American Enterprise Institute in Washington, D.C., Greenspan coined one of the most-talked-about phrases of the dot-com era: How do we know when irrational exuberance has unduly escalated asset values,

Irrational numbers such as pi or the square root of 2 have always fascinated humankind. For thousands of years, scholars have investigated the peculiarities of irrational numbers. The larger the

Such reactions may appear irrational under one standard yet reflect a form of rationality adapted to uncertainty, vivid impressions and limited information. What ultimately matters is not labeling people as rational or irrational, but being explicit about which conception of rationality is at work—and why.

Some people make you wonder if you're going crazy when you argue with them, but it's actually their irrationality causing the problem, not your ability to understand. Here are a few signs you're dealing with one of these people.