In 2003, the conservative columnist Charles Krauthammer diagnosed a new affliction in some of George W. Bush's fiercest critics. He described the condition as "the acute onset of paranoia in otherwise normal people in reaction to the policies, the presidency -- nay -- the very existence of George W. Bush." He called it Bush Derangement Syndrome.

BDS, at least in the examples Krauthammer gave, was mostly about Bush's policies. Howard Dean, for instance, wondered whether Bush was suppressing the release of the 9/11 report because "he was warned ahead of time by the Saudis." Barbra Streisand speculated that the war in Iraq was partially motivated by the influence the logging industry wielded in the Bush administration.

Bush Derangement Syndrome was, in other words, a function of 9/11 and the Iraq War: it was an effort, often misguided, to explain how the worst terrorist attack in American history happened, and why the most puzzling war in American history was launched.

Obama Derangement Syndrome is different. It isn't so much paranoia about President Obama's policies as it is paranoia about the man himself — that he is, in some fundamental way, different, foreign, untrustworthy, even traitorous. What's odd is that it is attached to a president whose presidency has been, in almost every respect, conventionally liberal. Bush Derangement Syndrome sought extraordinary explanations for extraordinary events; Obama Derangement Syndrome seeks extraordinary explanations for an ordinary presidency.

Rudy Giuliani's now infamous remarks fit the pattern. "I do not believe — and I know this is a horrible thing to say — but I do not believe that the president loves America," the former New York City mayor said said Wednesday. "He doesn't love you. And he doesn't love me. He wasn't brought up the way you were brought up and I was brought up through love of this country."

Giuliani's remarks were condemned in most circles — but not all. Louisiana Governor (and 2016 hopeful) Bobby Jindal said Giuliani "should have used different phraseology." You've heard of non-denial denials? That's a non-endorsement endorsement.

Gov. Scott Walker — another 2016 hopeful — refused, when asked, to say whether Obama loves his country, and then sparked a mini-furor when he said he didn't know whether he thought Obama was a Christian (his spokesperson later said Walker was objecting to the line of questioning, and does believe Obama to be a Christian).

All this is simply the latest iteration of long-running Republican suspicions about Obama's otherness. In the run-up to the 2012 election, for instance, Newt Gingrich mused, "What if [Obama] is so outside our comprehension, that only if you understand Kenyan, anti-colonial behavior, can you begin to piece together [his actions]?"

Giuliani, Jindal, and Gingrich are simply echoing a political movement that has never been persuaded that Obama is actually American. As Jenée Desmond-Harris notes, a 2014 Economist/YouGov poll found that "a full 23 percent of Americans said they still believed it was possible that Obama was born outside the United States ... Among Republicans, the numbers were even more shocking: two thirds disagreed with the statement that the president was born in the states."

What is so odd about Obama Derangement Syndrome is how thoroughly within our comprehension Obama's presidency actually is. His path to power — Harvard Law School, Illinois legislature, US Senate — is unremarkable. His White House is stocked with veterans of the Clinton White House and the Democratic congressional leadership. His policies are conventionally center-left. His vice president is literally Joe Biden. No one loves America more than Joe Biden.

But then, that's why Obama Derangement Syndrome is different than Bush Derangement Syndrome: it's not really about Obama's presidency. It's about Obama himself. It's about his blackness, his father's foreignness, his strange name, his radical pastor. Obama's presidency is in many ways ordinary, but the feelings it evokes are not. There is something about seeing Obama in the White House that deeply unsettles his critics. Obama Derangement Syndrome rationalizes those feelings.

If it's really true that Obama doesn't love this country, if it's really true that his birth was a conspiracy and his ideology is baroque, foreign, and hateful, then the discomfort some Americans feel when they look at Obama is justified — it's a kind of patriotic spidey-sense. The alternative explanation — the one that looks at why Obama makes some Americans so much more uncomfortable than, say, Joe Biden — requires a much harder conversation.