How this tactic is supposed to work
This tactic depends on the notion that common sense is the basis of all correct reasoning. Users may even insist that science is really just common sense at heart. After all, back in 1854, T H Huxley said:
Science is, I believe, nothing but trained and organised common sense, differing from the latter only as a veteran may differ from the raw recruit.
Their line of argument is that if some complex scientific procedure comes out with conclusions that “defy common sense”, then the science must be wrong.
Why do people use this tactic?
People use this tactic when they don’t accept a scientific conclusion and want you to adopt their position. They either don’t understand the science, don’t want to understand it, or can’t muster good reasons for not accepting it. They promote the common sense explanation as temptingly simple, straightforward and authoritative. They try to distract you from delving deeper into the science by priming you to ignore it.
What’s wrong with this tactic
Basic common sense is often wrong. It tells you that the earth is flat, that heavy things fall faster than light ones, that the sun rotates around the earth, that you should throw water on an oil fire and that stress causes hypertension. Science tells us that all of those conclusions are wrong. Common sense doesn’t predict that you can melt ice by throwing salt onto it, that you can get sunburned on an overcast day or that two brown-eyed parents can have a blue-eyed child. Science can explain all those things. Huxley’s idea that science is highly refined common sense has a lot of support. But the “highly refined” part is very important. Physicist John Ziman puts it this way:
… it is in its conformity to the small print of common sense that science is distinctive. … Taken one by one, the cognitive norms that have to be satisfied – accuracy, specificity, reproducibility, generality, coherence, consistency, rigour, and so on – are all perfectly commonsensical: but they are seldom applied simultaneously outside science.
And philosopher Susan Haack expresses it like this:
… inquiry in the sciences is like empirical inquiry of the most ordinary, everyday kind – only conducted with greater care, detail, precision, and persistence, and often by many people within and across generations … … the evidence with respect to scientific claims and theories is like the evidence with respect to the most ordinary, everyday claims about the world – only denser, more complex, and almost always a pooled resource.
Common sense is often fine in very simple situations where there are few factors involved, and relationships between the factors are
linear. (Does the amount of sugar I put in my coffee influence the sweetness?). When things get complex, (
Will I get dehydrated from drinking coffee?), science is the way to go. When science and common sense seem to disagree, it’s a pretty safe bet that the science has it right.
What to do when confronted by this tactic
The perpetrator is hoping you’ll automatically defer to the common sense argument. Don’t. Be curious. Demand evidence. Ask if the scientific view differs from the common sense view. If it does, try to find out why scientists are confident in their conclusions despite the apparent contradiction. It’s always possible that the science
is wrong, but you can only say that after critically examining the scientific argument. Don’t accept the excuse that scientists are
scheming to cover up the truth, and look for
red flags such as
rooster syndrome,
cherry-picking and
apophenia.
Variations and related tactics
The appeal to common sense is similar to the appeal to common belief or
bandwagon fallacy (for example, that antibiotics will cure a cold). The appeal to common belief is a little less persuasive because common sense implies some logical validity, while it is well know that many common beliefs are wrong.
