14. Informal Fallacies - Presumption Part 2

 

Summary

The second session on fallacies of presumption covers the oversimplification / reduction subgroup, making a complex issue look simpler than it is by focusing on a limited aspect of it. Five fallacies are presented.

1. False dichotomy (faulty dilemma / bifurcation / excluded middle)

Oversimplifying by reducing the available options, usually presenting two choices as the only choices. Structurally it mimics a valid disjunctive syllogism ("either P or Q; not P; therefore Q"), but it is fallacious when the either/or premise is false because other options exist. The number of options need not be two, only fewer than the real possibilities. Examples: "either evolution is true or creation is true"; "you said you'd never vote for Trump, so you must be voting for Biden" (ignoring third parties or not voting).

2. Nothing-but (reductive) fallacy

Treating one aspect of a thing as the whole of it, "X is nothing but Y", when the thing is actually more complex. Examples: "man is nothing but an animal" (true that he is an animal, but it ignores what distinguishes humans); "thoughts are nothing but electric impulses in the brain" (behaviorism); "taxation is theft."

3. Category mistake

Confusing kinds, types, or natures, imposing the principles of one category on something in a different one (an apples-to-oranges error). It often confuses disciplines and their methods (using math to settle history) or roles and relationships (prescriptions vs. descriptions). Examples: "prove to me mathematically that there was a Civil War"; "what does red smell like?"; "what happened in the moments before time began?" (there is no "before" without time).

4. Argument from the beard (continuum / sorites / line-drawing / bald-man fallacy)

A fallacy about matters of degree: arguing that because you cannot identify the precise point where one extreme becomes another on a continuum, there is no difference between the extremes (when does stubble become a beard?). The assumption, that summing small differences never yields a big one, is false: one is clearly not one million. The larger the spread, the more fallacious the argument. Examples: "everyone is more or less good and bad, so don't call Stalin evil and Mother Teresa good"; "a single hair won't make me bald, so I'll never go bald."

5. Fallacy of moderation (golden mean)

Assuming the answer always lies in the middle between two extremes, the opposite error to the false dilemma. The correct conclusion depends on the specific premises: sometimes moderation is right, sometimes an extreme is. Unlike Aristotle's virtue (a mean between vices), truth is not a compromise. It appeals psychologically to those who want to avoid conflict and appease both sides. Example: pushing a reluctant skydiver out at 2,000 feet as a "compromise", worse than either original option.

Where this leads

The next presumption session moves on to the unjustified assumptions subgroup, with several more videos still to come.