Follow the Science


Given how much we are urged to “follow the science” when making important decisions about health, the environment, and other matters (decisions with political as well as scientific ramifications), it’s important to keep in mind the role science is actually playing in debates we have over such issues.


As mentioned last time, scientific evidence can serve as extremely powerful premises that support a conclusion within an argument. But the use of scientific evidence does not necessarily mean the conclusion follows from those premises with the kind of certainty we associate with science.


Arguments that water freezes at zero degrees Celsius or that 2 + 2 will always equal four seem pretty air-tight, which is why we often take arguments based on scientific studies or numeric information more seriously than ones based on something else. Policy debates, however, are usually over what choices we should make to best deal with an unknown future and since science cannot tell us with certainty what tomorrow will bring, we need to able to analyze the quality of arguments for or against particular positions and not just assume science provides obvious answers.


To pick a contemporary example, should people who have been vaccinated against COVID-19 still wear masks? This article from the New York Times argues that they should, as do current recommendations from the Centers for Disease Control (CDC).


One would think that once you were vaccinated against the virus, you would no longer need to take the kind of precautions people have been living with for months, including wearing masks and keeping a safe social distance from other people. An argument for this position would look like:


Premise 1: People should wear masks and practice social distancing in order to avoid being infected by coronavirus.

Premise 2: Once you are vaccinated, your chance of being infected by coronavirus reduces enormously.


Conclusion: Once you are vaccinated, you no longer need to wear a mask or practice social distancing to avoid being infected.


By now, I hope you can see that this argument is not valid in that reducing chances of infection does not mean risks have been entirely eliminated (meaning you can reject the conclusion, even if you accept the premises – the definition of invalidity). More significantly, however, the first premise of the argument ignores that a primary reason to wear a mask is not just to avoid catching the virus from someone else, but also to avoid spreading the virus to other people if you have it. Therefore, this argument is also unsound.


The Times article is based on a different argument, one which says:


Premise 1: People who have been vaccinated might still be able to spread coronavirus, even if vaccination reduces their chances of getting sick if exposed.

Premise 2: Masks and social distancing slow the spread of infection from one person to another.


Conclusion: People who are vaccinated should continue to wear masks and social distance to avoid infecting others.


Unlike the first argument, this one is valid in that accepting the premises requires you to accept the conclusion. But in order for it to also be sound, both premises need to be true, or at least statements a reasonable person would accept as likely to be true.


Presuming most reasonable people buy into Premise #2, the soundness of this argument rests on whether or not it is also reasonable to accept Premise #1.


This is the premise in which science plays a major role, and the Times article makes a compelling case that people who have been vaccinated might still be able to carry and spread the virus, even if vaccination makes it unlikely they will get sick from it. I won’t get into all of the discussions of what happens inside the noses of people exposed to COVID 19, but I will note that the Times - citing and linking to different scientific sources - provides substantial information to support the likelihood of Premise #1 being true.


Interestingly, acknowledgement of how much we don’t know about the spread of the virus (which appears in both the Times piece and CDC material) actually strengthens Premise #1 (and thus the argument) by pointing out we are dealing with likelihood rather than certainty (thus the use of the term “might” in that premise). But since the stakes over this issue are life-and-death, we need to take this argument extremely seriously, even if there is a chance Premise #1 might turn out to be wrong (which would make the entire argument unsound).


A couple of other points to consider before giving the Times a dumbbell award:


(1) Even through the Times piece is a news article, rather than an editorial, it is arguing a position, rather than just reporting facts. Journalists I have talked with about logic-checking the news often bristle at the notion that they are in the argumentation (and thus the persuasion) business, but if something you read in the newspaper contains premises leading to a conclusion, that means it includes arguments and not just bunches of data.


(2) Because Premise #2 focuses on mask wearing and personal social distancing, it is relatively easy to accept the conclusion and behave accordingly since the steps you need to take – while annoying and inconvenient – do not necessarily lead to other forms of harm. If the Times used this same argument to call for continued lockdowns or school closings even after substantial numbers of people have been vaccinated, they would have to add additional premises to show that measures already causing economic havoc and personal and family hardship (even trauma) are worth the effort.


As you might guess, the Times argument makes all the right moves, which is why I’m awarding it the coveted five dumbbells, indicating that while it is good to “follow the science” in terms of taking it seriously when it is used to form premises of an argument, it is just as important (if not more so) to “follow the logic” to make sure those scientific premises lead to a reasonable and acceptable conclusion.



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