When the Wright brothers said they thought together, what they really meant is that they argued together. One of their pivotal decisions was the design of a propeller for their plane. They squabbled for weeks, often shouting back and forth for hours. “After long arguments we often found ourselves in the ludicrous position of each having been converted to the other’s side,” Orville reflected, “with no more agreement than when the discussion began.” Only after thoroughly decimating each other’s arguments did it dawn on them that they were both wrong. They needed not one but two propellers, which could be spun in opposite directions to create a kind of rotating wing. “I don’t think they really got mad,” their mechanic marveled, “but they sure got awfully hot.”

The skill to get hot without getting mad — to have a good argument that doesn’t become personal — is critical in life. But it’s one that few parents teach to their children. We want to give kids a stable home, so we stop siblings from quarreling and we have our own arguments behind closed doors. Yet if kids never get exposed to disagreement, we’ll end up limiting their creativity.