Welcome (or welcome back) to this Daily Kos series discussing logical argument! For now I'm writing these diaries on Mondays, Wednesdays, & Fridays, & as always I welcome your comments & suggestions.
So far, the series has covered:
the definitions of propositions & arguments,
several ambiguity fallacies,
personal ("ad hominem") fallacies,
& several appeals to emotions or abstractions.
In general, this diary features a couple more relevance fallacies as well as a pair of ambiguity fallacies which have not yet been covered. For the specifics, follow me below...
First, confusing a general situation with its individual cases can produce the following relevance fallacies:
Hasty Generalization.
While being able to understand general concepts certainly helps a person make sense of the world of individual objects wherein we live, problems arise when people attempt to jump to general rules from too few examples. Consider the following argument:
I saw 5 diaries about Mitt Romney on the Daily Kos front page.
Therefore Daily Kos is a site about Mitt Romney.
Indeed, if Kos' "Hate-Mail-A-Palooza" is any indication, some conservative visitors to this site seem to
literally believe some version of this! However, even without considering more than the "Front Page" articles — & even more so when considering the many users & groups overall — this community features diaries on many different subjects that may or may not have anything to do with Romney or any of the other Republican candidates for their party's nomination for President. Simply put, a mere sample of a few hours of Daily Kos, especially if such a sample limits itself to one particular section of the site, will fail to give an accurate picture of the community as a whole.
Sweeping Generalization.
Another failure in generalization can occur when someone assumes that a general rule applies to all individual cases, as in this argument:
Most progressive politicians in America belong to the Democratic Party.
Bernie Sanders is progressive.
Therefore Bernie Sanders is a Democrat.
Yet we know that
Senator Sanders is the
independent Senator from Vermont — though he
caucuses with the Democrats.
Also, one of the most destructive types of sweeping generalization for society is stereotyping of people due to (real or alleged) gender or ethnic characteristics.
The following ambiguity fallacies result from confusing wholes with parts:
Composition.
Several of my sources use some version of arguing that taking the bus won't save gas because buses consume more gas than cars — the point being that such an argument ignores the fact that cars far outnumber buses on the road (confusing the collective & distributive features of a class, in other words). For a simpler "part-to-whole" example, one may consider that a novel may be weaker in quality (due to, say, consistency or overall coherence) than its individual chapters.
Division.
This argument has the opposite problem:
A good plumber is hard to find.
Boudreaux is a good plumber.
Therefore Boudreaux is hard to find.
We're not given just how common good plumbers are in the area, but evidently at least someone has the impression that they are
rare on the whole. Meanwhile Boudreaux, for all we know, may be easy to find in the phone book or in public. "Hard to find", in this case, simply indicates a general impression about
plumbers, not about
any particular one (with the result that those individual ones such as Boudreaux are especially
valued). Division, then, erroneously attributes the qualities of a whole to its parts.
Questions? Comments? Suggestions? The floor is open!