“If men define situations as real, they are real in their consequences.” Thomas noticed when people are trying to predict future events, they make a lot of assumptions about the present. If those assumptions are powerful enough, the resulting actions will lead to the predicted future. The easiest example of this is the rumor of a shortage. If you believe there will be a shortage of toothpaste, you will go and try to buy some before the stores run out—just like everyone else. Sure enough, the shortage occurs.
