The Houston Chronicle: "Half of Ted Cruz’s political claims are false, PolitiFact reports" and "Ted Cruz v. PolitiFact: Whose pants are on fire?"

Joanna Raines of the Houston Chronicle wrote a story on March 28 attempting to report PolitiFact's assessment of Sen. Ted Cruz (R-Texas).

The headline and text of Raines' story hinted at a fallacious reasoning.

Raines' story was titled "Half of Ted Cruz’s political claims are false, PolitiFact reports."  It's somewhat natural to take PolitiFact's report card-ish stories along those lines, but the fact is that PolitiFact doesn't rate enough statements to draw general conclusions about political figures.  Compounding the problem, PolitiFact offers no hint at all that its system includes controls for selection bias.  Compounding the problem further, PolitiFact often reaches questionable conclusions with its ratings.

Raines published a follow up story on March 29, titled "Ted Cruz v. PolitiFact: Whose pants are on fire?"  That story implicitly acknowledged the last problem on the preceding list.  Raines offered a brief and reasonably fair account of the substance of Cruz's disagreements with PolitiFact.

Unfortunately, the second story contains a strong hint that Raines continues to reason fallaciously:

To navigate these muddy waters, we’re asking for you to weigh in. Cruz’s office has defended itself against PolitiFact’s claims, and we’re going to let you determine who deserves the “pants on fire” rating, Cruz or PolitiFact?

Ugh.

A survey of public opinion serves very poorly as a measure of truth in most instances.  The flawed reasoning goes by the Latin name argumentum ad populum, also known as the fallacious appeal to the people or the appeal to popularity.

Our guide to the truth should remain the state of the evidence, supplemented by consideration of the arguments pro and con.

Raines' first story helped underscore the truth of one of our longstanding criticisms of PolitiFact:  Publish "report cards" for candidates and many readers will assume that the results say something about the candidates unless the fact checkers explain the error behind that assumption.