Alexander Graham Bell was 29 when he received his patent for the telephone. Guglielmo Marconi was a teenager when be began tinkering with wireless technology. Those Google guys? In their twenties when they launched the Search Engine That Changed Everything. So why do we middle- (or almost middle-) aged managers take such a dim view of Gen Y?On this website there is a debate raging over a story by our 21-year-old editorial assistant. She and her peers, she says, know what they want from work and life, are motivated to get it and don't care much what the "old folk" think. In the comments on this story, the knee-jerk reaction is to dismiss Gen Y as a bunch of brats who will get their comeuppance. But that's wrong. If you really think about it, Gen Y is downright entrepreneurial. They presume that old processes and legacy systems can change. And they expect to be taken seriously. In many companies today, new ideas have to fight an uphill battle against the status quo. Harness their energy and their attitude constructively, and the Gen Y workforce can be the fuel that drives innovation.Every 21-year-old thinks he knows everything. Gen Y has much to learn about, well, everything. But that doesn't mean they know nothing. I am 42. I have been employed almost continuously since I was 15. I remember, in sometimes excruciating detail, the mistakes that I made on the way to where I am. But what shaped my career were the managers and mentors who were willing to give me the benefit of the doubt. Who did not dismiss my ideas just because I was young. Who didn't stamp on my ambition or my attitude, but helped me to channel it. If we're smart, we'll stop deriding Gen Y and teach them the ropes. And if we're willing to listen, we can learn from them, too.