Scientific Arguments


I recently read an interesting article on the role of science in debates over controversial issues, which got me thinking about the relationship between science and critical thinking.


As readers of Critical Thinking know, the concept that there exists a form of thinking distinct from intelligence and wisdom, one unique enough to be called “critical,” is a 20th century idea informed by the success of science as a human endeavor. This is why early instruction on how to think critically followed scientific principles, such as forming hypotheses, testing them, and drawing conclusions from the results.


At the same time, I’ve frequently made the case that critical thinking does not involve thinking like a scientist but rather that scientists are part of a culture and community that have found ways to think critically enough of the time to give us all the wonders of the modern scientific and technological age.


To understand what I mean, think about what scientists do when they come up with a hypothesis and put it to the test. This process is not about unearthing truths, but rather about constructing arguments just like the ones long-time LogicCheck readers have seen applied to non-scientific matters.


To take one example, for hundreds of years scientists believed that all combustible materials contained a substance called phlogiston that was released when the material is burned. Based on this theory, all burnable materials should become lighter when they combust and their phlogiston is released into the air.


This set of assumptions can be boiled down to the following informal argument:


Premise 1: Combustible materials burn because they contain a substance called phlogiston that is released when the substance is burned.

Premise 2: Phlogiston has weight.

Premise 3: When a substance with weight is removed from an object, that object becomes lighter.


Conclusion: All materials become lighter after they burn.


If you’re talking about wood or charcoal, these do indeed become lighter when they are reduced to ash. But eventually some scientists discovered certain metals that actually increased in weight after burning, which led to the conclusion of this argument being false.

Given that this is a valid argument, i.e., one in which accepting the premises requires you to accept the conclusion, then the falseness of the conclusion points to the likelihood that at least one of the premises is false.


While this problem could be solved by adding a novel new premise (like one that says phlogiston has negative weight), it became much easier to search for a new theory – i.e., a new argument – to explain how and why materials burn. This ultimately led to a new theory of combustion based on a chemical reaction of oxidation that turned out to be (1) valid (the premises led to the conclusion), (2) sound (the premises were true); and (3) accurate (the conclusion was not/has not yet been proven false).


The reason science has been so successful is that scientists work within a culture that rigorously tests arguments for strength and weakness and scrutinizes premises for truth and falsehood. Peer review, requirements that experimental data be confirmed through replication of the original experiments, and other techniques are all part of the process of analyzing the logical arguments underpinning every scientific proposal about how the world works.


When it comes to using scientific data to support one side or the other in a debate over a topic not entirely scientific in nature, this too boils down to creating logical arguments that can be tested for quality.


For example, that article linked above talks about a debate between proponents and opponents of gun control, each of which provided scientific studies to support their positions. To show the role science plays in those debates, here is one side’s argument rendered into now-familiar (hopefully) argument format:


Premise 1: Statistics shows that 70% of homicides in Illinois take place in Chicago.

Premise 2: Chicago has more legal gun restrictions than other parts of Illinois.


Conclusion: Legal gun restrictions do not reduce gun homicides.


Presuming premise #1 is accurate and based on scientific principles related to gathering and analyzing statistical information, then we can say that science is informing this person’s argument. But notice that this science is only serving as a premise in the argument, meaning the argument as a whole makes use of science, but is not arguing a strictly scientific point.


Remember that the first test of argument quality is validity, which requires us to accept the premises as true and see if we can still reject the conclusion. In this case, we can come up with many reasons why gun homicides might be high in Chicago (premise #1), even with the city’s strict gun control laws (premise #2). The fact that population density and poverty are much higher in Chicago than in more rural parts of Illinois, for instance, is a reasonable explanation for the seeming contradiction that powers this argument. It may also turn out that Chicago is an anomaly and that in other states gun control laws correlate with a decrease in gun deaths.


Notice that we were able to challenge this argument without proving one or more of the argument’s premises are false (the test for soundness). In other words, premise #1 might be based on the most air-tight scientific study ever produced, but that does not translate to the argument as a whole being based on similar scientific certainty.


This does not mean that science should be dismissed just because its main role is as a premise (or set of premises) of an argument. If similar scientific studies showed inverse correlations between gun laws and gun violence in many other states, that would certainly strengthen the argument that gun-control laws were ineffective, just as widespread studies showing reductions in gun violence in places with strict gun-control rules could be used to argue for the effectiveness of gun laws.


In either case, science plays a vital role in helping shore up an argument, but it should not be treated as a talisman that can be waved to show that one side is “following the science,” while their opponents believe in sorcery.

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