William Osler, a cofounder of Johns Hopkins Hospital, once opined that, "Medicine is a science of uncertainty and an art of probability." Medical doctors, like other experts, will experience periods of hesitation and doubt. They know their eff orts will not always produce a positive outcome. Yet, despite the risks and uncertainties of their craft, they know that sick patients need confident physicians.

Patients who have faith in their doctors are more likely to listen to them and abide by their council. Patients who do not trust their doctors, on the other hand, are less likely to take prescribed medications or follow advice about behavioral changes. This is a big problem in medicine—studies show that especially with long-term treatments, patients comply with medical directions less than 50 percent of the time.

Medical treatment adherence is a multifaceted problem, with patient confidence being just one important factor.11 Patients need to have confidence in their physicians, yet many doctors project uncertainty, which sabotages the confidence that their patients need. Without even thinking about it, doctors might use phrases like, "my guess is," "I'm not sure," "let’s see what happens," or "I haven’t seen that before." Doctors and all other experts should project confidence and certainty, rather than hesitation or doubt.

I am occasionally told that statements of uncertainty from doctors are simple honesty, and that honesty is far better than false confidence. This may be true, and it goes without saying that all experts should be honest and forthcoming. But it is possible to be honest and confident at the same time. Yet, many experts place too much emphasis on uncertainty and risk.

Medical literature shows that doctors often underestimate the damage they inflict on their patients by making doubtful or uncertain statements. It is no more honest for an expert to scare a patient about an obscure risk than it is to ignore the risk altogether. The role of the expert is to understand all aspects of a preferred treatment and then propose that treatment with confidence and conviction.