President Obama’s supporters like to argue that his Republican challenger, Mitt Romney, either has no substantive policy differences with the president or that his policy prescriptions have “neo-conservative” written all over them—or more recently, that Romney has taken both positions, depending on the audience and the venue.

In truth, if one takes the time to look more closely, the former governor does have differences with the president on matters such as Syria, Iran, China and the military’s budget.  Nor is it the case that his team of national security advisers is led by a cabal of neo-cons. As with every GOP presidential campaign in recent memory, Romney’s team contains a mix of views from around the Republican Party.

No doubt the nation deserves an idea of where a candidate stands on the issues—especially in the area of foreign and defense affairs where a president’s constitutional responsibilities are the clearest.  But it would be misleading for anyone to suggest that those views are a predictor of exactly how a president will behave once in office.  The fact is the world gets a vote in how president’s carry out their duties, a point typically ignored in the run-up to Election Day but which has been borne out time and time again by recent history.

It may be hard for folks to do but it’s useful to remember that George W. Bush came to office in January 2001 promising a more humble foreign policy, skepticism about nation building, and a view that the country had entered a period of “strategic pause” in which we would face no serious strategic competition for another decade at least.

Obviously, those views did not last a year, and by the end of his term we were engaged in two land wars on the Eurasian continent, making efforts to stand up two democratic states in Iraq and Afghanistan, and faced with serious new challenges from a rising China and a nuclear-bound Iran.

But George W. Bush has not been the odd man out when it comes to such change.

When Bill Clinton took office, the signature issue was the domestic economy and, accordingly, realizing our limits internationally. By the end of the Clinton years, his secretary of state, Madeleine Albright, was describing the United States as “the indispensable nation,” and the administration had sent carriers to the Taiwan Strait as a warning to Chinese misbehavior and was taking the lead in a military intervention in the Balkans.

Even earlier, George H. W. Bush began his presidency expecting to focus his attention on managing the politics of the great power triangle of the Soviet Union, China, and the United States. What he wound up doing was helping manage the collapse of the Soviet state, dealing with the fallout of a China torn internally by the Tiananmen Square massacre, and cementing an unexpectedly unified Germany into the camp of the West. And in addition to invading Panama and removing the tin-pot dictator Manuel Noriega from power, Bush also led a coalition of hundreds of thousands from around the world to oust Saddam Hussein’s army from Kuwait after its surprise invasion of its neighbor in 1990.  By the end of President’s Bush term in office, this most “realist” of administrations was speaking about the creation of a “new world order.”

And, of course, the Obama administration has been gob-smacked by the world as well.  Much of the president’s first year in office was spent talking to the Chinese about new and profound ties between the United States and the Peoples’ Republic and attempting to create a new, more conciliatory relationship with countries of the Middle East. However, coming to terms with increasingly aggressive behavior on the part of the Chinese and an accelerating military build-up, the White House announced a new defense guidance document this past January which spells outs Washington’s intent to “pivot” more military resources to the Asia-Pacific region, and designed to reassure friends and allies that we will not let China intimidate them and change the balance of power in the theater.

Of course, before that can happen, the administration was counting on reducing America’s profile in the Middle East.  Yet a war to remove Qaddafi from power, a civil war in Syria, the so-called Arab Spring, and a potential conflict with Iran have frustrated their efforts to change America’s strategic focus.

In short, “stuff” happens and there is only so much an American president can do to prevent it from happening.

As the history above should remind us, every president since the Cold War’s end has gone to war and done so with no expectation he would do in those precise places before he took office.

The lesson is that we shouldn’t care what a candidate says he will do once in office but that we should also look behind those statements, assess the assumptions that guide them, and ask ourselves whether those principles make sense when new circumstances inevitably arise.

We should also come to some judgment about the character of the person sitting in the Oval Office who will be carrying out those principles potentially under the duress of too little time and not enough information.

We all want to know what a president plans to do during his four years as the nation’s chief executive.  However, the past suggests that, more than likely, what a candidate says before being elected will not necessarily define how his presidency in fact plays out. The world gets a vote, too.