Vagueness, slippery slopes and drawing a line

On April 10th (my birthday week, so we did this at the Red Brick cafe), we covered vagueness, ambiguity and fake precision, along with slippery slopes, domino effects and drawing a line. Vagueness is an inappropriate lack of precision – the arguer does not specify, er, specifics, so that their meaning is not 100% clear. This may be accidental (as in bad undergraduate exam answers), or deliberate: a ploy involving economy with the truth. We were warned that vagueness should not be confused with ambiguity, and yet one of the three forms of ambiguity (yes, there are three forms!) seems pretty vague to me. Ambiguity can be lexical (when one word has two meanings; who doesn’t love a good sultana joke for example?); syntactical (basically the result of bad grammar, e.g. does “a small fish packing factory” mean a small factory, or one that packs small fish?); or referential – the vague (yes, really) use of “his”, “hers” or “its” so that it’s hard to tell who the referent is (e.g. “the woman’s cat bit her toe”). In contrast to vagueness is fake precision; and I can tell you that 79.67843% of philosophers really hate this!! (Actually most of us wouldn’t fall for fake precision, since we are so used to not believing figures ’til we see the N and confidence intervals or similar).

The other cluster of topics essentially consider what happens when there is continuous range of options or possibilities, and one part of that range has some property of interest (e.g. acceptability, legality, safety). “Semantic” slippery slopes are when the arguer slides from one part of the range to the next, implying that they are all the same (thus black is white, because there are shades of grey between them). “Causal” slippery slopes are like domino effects or “thin end of the wedge” arguments: here the arguer implies that one small movement across the range of possibilities will cause much bigger, uncontrollable effects (e.g. smoking dope is the first step towards heroin addiction; recommending larger cages means next thing we know, all animals must have their own landscaped parks, etc). This is a rhetorical device – the arguer is using a loaded analogy involving effects of force (gravity) which as a rule are quite inappropriate:  a spectrum is not necessarily a slope, let alone a greasy one, and if we have good reasons we can always draw a line across it (we do that all the time, and even where those lines are somewhat arbitrary, or drawn in pencil not pen, they are useful and defensible [as long as they don’t involve special pleading!]).