Never mind how the mind works.

For many of the audience members shoehorned into 17 Logan Hall, the more pressing question was whether the sound system worked on Oct. 20, when Stephen Pinker, director of the Center for Cognitive Neuroscience at MIT, explained to the crowd “How the Mind Works.”

The lecture was interrupted twice as technicians and Penn Humanities Forum staff tried to figure out how to make Pinker audible throughout the hall, a problem exacerbated by the whir of slide-projector fans. And many of those wishing to attend were turned away -- the result of several psychology professors’ requiring their classes to attend, according to Penn Humanities Forum Associate Director Jennifer Conway.

Those lucky enough to get in and hear the speaker were treated to an entertaining explanation of the “computational theory” of the mind. The heart of the theory is that the brain, like a computer, is an information-processing device. However, “The computer is serial, while the brain is massively parallel,” he said.

The computational theory, Pinker said, answers some nettlesome questions better than any other theory.

One of those questions is “What is intelligence, and how can a hunk of matter be intelligent?” Pinker, to illustrate the point, used a passage from William James’ writings that drew a distinction between Romeo’s attraction to Juliet and iron filings’ attraction to a magnet. The human mind can set goals (in this case, kissing Juliet) and use inferences based on already-received information (there’s a wall separating Romeo from Juliet; therefore, in order to kiss Juliet, Romeo must scale the wall) to reach those goals, and it is this ability that is the essence of intelligence.

He also noted that a number of seemingly irrational behaviors, such as romantic love and disgust, are actually sensible defense mechanisms that protect people from future harm. These behaviors, he said, originated millions of years ago, when humans spent all their time hunting and gathering food, and despite changes that have made some of them counterproductive, there is still a rational basis for them.

In a post-lecture reception at the American Philosophical Society library, Pinker elaborated on one of the points of his lecture, which was that the mind also is nimble enough to devise ways to protect itself against its own worst tendencies.

“Much of what we consider progress is the setting up of defenses against ourselves,” he said as he refused a tray of hors d’oeuvres, thus delivering himself from the evil of consuming too much fatty food. “For instance, constitutional democracy, with its checks and balances, is an elaborate defense mechanism against the human tendency to abuse power.”

In a post-reception exchange with History and Sociology of Science Professor Charles Rosenberg, Pinker defended his position against charges from Rosenberg and audience members that his research is fraught with political implications.

“It’s not necessarily inevitable that everything we find out about human nature will be fraught with political and moral baggage,” Pinker said. “We once thought that way about cosmology -- the question of whether or not the earth revolved around the sun had great moral weight. But we were confused then, and we’re confused now when we do the same thing with questions about human behavior.”