’m therefore always on the look-out for articles, talks and books that help me sharpen my thinking. Being Logical is one of my favorite books on this topic of ‘good thinking’, right alongside “The Little Book of Thinking Big” by Richard Newton and “How to Think Like Leonardo da Vinci” by Michael J. Gelb, which I will come back to in this column some other time.

Being Logical by D.Q. McInerny is a little book (just 129 pages) which provides an easy to read outline of both the prerequisites for and principles of logical reasoning as well as the most common pitfalls and traps that can undermine our ability to reason logically with another party. It may not be the most thrilling read but to me it does for good thinking what Strunk & White’s “The Elements of Style” did for good writing.

Here are my notes:


As a leader you are confronted on a daily basis with the need to make decisions large and small. Your direct reports propose ideas that require your approval while you yourself are also regularly seeking the agreement of your peers and superiors on ideas and issues.

So how can you make sure that you always use logic both when you evaluate the ideas from your team as well as when you seek to reason with your peers and or superiors about ideas and issues? In the first chapter of Being Logical, D.Q. McInerny suggests first of all a number of helpful practices to set yourself up for successful reasoning:

  • Always seek to identify a situation’s uniqueness even when it at first glance looks like a familiar, straightforward issue. The devil is in the detail, which if glossed over can easily lead to a very bad decision. This is why it is a good habit to ask, “What am I missing?” How is this situation different?”, if something seems too obvious, too familiar, too easy.

  • Get the facts straight – i.e. make sure you have the facts that have actual bearing on the outcome under discussion (the RIGHT facts) and that they are not false (the CORRECT facts)

  • Insist on the use of clear language, both by yourself and others – i.e. make all assumptions explicit, don’t mix value statements with facts and don’t obfuscate things by using technical terms or double negatives


D.Q. McInerny spends just a few pages refreshing our knowledge of the four principles of logic:

  1. The principle of identity: If a thing is what it is, then obviously it is not something other than what it is

  2. The principle of the excluded middle: A fact is either true or not true. There is no such thing a half true

  3. The principle of causality: Everything (objects and events) has an explanation for its existence – nothing is the cause of itself.

  4. The principle of contradiction: It is impossible for a matter (object or event) to both be and not be at the same time.

Listed like this, they seem and sound so simple, but, as is so often the case with principles, in real life they are so much more complex and hard to abide by.

For example, D.Q. McInerny aptly warns us, that we at times fail to sufficiently heed the principle of causality:

“We are so pressed by the need to do something that we settle for quick fixes, stop gap measures, while the basic problem remains essentially undisturbed”

So take your time in your search for the rootcauses and don’t jump to conclusions prematurely.

Furthermore, when explaining the process of reasoning, D.Q. McInerny provides two simple but important reminders on how to use language effectively to communicate clearly:

  • Define your terms: We cannot assume that people ascribe the exact same meaning to the same words. It is therefore key to continually seek to clarify statements – our own or those of others – to ensure proper understanding between parties.

  • Be explicit when using general statements: When trying to make their point, people can at times get a little carried away and overstate things by making un-validated universal statements such as “All vendors ….”. Whenever you hear a statement like that, ask people to be explicit. For example, “Which vendors are we talking about? And how many are you referring to?”


As a leader we are often on the receiving end of reasoning by others, seeking our approval or a decision. As you listen and try and follow their logic as they state their case, it would serve you well to keep an eye and ear out for some common patterns of mis-reasoning that people tend to make, whether by mistake or intentional.

In Being Logical, D.Q. McInerny provides a detailed description of 28 of these so-called logical fallacies – i.e. typical patterns of mis-reasoning. Below I have listed 6 logical fallacies, which are particularly common in business contexts. It is important to call them out when you notice them undermining someone’s reasoning.

  • False assumptions: If one begins an argument with a false assumption, one’s conclusion can only be false

    • Do: Ask people to start by stating and validating their assumptions

  • Reductionism: In business people have a frequent need for simplification when dealing with a complicated matter. However, in doing so they may end up focusing on just identifying and addressing a single cause of an outcome and thereby overlook the fact that in reality it may have been caused by a number of causes

    • Do: Be wary of oversimplification. Broaden the conversation by asking what other contributing factors may have played a role.

  • Misclassification: We seek to understand matters by classifying them into groups. However, if we do so without paying due attention to the details of the matter, we may end up misclassifying and thereby misunderstanding the matter at hand.

    • Do: Ask, “Are we looking at this the right way? Is this really a case of …..”

  • The false dilemma: When trying to force a leader to make a decision, people at times may act as if there are just two possibilities of which one is usually significantly less attractive than the other.

    • Do: Make it clear that you are aware that they are artificially narrowing the choices down to create a sense of urgency, but that you want them to provide a full review of the other possibilities.

  • Special pleading: People at times selectively omit significant information because it would weigh against an idea they are proposing. You can spot this easily when something is presented to you in either too positive or too negative a way

    • Do: Ask “Did you come across any information that may cause us to think otherwise?”. In addition, it may be wise to invite an objective third party to review the information for completeness.

  • The democratic fallacy: That a majority of people in a group beliefs something to be true has no bearing on the truth or falsity of the matter in question. Majorities can be wrong.

    • Do: Stick to the facts and logic. Opinions are just that – opinions. You are looking to use facts and logic to establish the truth.