Charles Seife is steaming mad about all the ways that numbers are being twisted to erode our democracy. We’re used to being lied to with words (“I am not a crook”; “I did not have sexual relations with that woman”). But numbers? They’re supposed to be cold, hard and objective. Numbers don’t lie, and they brook no argument. They’re the best kind of facts we have.

And that’s precisely why they can be so powerfully, persuasively misleading, as Seife argues in his passionate new book, “Proofiness.” Seife, a veteran science writer who teaches journalism at New York University, examines the many ways that people fudge with numbers, sometimes just to sell more moisturizer but also to ruin our economy, rig our elections, convict the innocent and undercount the needy. Many of his stories would be darkly funny if they weren’t so infuriating.

Although Seife never says so explicitly, the book’s title alludes to “truthiness” — the Word of the Year in 2005, according to the American Dialect Society, which defined it as “the quality of preferring concepts or facts one wishes to be true, rather than concepts or facts known to be true.” The term was popularized by Stephen Colbert in the first episode of “The Colbert Report.” The numerical cousin of truthiness is proofiness: “the art of using bogus mathematical arguments to prove something that you know in your heart is true — even when it’s not.”

Seife emphasizes that numbers impress us. They carry authority. Joe McCarthy, for example, didn’t simply allege that the government was infested with Communists; he held up a sheaf of papers and claimed it contained the names of 205 members of the Communist Party working in the State Department. The specificity of the accusation made it seem more believable. So what if the number soon went up to 207, then shrank to 57 a day later when McCarthy wrote to President Truman? What mattered is that the numbers intimidated McCarthy’s critics. As it turned out, he never had any list and couldn’t identify a single Communist working in the State Department. None of that stopped him from rising to national prominence on the back of his numerical lies.