Dictionaries define intelligence with such synonyms as: comprehension, judgment and perceptiveness. One might ask, does that also mean we are rational?
Do we pose questions and seek evidence that proves or disproves the conclusion? Rationality suggests synonyms such as logical, reasonable, sensible and coherent.
But, are we truly rational?
For example, when Galileo argued that our Earth circled the sun rather than the reverse, he was put under house arrest for the remainder of his life. This assertion contradicted beliefs held by powerful people whose beliefs mattered more than truth. That Galileo had evidence didn't matter.
In the face of overwhelming scientific evidence, flat-Earth folks have believed — and some still do — that the Earth is flat. One might understand that argument before evidence was available to prove otherwise, but even today?
After Hawaii provided proof that Barack Obama was born in that state, the "birthers" persisted in the belief that he is not an American citizen. Our current president was one of the first to parrot this nonsense. Facts are apparently of little consequence when contradicted by the will to believe.
Although no evidence has been offered to support the contention, many Americans seem convinced that the past election was riddled with fraud. The will to believe can be stronger than evidence.
Are we humans intelligent? The answer is yes. Are we rational? That gets only a qualified "sometimes."