Which is more crucial to the success of a startup: the idea or the execution?

Is it the idea or the execution that makes for successful startup? This is one of those debates that seems to have raged on through the ages, for as long as time can remember. Many people here, at Kellogg, believe that it comes down to execution. I had counted myself among them, but I've now started to wonder if this is really the case.

The argument for why execution is important is easy to make. There were social networks before there was Facebook. There were search engines before Google. There were MP3 players before there was the iPod. It was the particular way in which these ideas were executed by their respective companies that allowed them to gain considerable more traction than what had gone previously.

The problem with this argument is that they were already based on fundamentally big ideas with huge opportunity. If these same companies had 'executed' on smaller, worse ideas - would they still have been as successful? If Mark Zuckerberg, Brin & Page or Jobs had decided to use their considerable talents to build a website selling ice online, would he have been as successful? Or would the idea have led to their downfall?

The argument that execution is more important than the idea is attractive. It allows us to believe that we can be masters of our own destiny - that using our own natural talents and capabilities we can make something out of nothing where others might not be able to. The fallacy with this line of thinking, though, is that there are a lot of smart people out there. They are just as capable as you or I. As just one data point, you only have to consider that business schools graduate thousands of them every year.

If there are plentiful capable people out there, what differentiates all these people? Perhaps, just perhaps, it is the idea - the problem - they focus their energies on. If all these people are able to 'execute', as I postulate that they are able to, perhaps it is those who focus on the biggest ideas with the most opportunity that will truly be able to 'make' it.