June 1995 LSAT Section 2 Question 3

A certain strain of bacteria was found in the stomachs of ulcer patients. A medical researcher with no history of ulc...

Ceci_Perez on May 6, 2021

Is the takeaway here that a strong correlation between the absence of a certain factor and the absence of another factor in a representative sample provides evidence that a causal relationship exists?

I understand that one way to weaken a causal argument is by providing examples of an effect in the absence of an alleged cause (or vice versa). In the same vein, is it safe to say that you can strengthen a causal argument by showing there's a strong correlation between the ABSENCE of an effect and the absence of a cause? In other words, in a large, representative sample, can we say that: no cause + no effect = a causal relationship exists? (Sorry for using caps! Not meant aggressively, just for emphasis and I can't italicize here)

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Emil-Kunkin on June 23 at 06:30PM

I wouldn't exactly say that, but I would phrase it as since we are trying to support the idea that X causes Y, showing that many people who lack Y also lack X helps show this. This is because we have a correlation because the presence of X and Y, but that could be purely coincidental. The fact that one thing is absent when another thing is also absent is not useful on its own, but it can rule out the possibility that a supposed correlation between the presence of those two things is spurious.