Skip to Content

This is the third blog, in a series, on applying critical thinking to information to make well-informed and sound decisions. The blogs, and white paper, are the result of a collaboration between SAP and published authors, and professors of Critical Thinking, Dr. Sharon Bailin and Dr. Mark Battersby. Subscribe to www.sap.com/BINews to read the subsequent blogs on this topic.

Nothing is worse than misconstruing the information provided by an excellently administered business intelligence system. Unfortunately, it is more common than you think, and many people don’t even realize they are making errors that counteract the benefits of BI.

Avoiding The Most Common Reasoning Errors

One of the key concepts associated with critical thinking is the concept of fallacies. Fallacies are usually defined as common reasoning errors — common arguments that are extremely persuasive but actually provide little or no support for their claims. There are, in fact, a great many such fallacies, but in this blog we focus on a few of the most common ones, and those which are perhaps most destructive of good decision making.

Ad Hominem

One of the most common fallacies is the ad hominem. This fallacy consists of rejecting someone’s argument simply on the basis of who the author is or what their motivation is. To dismiss someone’s argument on the basis of their hypocrisy or inconsistency, despite their putting forward cogent, credible and well sourced arguments, is to engage in the ad hominem fallacy.


In everyday discussions, there is seldom a better way to get a discussion off-topic and make it unproductive than to attack someone in the discussion on the basis of their personality, motivation, gender, or other personal aspects. To the extent that the participants are putting forth arguments using credible evidence, their motivation or facts about their person are strictly speaking irrelevant to assessing whether their arguments are indeed credible. Should you find yourself an object of such an attack, do not try to defend yourself, your background, or your motivation. Rather, the best response is “Excuse me, we are having an argument about X, not about me. Let’s return to the subject at issue”.

Anecdotal Evidence

Another common fallacy that shows up in everyday discussions is the appeal to anecdotal evidence. This fallacy involves citing a story or personal example as if it proved a generalization. There is, of course, nothing wrong with citing relevant experience and stories in support of your position. The problem with people giving stories is that a story is only one case, and one case hardly supports a broad generalization.

In the age of big data, it is easy to see that individual experiences may well not be representative of the more general case. Our life, our experiences, or our acquaintances provide a very limited and biased selection of data. We may be discouraged from visiting a certain city after hearing our friend’s dramatic story about being mugged there. But one story, no matter how vivid, is hardly an adequate basis for concluding that that city is excessively dangerous. The issue is not that personal experience is  irrelevant but rather that most people give their own experience or stories they have heard too much weight for their evidential worth. Faced with an appeal to anecdotal evidence in a discussion, the best response is simply to say, “I understand that that is your experience but, with all due respect, that is just one case and I think we should look at a broader range of evidence and the experiences of others”.

False Dilemma

Another common fallacy is known as the false dilemma.  This is something we often do it to ourselves.  “Either we go to the movie downtown or we stay home.” “Either we go to Hawaii or to Mexico.”  “Either we invest in the new and innovative product or we will be left behind in the competitive race.“  Very little in life is ‘either-or’ and yet we are often tempted by such a simple dichotomy. The key to avoiding a false dilemma when making a decision is to force yourself or your group to consider a broad range of alternatives before narrowing  the decision space.  And if you feel skewered on the horns of a dilemma, the solution is not necessarily to accept the least undesirable alternatives. It may be, rather, to return again creatively to see if other genuinely desirable alternatives can be found. Hawaii or Mexico?  What about a cruise?  What about the local movie theatre or a live music bar…?


Straw Person

How often have you found yourself saying in a discussion “No, That is not what I mean” ? In doing so you were claiming that your discussant was guilty of the straw person fallacy.  This fallacy consists of an attempt to refute someone’s claim or argument by attacking a different, usually over simplified claim that they don’t hold.  The misleading characterization of an opponent’s view is almost always so loaded that the person making that misstatement doesn’t even have to argue against it. It is surprisingly easy to misunderstand someone, especially someone you disagree with.  The best procedure to avoid indulging in the straw person fallacy yourself is to ask your opponent:  “Is this what you are saying?”  You will be surprised how often they will say “No, what I was saying was …”


Confirmation Bias

One very common human tendency is to ignore objections to one’s view and to seek only affirming evidence.  Known as confirmation bias, this natural human tendency may also be exacerbated by group think as groups often work together to support the common view and no one questions (or dares question) the prevailing view.  The antidote to this tendency is to force yourself or your group to consider counter evidence and counter arguments. Our experience in teaching is that students will often say “but there are no good arguments for the view I oppose.”  On controversial questions this is, of course, not true, But getting your mind or group to give consideration to counter evidence or opposing views is unquestionably a challenge.

Identifying fallacies in the actual flow of discussion takes a bit of practice, but being able to do so can save you and your group a lot of needless disputes and can promote a respectful and thoughtful decision making process.

To report this post you need to login first.

1 Comment

You must be Logged on to comment or reply to a post.

Leave a Reply