It is Christakis who "should be deeply ashamed."

This is kind of shameful.  For Christakis.

In 1347, Jews were blamed for bubonic plague. In the 1990s, gays were blamed for HIV. In 2020, immigrants are blamed for COVID. The weak-minded desire to blame “outsiders” for epidemics goes back millennia, as discussed in #ApollosArrow.

And so this man should be deeply ashamed. https://t.co/o683VefGCp

— Nicholas A. Christakis (@NAChristakis) July 15, 2021

Christakis is an interesting academic with interesting ideas.  But he is also susceptible to Mandarin Class ignorance, making arguments based on performative signaling rather than based on evidence, reason and logic.

In this instance Ted Cruz is making a simple empirical argument.

In South Texas, we’re seeing #COVID positivity rates rising and it’s a direct result of illegal aliens being released into communities. 

The more extended argument would be something like:

Illegal aliens have a higher rate of infectious Covid-19 than does Texas.  When we catch them illegally crossing the border and then release them into Texas communities, they cause an increase in Covid-19 infections.  The increase in Texas infection rates is due to the policy of releasing infected illegal aliens into Texas communities.

It is a simple empirical argument.  All Christakis needs to do to refute, or at least call into question the argument, is show any of the following:

• Illegal aliens do not have higher rates of Covid-19 infection than already exist in Texas.
• Communities where illegal aliens are released do not subsequently have higher rates of infection.
• Texas does not have a rising rate of Covid-19 infections.
• The rate of Texas infection increase is greater than the increase in illegal alien releases.
• That the appearance of an increase in Texas infection rates is due to some other cause (for example, increased testing.) 

Those are Classical Liberal, Age of Enlightenment responses to Cruz's claim.  Yes, it requires a little work.  In thirty seconds of googling and binging I find that this argument was in the news in March of this year.  Back then, the claimed illegal alien infection rate was 6.6%.  But Cruz is making the claim in July that the illegal alien infection rate is higher now than that in Texas.

Which is where you immediately encounter the whole measurement and testing issue.  An infection rate comparison is only meaningful if you compare like-to-like.  If Texas randomly tests 10,000 residents in the week of July 12th and, using the same test, randomly tests 10,000 border crossers, then their respective infection rates can be usefully compared.

But if they don't use the same test, or not the same time frame, or it isn't random, then the comparisons become increasingly suspect.  If your infection rate is based on testing people who are admitted to hospital versus those randomly selected in public, then of course you are going to have different rates of infection.  

I am not finding readily comparable data. 

At a national/regional level, and using unaligned testing methodologies, Cruz does seem to have an argument.  On July 11th, the test positivity rate in Mexico is 33.3%.  In Texas, on the same (closest) date, July 9th, the test positivity rate was 4.4%.  But Texas's rate is based on 401,000 tests and Mexico's is based on 18,000 tests, suggesting that there is a major methodological difference in testing.

The point is that Christakis could have done a little work and made a counter argument based on data.  My suspicion is that if he spent ten hours researching the question he would have had to end up acknowledging that Cruz's argument cannot be either sustained or refuted because the data is not robust enough to do so.  

Instead, Christakis takes the lazy way out by making a logically fallacious and inherently ad hominem attack on Cruz.  It follows the form:  Cruz is making an argument about illegal aliens.  Other people in the past have also and erroneously made arguments about foreigners.  Therefore Cruz's argument must also be false. 

This is insulting to the reader's intelligence as well as insulting to Cruz and demeaning of Christakis's reputation as a public intellectual.

It is even worse because of Christakis's framing of the two historical counter-examples.  First he frames it as "blaming" when in many instances, it was observing.  

In the plague example, medieval Europeans observed (or blamed) that outbreaks of plague seemed to follow merchants on their trade routes, starting with Genoese merchants coming from the Black Sea area.  Jews, as merchants, were natural suspects.  But who else was blamed?  It wasn't just Jews or Genoese.  From Wikipedia.

Renewed religious fervour and fanaticism bloomed in the wake of the Black Death. Some Europeans targeted "various groups such as Jews, friars, foreigners, beggars, pilgrims", lepers, and Romani, blaming them for the crisis. Lepers, and others with skin diseases such as acne or psoriasis, were killed throughout Europe.

Christakis wants to tar Cruz with anti-semitism but in order to do so, he ignores the reality that the societal stress of losing 20-30% of your population caused people to blame many groups, most of them having some link to travel.  And that that linkage was valid.  How people responded to their correct causal observation was tragic but the observation that the Black Death was carried across borders by merchants, sailors, travelers and others was true.  

Second, Christakis seems to be wanting to tar Cruz with homophobia by creating a parallel where "gays were blamed for HIV."

But that is not what happened as those of us old enough to have lived through the HIV crisis and young enough to remember can testify.  There was immense uncertainty verging on panic when the potential scale of the scourge became apparent.  People were dying left, right, and center for no clear reasons.  

The cascade of association went from gay to drug users to African-Americans.  I.e. these were the groups who were quickly identified as being especially susceptible for unknown reasons.  I don't recall that gays were ever widely "blamed" for HIV, they were merely associated with it.  People feared to be closely associated with gays for some period of time because the nature of transmission was simply not well understood.   I recall at our church, a very gay receptive congregation, there was, in the space of just a few weeks, a large conversion to taking the Eucharist by intinction of the wine rather than by sipping from the cup.  

And then there is "The weak-minded desire to blame “outsiders” for epidemics."  This is the indirect means of accusing Cruz of being a xenophobe.  But again, we have already been down this path.  Despite the early denials of the Mandarin Class, Covid-19 was definitely of foreign origin and quite possibly man-made.  When Trump ordered very early suspension of foreign travel, he was widely mocked and accused of xenophobia.  It was only later acknowledged that the travel restrictions likely slowed the spread of Covid-19 in the US. 

Christakis's invocation of the Black Death and HIV and Covid-19 are both historically strained and seem to be used in order to tar Cruz as an anti-semite and as a homophobe and as a xenophobe.

Is Cruz making a good argument?  It is an empirical question.  There is a logical basis for the argument but it rests in the end on empirical evidence.  Either illegal aliens released into the community are driving an increase in Covid-19 infections or they are not.  The data should tell us.  

 Christakis betrays his public intellectual status by failing to acknowledge that Cruz is making a plausible empirical argument and by failing to refute that argument with evidence that it is wrong.  Christakis betrays his public intellectual status by stooping to historically inaccurate (or incomplete) analogs deployed in an ad hominem fashion. 

It is Christakis who "should be deeply ashamed."