From the Oval Office, U.S. President Barack Obama speaks on the phone with Iranian President Hassan Rouhani on Sept. 27, 2013.

President Obama’s halting, erratic, often contradictory response to the Islamic State’s emergence is a classic example how rigid ideology can distort reality. His unwillingness to acknowledge the developing threat, to prepare a counterstrategy before it metastasized, or to respond adequately to its growing success, all demonstrate the consequences when ideology triumphs over contrary evidence.

Mr. Obama has whipsawed between deriding ISIS (or ISIL, as the Islamic State was originally known) as “jayvee” terrorists, to insisting it be “degraded and ultimately destroyed” as a menace that cannot be reasoned with, while showing a jaw-dropping inability to characterize the conflict as a “war.” He has ordered airstrikes against Islamic State targets without many restrictive rules of engagement imposed on our forces elsewhere, but has simultaneously ruled out using U.S. combat arms to achieve that goal, even though nearly 2,000 American military advisers are currently in Iraq. Now, after mere weeks of sporadic air attacks, the president has “pivoted” away from the Islamic State threat, back to extolling his domestic economic accomplishments.

What is going on here with Mr. Obama? His sycophants attribute his passivity and detachment from reality to the subtlety of his intellect, and his ability to comprehend complex problems far beyond the inadequate capacities of his critics. This is almost certainly Mr. Obama’s view, narcissism being one of his strong suits.

The critics have numerous alternative theories, starting with assessing that Mr. Obama is all about politics and not at all about governance. His administration’s reckless disregard for legal and constitutional restraints reflects that being economical with the truth is now the White House’s standard operating procedure, as the Benghazi and Internal Revenue Service scandals and subsequent cover-ups exemplify. More exotic hypotheses also abound, from his parentage and heritage to his religious beliefs and fundamental motives.

Rather than indulging in pop psychology or conspiracy theorizing, we should seek the most straightforward explanation consistent with the evidence.

The real root cause, however, is ideology. The evidence is overwhelming that Mr. Obama is blinded by a worldview unfortunately far from unique in academic and leftist circles. Our university faculty lounges are overflowing with his ilk. He sees America’s place in the world as more problematic than beneficial and, therefore, concludes that a withdrawn, unassertive America is better for us and for the world. While most Americans believe this is looking at the world through the wrong end of a telescope, it is nonetheless the view of Mr. Obama and the professoriat generally.

The ideology affects Mr. Obama’s conduct as president (such as dealing with the Islamic State or Benghazi) by providing screens over his perception of reality that make it impossible for him to process information that contradicts his worldview. So automatic and rigid are these screens, they do not function by conscious choice, but are essentially automatic. Worst of all, they do not adjust even after repeatedly proving themselves counterproductive in dealing with the reality the average American sees clearly.

The effects of these screens over perception, and similar filtering mechanism were brilliantly described more than 50 years ago in Karl Deutsch’s classic “The Nerves of Government.” Deutsch explained how receiving, filtering, remembering and recombining communications flows was the essence of government, and that deciding which information was relevant and important, distinguishing it from the mass of other communications that could overwhelm individuals or institutions, was key to understanding decision-making. The filters that let some information through, but keep other information out of the critical of decision-making, are thus obviously central to understanding how Mr. Obama or anyone else ultimately makes decisions.

Screens come in many different forms, but preconceived ideologies are among the most powerful, since they reflect a person’s basic beliefs. To be continuously effective, however, feedback about the suitability of the information must include the ongoing capacity to adjust the screens to deal with actual reality, or ultimately the individual or the institution itself will perish. As Lord John Maynard Keynes once reportedly said, “Why, sir, when the facts change, I change my mind. What do you do?”

In Mr. Obama’s case, he does not change his mind, facts be damned. He does not have a feedback loop. His ideological screens remain firmly in place, increasingly disabling him from comprehending or dealing with international reality, dangerously exposing the United States now for almost six years. Still larger difficulties and threats loom in his presidency’s remaining two years, as our opponents seek to advance their agendas before Mr. Obama departs.

Critically, however, voters should learn the lesson that Washington needs leaders, in the White House and in Congress, whose experiences and values ground them in international reality, not merely derived from academic essays, staff briefings and abstract theorizing. Our November elections are a golden opportunity to bring exactly such people into the House and the Senate, and the 2016 presidential election will be even more important. If we fail to heed the lessons of Barack Obama, we have only ourselves to blame.

John R. Bolton, a former U.S. ambassador to the United Nations, is a senior fellow at the American Enterprise Institute. This article was originally published by The Washington Times.