In a New York Times story on Pakistan and Afghanistan, David Sanger writes:

Inside the Pakistani Army and the intelligence service, which is known as the ISI, it is an article of faith among some officers that the United States is deceiving them, and that it will replay 1989. If that happens, some Pakistanis argue, India will fill the void in southern Afghanistan, leaving Pakistan surrounded by its longtime enemy. So any talk of exit strategies is bound to reaffirm the belief of some Pakistani officials that they have to maintain their contacts with the Taliban — their hedge against Indian encroachment.

According to Matt Yglesias, this makes no sense because:

[It] seems in tension with the other popular theory that we need to stay in Afghanistan because a Taliban takeover would destabilize Pakistan. Or perhaps it’s better to say that the reasoning is circular. To win in Afghanistan we need to convince the Pakistanis that we’re staying forever, since otherwise they’ll back the Taliban and we won’t be able to beat the Taliban which we need to do as a favor to the Pakistanis. See!

I don't see the circularity. Yglesias is assuming that if we leave, and if the Pakistanis decide to once again back the Taliban, that decision will be in the best interest of Pakistan. In fact, as Pakistan is learning all too well, supporting the Taliban can boomerang, and weaken Pakistani security instead of fortifying the country against India. What makes us so confident that this same cycle will not repeat itself?