When God comes to a fork in the road

One issue that sometimes crops up in debates over Calvinism is whether God has libertarian freedom. Could God have chosen otherwise, or are his choices determined? 

That debate isn't confined to Calvinism. It goes to larger issues like the principle of sufficient reason. Likewise, whether God can or should be able to change his mind. 

There's disagreement within freewill theism on how to define freedom. There are two basic models: leeway freedom and ultimate sourcehood. 

Leeway freedom is the ability to choose between alternate possibilities, given the same past–up to the moment of choice. In a sense, I'd say mainstream Calvinism affirms God's leeway freedom insofar as God was free to make the world, not make the world, or make a different world. God had many live options at his disposal. 

However, it's misleading to say God has libertarian freedom in that sense, for unlike human agents, God doesn't have to choose between two (or more) alternatives. In principle, he can act on both alternatives. In principle, he can create a multiverse which exemplifies multiple timelines. Perhaps he has. In that respect, God has greater freedom than libertarian freedom. 

If God's choices were determined, they'd be determined by his own reasons, and not by something outside himself. However, there's a hidden assumption behind that way of framing the issue–as if God is confronted with a binary choice: either doing A or doing non-A. But God doesn't face that limitation. It's within his power to opt for both alternatives. In principle, he can create more than one possible world. When God comes to a fork in the road, he can simultaneously go right and left (figuratively speaking).