Today Scotland votes on independence: a fifty-fifty referendum on leaving the United Kingdom. It's gone from a long shot to a statistical dead heat, and nobody can say for sure how the vote will go. But what's certain is that Scotland's old relationship with the rest of Britain is finished. The Scottish independence movement will not just go away if they come up a couple percent short; they're never going to give up now that they've gotten this close. And if a united United Kingdom squeaks by, Scotland will expect to be given much more autonomy than it's had so far. In fact, this week the leaders of all three major parties have had to promise them that autonomy. So no matter how the vote goes, it's fair to say that David Cameron and his Conservative Party have managed to lose Scotland. They should pay a price for that.

The format of the vote is Cameron's fault. Cameron insisted that the most popular middle-ground option, so-called "max devo" or maximum devolution, which would have kept Scotland inside the United Kingdom but given it more power over its own affairs, be kept OFF the ballot. He made sure that it was an all-or-nothing vote: accept the status quo or leave the nation entirely.

I'm sure Cameron viewed this as masterful strategy: getting what he wanted by allowing no other workable option. You can choose between having it David Cameron's way and having this delicious shit sandwich. But it's backfired. Given a choice between a radical break and Cameron's status quo, many Scots would clearly prefer a radical break. Some of the most persuasive arguments I've heard  for a "Yes" vote on independence have been from people who said that what they really wanted was max devo, and that they were given no choice.

Pro tip to David Cameron: when people would rather eat a shit sandwich than spend time in your company, you're in no position to play the tough guy.

Now, of course, the danger of secession is so high that Cameron has had to troop up to Scotland with the Labour and Liberal party leaders and promise something close to max devo anyway. But many Yes voters hear that as an empty promise. For good reason, too: there are no specifics about what these "new powers for Scotland" would mean, and it's a promise to do something the voters want if the voters agree to give up all their leverage first. A promise like that isn't worth the paper it's not written on.

On the other hand, if No squeaks by, Cameron is in the position of having more or less promised to give Scotland the thing that he didn't want to give them and that he made sure was not on the ballot. So instead of exactly what he wants or an unpalatable alternative, he now faces a choice between exactly what he doesn't want and an unpalatable alternative. It's a kind of strategic masterpiece, carefully orchestrating his own defeat. It's a shit sandwich David Cameron prepared for himself, with his own two hands.

Now, most of the Scottish voters are far to Cameron's left, and he may think his Conservatives will gain politically if a whole region of Labour voters leave the country. But that's almost the definition of short-sightedness, and Conservatives who collude, even indirectly, in the breakup of the United Kingdom have failed at everything their party stands for. No one will admire a Conservative Party that allowed the dissolution of Great Britain. How could they? Churchill famously said that he hadn't become Prime Minister to preside over the dissolution of the British Empire. David Cameron now risks being the Tory MP who presided over the dissolution of Britain itself.

I'll admit that in my heart I'm hoping for a No, and a continued Great Britain. That's not because I'm a great Anglophile. (I'm from Boston, after all, where declaring independence from Britain is considered a heroic tradition.) But history, as I best understand it, suggests that Scotland will be dominated by its larger, wealthier southern neighbor no matter what, simply because that neighbor is larger and wealthier. Union, on balance, probably allows Scotland better terms in that relationship.

Remember how England took over Scotland: the King of Scotland inherited the English throne. After many decades of anxiety that the King of England would somehow get the Scottish throne and take over the country, the reverse happened. The King of Scotland took over England, and that ultimately put Scotland under England's power. For the last four hundred and eleven years, captive England has led conquering Scotland in chains, because the fundamental power difference is about things that no treaty can change. It's political gravity: the smaller country falls into the larger one's orbit. That underlying fact won't change with today's vote. But the strength of England's hold on Scotland will, win or lose.