A group of researchers in British Columbia, Canada, wanted family physicians to adopt a medical intervention that reduced senior citizens’ frailty.^[1] A scientific study concluded that the intervention resulted in a significant delay in the onset of, and in some cases reversed, frailty. The researchers had evidence–they knew their methods worked.

There existed no fee code, however, that doctors could use to bill for the medical intervention. After a quick financial analysis, most physicians concluded they would lose money if they adopted this program. They knew performing the intervention risked making their practice financially unviable.

Through scientific research, doctors knew how to delay frailty. Through economic analysis, they knew they were unable to adopt these research findings.

Knowledge is required but insufficient for wisdom. What, however, is knowledge? How do we come to know something? What happens when different ways of understanding lead to conflict, as the above example demonstrates? Whose knowledge is relevant for a given situation? Can we ever know enough to eliminate uncertainty?

This chapter addresses these questions by presenting an exploration of rationality. It first defines what rationality is and then gives a framework through which to understand it. It will then explore practical reason and discuss the power of blending different forms of rationality to solve hard problems. It then closes with a discussion on why knowledge is required but insufficient for wise action.

Let’s start by establishing what rationality is.