Apologia

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False dichotomy fallacy (again)

APOLOGIABy Hendrik van der Breggen
(The Carillon, July 15, 2010)

False dichotomy fallacy (again)
The false dichotomy fallacy (a.k.a. false alternatives fallacy) is a mistake in reasoning which occurs when we assume that there are only two options, when there are actually more, yet we go on to conclude that one particular option (of the two options) must be true.

Here’s an example: Let’s say I argue that everything is either black or white, but X is not black, therefore X must be white. This is a false dichotomy fallacy because the truth of the matter is that there are shades of grey as well as shades of red, orange, green, etc.

Last time I presented some examples of the false dichotomy fallacy which are problematic with respect to ethics (i.e., physician-assisted suicide, embryonic stem cell research, experimentation on frozen human embryos). This time I will present an example that is problematic with respect to epistemology (i.e., theory of knowledge).

Consider this claim from New Testament scholar D. A. Carson (Carson doesn’t believe this claim, he merely and correctly presents it as a fallacy incurred by some thinkers he calls “hard postmodernists”): “Either we human beings can know something absolutely, perfectly, exhaustively…or we human beings can at best glimpse some small perspective on something or other without any mechanism for discovering whether our perspective is an important part of the whole, a distorted view of the whole, or a skewed view of the whole….”

In other words, either (a) we can have certain, infallible, and complete knowledge of X, or (b) we should embrace skepticism concerning knowledge of X—i.e., we can’t know X truly.

Clearly, we do not and cannot have certain, infallible, and complete knowledge (because we are not God). So, or so the (fallacious) argument goes, we should be skeptical. We cannot know. End of argument.

Significantly, however, a third alternative is missing. Consider (c): We sometimes can and do know X truly, albeit fallibly and non-exhaustively.

To support the truth of the missed third option, let X = a wooden pencil. Surely, I can know truly that there’s a wooden pencil on my desk even though I don’t know everything about the object I’m calling a wooden pencil. Surely, I can know truly that there’s a wooden pencil on my desk even though I don’t know what type of wood it’s made of, what sort of hardness the lead is, what the exact thickness of the lead is, what the chemical composition of the yellow paint is, etc.

I know that the object in question is a wooden pencil by carefully observing its salient features: It’s about 7 inches long, yellow, wooden, thin like other pencils, plus has a blackish lead, brownish eraser, shiny metal band.

Of course, I could be mistaken. The object could be a plastic mechanical pencil built to look like a regular wooden pencil. But the fact remains that when I examine the object, I see that it’s a regular wooden pencil. In fact, when I re-check the evidence, I know it’s a regular wooden pencil.

Of course, I should admit that it’s logically possible that I’m hallucinating or in a Matrix—clearly, I don’t have absolute certainty. However, I also know that mere logical possibility (such as the moon might be made of cheese) isn’t sufficient grounds for actually taking seriously that the possibility may be true (that the moon is in fact made of cheese). That is, I know that mere logical possibility (i.e., a description that isn’t internally contradictory) isn’t the same as epistemic plausibility or probability (i.e., an evidence-grounded knowledge claim).

Of course too, when I look at X’s features, I also don’t know exactly how I know that X is a wooden pencil. Presumably, light reflects off the pencil’s surfaces onto my retinae, which then send a neurological message to my brain, which in turn let’s me see the pencil plus classify its properties. Whether this story of how I know is correct or not, I know the following philosophical fact: Even though I don’t know how I know the pencil, I know that I know the pencil. That I know is more basic, knowledge-wise, than understanding how I know.

Thus, it’s reasonable to think that I sometimes can and do know X truly, even though my knowledge isn’t exhaustive, isn’t perfect, and isn’t absolute. I know some things truly, even though I’m fallible and limited.

Happily, via the doing of various types of critical thinking—e.g., the sciences, history, New Testament studies, philosophy, etc.—I can know even more things, or at least come to a reasonable belief concerning those things, albeit fallibly and in a limited sort of way.

The false dichotomy fallacy—it sometimes takes careful thinking not to be fooled by it.

(Hendrik van der Breggen, PhD, teaches philosophy at Providence College, Otterburne, Manitoba, CanadaThe views in this column do not always reflect the views of Providence.)

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