What Is The Illusion Of Certainty And How Does It Affect Decision-Making? [Part I]


Although some people only want to hear that a test or drug is going to be helpful, others are asking for more complete information so that they can make better decisions and minimize risks.


A ‘risk’ is a potential harm and can be described as an uncertainty which can be further described numerically and which allows one to make decisions more easily.

When making decisions, an important observation is that if a treatment is being debated, it suggests uncertainty—in other words, doctors aren’t certain what is best for everyone and all treatments need to be individualized.  Two examples of this—Hormone Replacement Therapy, and Vitamin D supplements—were discussed in Newsweek 1/24/11.

The illusion of certainty refers to the belief than an event is absolutely certain although it may not be.  Three examples of this are:  treatments have only benefits but no risk of harm; there’s only one best treatment; a diagnostic test is absolutely certain.

However, as Benjamin Franklin said, “In this life, nothing is certain but death & taxes”.  And in reality, all world events are uncertain and every attempt to do good may generate unwelcome side-effects!

Therefore, before making any healthcare decision, both doctors and the public have a right to understandable information.  Doctors want what is truly best for their patients but if statistics are presented in a confusing or misleading way, then decisions could be made which would not really help patients achieve their goals and may even cause them more problems.

What kinds of information should be ignored and which are most helpful?  Next time.