I was a skeptic of the deal that President Obama struck with Iran. Not only did I think that it was based on false premises but I thought that the U. S. realized precious little from the deal that it would not have obtained otherwise and that the main objective of the deal was to burnish President Obama’s list of foreign policy accomplishments, not a legitimate reason.
However, once it went into force with all of its costs to the U. S. front-loaded, those became sunk costs. Now abrogating the deal would be foolish. If the deal has any benefits for the U. S. and if those benefits can be realized, the only way they can be realized is to leave it in force.
The reason I bring this up is not simply because President Trump is considering decertifying Iran’s compliance with the treaty but because it reflects a more general problem with American politics and policies over the last decade or so. Just because the previous administration made mistakes doesn’t mean that doing the opposite isn’t just as stupid. There are such things as path dependency and time dependency. You can’t unbreak eggs and there are such things as sunk costs.