The videos posted by Jared Lee Loughner on YouTube at first appear to be a jumble of disjointed thoughts. He claims to be a “conscience dreamer” concerned with “English grammar structure” and “mind control” who wants to see the United States return to the gold standard. Yet Loughner expressed these wild ideas in an organized form: the logical syllogism.

A syllogism is a form of argument in which a conclusion is inferred from a set of premises. “All men are mortal. Socrates is a man. Socrates is mortal,” goes the famous Greek inference. In one video, Loughner offers syllogisms of his own, including: “If A.D.E. is endless in year, then the years in A.D.E. don’t cease. A.D.E. is endless in year. Therefore, the years in A.D.E. don’t cease.”

“Yeah, that’s him,” says Kent Slinker, when I read him some of Loughner’s syllogisms over the phone. “That kind of nonsensical, disconnected thinking.” Slinker, an adjunct philosophy professor at Pima Community College, taught Loughner in Introduction to Logic during the spring semester of 2010. Slinker’s impression of Loughner was that of “someone whose brains were scrambled.”

Loughner was a model student when it came to attendance—he always showed up on time to the twice-a-week class, at least before he dropped out toward the end of the semester. But in other respects, he was a mess. He didn’t perform well on tests. He would ask questions that didn’t make any sense. “His thoughts were unrelated to anything in our world,” says Slinker. One time, he handed in an assignment with geometric doodles instead of answers. Slinker also remembers that Loughner would have “exaggerated ‘Aha!’ moments just completely not connected to anything in class.” He was mentally checked-out. “He always was looking away, not out the window, but like someone watching a scene play out in his mind.”

Starting about halfway through the semester, Slinker says, he tried repeatedly to talk to Loughner one-on-one. “I wrote [on his test] saying, Please talk to me after class so we can discuss your performance and explore alternative assignments,” says Slinker. But at the end of class, Loughner would cast his eyes down and run out the door.

Eventually, Slinker and the chair of the philosophy department, David Bishop, who taught Loughner in a different philosophy class at the same time, discussed ways to get help for Loughner. But for the school to give a student special treatment, the student has to “self-identify” as having problems, says Slinker: “If we could get him to go to a testing center, then we could help him.” But they were never able to engage him enough to raise the subject.

In retrospect, there were no conventional warning signs, says Slinker: “I never sensed violence from him.” Asked whether Loughner ever brought up politics, Slinker says “never.” The class didn’t talk about current affairs. That said, Slinker did point students to political ads for examples of logical fallacies.

Slinker heard about the shooting of Rep. Gabrielle Giffords on Saturday while reading the Arizona Daily Star online. The news was especially shocking, considering that Slinker had also taught Spencer Giffords, Gabrielle’s father, in a philosophy class in the summer of 2009.

Slinker hit it off with the elder Giffords, who had handed the family tire company over to his daughter, so much so that Giffords invited Slinker to his 75th birthday party, where Slinker briefly met Gabrielle. “She was full of energy, full of life, always with a smile, very sincere,” Slinker remembers. As for Giffords Sr., says Slinker, “It was like, this is my long-lost friend and we’ve been separated by so many years.” Giffords gave Slinker a picture of his daughter with her husband and President Obama.

The odd thing about Loughner’s syllogisms is that they’re not far off from examples Slinker might use in class. “When you teach logic, you draw a distinction between truth and inference,” says Slinker. To illustrate that, a teacher might say, “If chickens could fly upside down, then George W. Bush would be president in 2098.” The statement isn’t true. It just serves as a premise from which to draw conclusions. The purpose, says Slinker, is “to show it’s the form of the argument rather than the content that’s the expression of validity.” But that only works when talking in the abstract. In real-world logic, premises matter. “If the premises aren’t true,” says Slinker, “all bets are off.”

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