Independence is important to intelligent decision making for two reasons. First, it keeps the mistakes that people make from becoming correlated. Errors in individual judgement won't wreck the group's collective judgement as long as those errors aren't systematically pointing in the same direction. One of the quickest ways to make people's judgements systematically biased is to make them dependent on each other for information. Second, independent individuals are more likely to have a new information rather than the same old data everyone is already familiar with. The smartest groups, then, are made up of people with diverse perspectives who are able to stay independent of each other. Independence doesn't imply rationality or impartiality though. You can be biased and irrational, but as long as you're independent, you won't make the group any dumber.
Bubbles and crashes are textbook examples of collective decision making gone wrong. In a bubble, all of the conditions that make groups intelligent -- independence, diversity, private judgement--disappear.
The smartest groups, then, are made up of people with diverse perspectives who are able to stay independent of each other. Independence doesn't imply rationality or impartiality, though. You can be biased and irrational, but as long as you're independent, you won't make the group any dumber.
It is easy in the world to live after the world's opinion; it is easy in solitude to live after our own; but the great man is he who in the midst of the crowd keeps with perfect sweetness the independence of solitude.
Ralph Waldo Emerson (1803 - 1882)
Source: The Selected Writings of Ralph Waldo Emerson (Modern Library)
In addition to self-awareness, imagination and conscience, it is the fourth human endowment-independent will-that really makes effective self-management possible. It is the ability to make decisions and choices and to act in accordance with them. It is the ability to act rather than to be acted upon, to proactively carry out the program we have developed through the other three endowments. Empowerment comes from learning how to use this great endowment in the decisions we make every day.