In many (most?) organizations, “being a team player” is code for “being nice” — which, in turn, is often code for “not contradicting anyone.” The problem with this is that it leads to groupthink and mediocre (or often just plain wrong) results.

I think that this Slashdotter has it right: (emphasis added by me)

I’ve worked for years in highly effective teams, and with success. I can tell you what made all the difference: The presence of equals to debate issues with, so that we could talk each other through the problems and emerge from the session with the feeling that we had defined better solutions. Perhaps we are all arrogant nuisances, but as long as we understand and respect each other we keep each other in check, and can function as effective team members.

The “respect among equals” also translates to “respect among people above and below you in the hierarchy” when such hierarchies exist:

• Listen to & consider what your boss says, but call him out on it when he’s wrong or hasn’t justified his assertions.
• Listen to & consider the objections of those below your skill and/or station, but correct them when they’re mistaken and clarify the reasoning behind your positions.

You should only be stating agreement when you reach the same conclusions based on the available information. If you don’t think you have enough information to defend a contrary position, it’s better to state that outright rather than agree by default. The lack of agreement, even without the presence of opposition, might be enough to show that the position is potentially unreliable.

Being a helpful member of a team means working to achieve the same goal as the other team members. It does not necessarily mean following the same process.

Update: Fixed the link to Slashdot. Sorry for that.