Arguing by Assumption: The Enthymeme
Many arguments we make in daily life are incompletely stated, or less than completely certain, in structured debates and in informal discussions.
Some such arguments are called Enthymemes, arguments in which one of the premises, or the conclusion, is left omitted but implied and needed for the argument to follow.
Why leave these out?
It depends on the situation, and upon the shared understanding of those involved in the discussion.
Generally, one part of an argument may be left out because it is assumed by both and doesn’t need to be stated, though these parts will need to be teased out by a third-party analyst of the argument to determine fully what is being argued.
This can be an intellectually honest form of argument, as follows with a few examples.
I’m using standard form deductive syllogisms, or conditionally certain three-part arguments with two premises and a conclusion, for ease of presentation here. First below is a 1st order, or unstated major premise, argument:
- The Magnus is a mutant.
- So the Magnus is radioactive.
With the major premise being:
- All mutants are radioactive.
This next has a hidden minor premise, or 2nd order enthymeme.
- Not giving the proper homage to the Nine Who are One will endanger all our lives.
- So we should not fail to give proper homage to the Nine.
With the hidden premise given as:
- The Nine would wish us to do that which preserves our lives.
Finally, we have one in which the conclusion is left unstated, of the 3rd order:
- We must eliminate all freakishly powerful dangers.
- The Mirus is a freakishly powerful danger.
It’s not hard to see where this one will go… The conclusion, though unstated, should be obvious.
In some situations where one of the arguers is less than intellectually honest, and when the assumptions are NOT shared, or should be fully expressed, an argument of this sort may be used to confuse matters — as a rhetorical fallacy — as a tactic that obscures the meaning of an argument and makes misdirection and confusion easy.
This happens when the aim intended is thwarting the goal of honest critical discussion. I’ll provide an example of this as a fallacy, this one from a hypothetical creationism/evolution debate in which the major premise is obscured:
- No fossil meeting my (unattainable) criterion as transitional has ever been found,
- So there are no transitional fossils, so evolution is false.
But here is the missing major premise, NOT shared or expressed — but assumed by the creationist:
- To count as transitional, a fossil must be an impossible, half-formed monstrosity combining unlikely features of dissimilar species or ‘kinds,’ like a lizard/bird hybrid with incomplete, useless wings… (or a crocoduck)
‘Enthymeme’ is also used to refer to Maxims, or probabilistic arguments, such as those used in inductive reasoning or in informal argumentation where language is bound up with an argument’s content, and the conclusion follows from the premises more or less strongly, but debatably depending on the audience.
One such maxim may be “Present-day Continental philosophy is not credible,” which could elicit different responses and have differing levels of credibility depending on the philosophical schools of those involved.
As can be seen, some of the very same sort of statements used in ordinary argumentation can be fallacies, and indeed, when informal, their fallaciousness depends on their misuse as argument strategies, not so much the the structure of the argument — violations of procedure rather than logical form.
Many fallacies are not always such, but even otherwise good arguments, when they are put to that use, are pure argumentative poison.
- Philosophical Fallacies in Political Reasoning (kingsofdeceit.wordpress.com)
- Asserting and Arguing (maverickphilosopher.typepad.com)
- The Schadenfreude Objection to John Stuart Mill (ajrogersphilosophy.wordpress.com)
- On Argument and Why Men Should Never Show Their Legs in Public (louisrose.com)
- A Common Fallacy In Global Warming Arguments (wmbriggs.com)
- Composition: Formal or Informal Fallacy? (maverickphilosopher.typepad.com)
- Aristotle’s Three Musketeers: ethos, logos, pathos (justwriteonline.typepad.com)
- An Interview with Don McLeroy, Part IV (theness.com)
- on the reality of sherlock holmes etc (3ammagazine.com)