April 12, 2007 10:34AM # Does the Public Understand Causality? By [Michael F. Cannon](https://www.cato.org/people/michael-f-cannon) --- SHARE Thankfully, Ezra Klein [admits](http://ezraklein.typepad.com/blog/2007/04/cannon_and_tann.html) that an *L.A. Times* [op/​ed](http://www.latimes.com/news/opinion/la-oe-tanner5apr05,0,2227144.story?coll=la-opinion-rightrail) I co-authored with Mike Tanner is not inaccurate. (Phew!) However, he still accuses us of misleading readers. Klein writes, “The \[Levy and Meltzer\] study says the evidence *suggests* \[that health insurance improves health\], but causality is difficult to discern” \[emphasis added\]. Seems to me that the Tanner/​Cannon claim to which Klein objects — that Levy and Meltzer “were unable to establish a ‘causal relationship’ between health insurance and better health” — positively *flows* from Klein’s characterization. So tell me again what the fuss is about? Ah, yes. Klein believes that our characterization misleads the reader. He presumes that “most readers understood that passage to say that the researchers couldn’t establish a relationship between health insurance and health.” Note that Klein drops the word *causal*. That’s because he assumes that readers of the *L.A. Times*’ op/​ed page would equate “were unable to establish a ‘*causal* relationship’ ” with “were unable to establish *any* relationship.” That is, either readers of the *L.A. Times*’ op/​ed page don’t know what the word *causal* means, or they have a blind spot for it when it appears in print. (I do not exaggerate. Klein writes explicitly of “the public’s unfamiliarity with the concept of ‘causality.‘”) That assumption about readers of the *L.A. Times*’ op/​ed page means that Klein is not denouncing what Tanner and I actually wrote (note the substantial agreement above), but what he assumes was the readers’ misinterpretation of what we wrote. Perhaps he should direct his ire at them. Two conclusions are possible: 1. Klein, Tanner, and I all have a dim view of readers of the *L.A. Times*’ op/​ed page. Tanner and I are trying to deceive them, while Klein is their savior. 2. Klein is the only one with a dim view of the readers of the *L.A. Times*’ op/​ed page, and he is willing to slight them if that’s what it takes to defend the idea of universal coverage. Whatever the case, it’s nice to think that if readers of the *L.A. Times*’ op/​ed page do understand causality, then any attempt Tanner and I made to deceive them would have failed, and Klein would have nothing to criticize. (Another oddity…Klein accuses [my initial response](https://www.cato.org/2007/04/09/does-expanding-health-insurance-affect-health/) of avoiding his chief criticism regarding causality by “focus\[ing\] mainly” on the issue of cost-effectiveness. Actually, I spent 600 words on his main criticism and only 131 words on cost-effectiveness. *Que peut-on dit dire?*) ##### Related Tags [General](https://www.cato.org/general), [Health Care](https://www.cato.org/health-care) [![Creative Commons License](/build/cato_2020/images/creative-commons.svg)](http://creativecommons.org/licenses/by-nc-sa/4.0/) This work is licensed under a [Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License](https://creativecommons.org/licenses/by-nc-sa/4.0/).