Right now, there is a high probability that nobody will have an outright majority of pledged delegates going into the Republican convention. What happens then? Chaos. Glorious, beautiful, political science-informing chaos.
Or, not quite chaos. We have a "brokered convention." The question, though, is as follows: who brokers a brokered convention? Up through 1968, the brokers were the party leaders, who could pretty much do whatever they wanted. Now, it's different. The Republican convention will have 2472 state and local-level party functionaries, pledged to various degrees on the first ballot to vote a certain way. If that first ballot doesn't give any one candidate a majority, we get more ballots, but it will be the same people voting. So, this won't quite be like an old-fashioned brokered convention, but here's some basic social science.
In a group that large, leaders will emerge. Those leaders could be the candidates, they could be among the 2472 delegates themselves, or they could just be high-profile Republicans. The basic issue is this: when there are more than two choices, voting reflexively for your first choice is stupid. If you rank your preferences as A, then B, then C, you need to ask yourself whether it is more important to try to get A, or to stop C. If it is more important to stop C, then you might have a better chance of doing that by voting for B.
So, if those who rank A first, and those who rank B first are trying to coordinate their votes to block C, what's the most efficient way to do that? The A supporters and the B supporters need at least informal leaders to do the negotiation, and solve the coordination problem.
Here are the choices at a brokered convention:
1) Nominate Trump, who will be the delegate leader, thereby preventing a conflagration.
2) Nominate Cruz because he has more delegates than anyone else not named Trump.
3) Ignore the primaries and caucuses entirely, and nominate whoever looks like a consensus choice.
That's three basic options, but option 3 has plenty of sub-options. That's a lot of choices, and the decision will be made between 2472 people. That can't happen unless some leaders emerge to coordinate. Who will those leaders be? I have no idea. But social science will learn something about leadership emergence by watching.
And of course, I used to think that if Trump didn't get a delegate majority, there would be a Trump/Cruz coalition. That's off the table now that they have attacked each others' wives. So, what do I know?