Are chains of causation inexorable and dire? Does a continuum between extremes mean that neither extreme differs, or that one of those extremes doesn't exist?
Here, we'll discuss the Slippery Slope, and the two False Continua, similar arguments though representing causal and semantic versions respectively.
But first I'll deal with its causal version, the Fallacy of the Beard, also the Camel’s Nose fallacy. The first name comes from an analogy with the greying of a man's beard, in which the amount of grey is small at first, but inevitably progresses until the entire beard is grey. The second name comes from a fable in which a camel is permitted by its owner to stick its nose in the tent for warmth from the cold desert night air, quickly followed by the entire camel, who crowds its owner out of the tent and into the cold.
The slippery slope asserts that a position or claim is unacceptable because if accepted, its worst extreme must inevitably follow, without sound reasons as to how or why this must be.
It's a fallacy that's both committed and labels itself as an argument strategy at the same time, with the use of such opening phrases as "It's a slippery slope if..." or "It sets a bad precedent when..." and so on.
A superficially similar form of argument can be a strong line of reasoning when the chain of inference is laid out and each link logically follows, but the fallacy refers to the specious usage, as below:
The public teaching of comparative religion leads to awareness of religious diversity, then to religious doubt, then to agnosticism, then to atheism, then to anti-theism, then to nihilism, then to moral degeneracy, then inevitably to the disintegration of a society in total anarchy, so we don’t want comparative religion courses taught in our public schools.
Beside the fact that the evidence just doesn’t bear this ridiculous chain of consequences out, note here that no supporting reasons or other justification are ever provided as to why this chain must be true.
The Vagueness, or False Continuum, is below, used in two ways:
One version attempts to argue that concepts B and E shade into each other along a continuum without any fine dividing line between them, so they are the same thing, that no distinction exists.
But it just doesn’t follow that:
There is no difference between blue light and yellow light, despite no sharp dividing point in wavelengths in the visible spectrum.
Nor does it follow that:
There is no separation between humid or dry weather when the moisture in the air at any one time and place varies in degree from high to low.
The second variant is used to argue that concept B differs so little from concept E with no fine line between them, that concept E simply doesn’t exist. As for this one, it doesn’t follow that:
Truth doesn’t exist because of the continuum between truth and falsehood. The concept of truth is without any objective reference. It's all falsehood, and we don't know a thing!
These two fallacies, causal and semantic, are distinct, but they are mentioned together here as the use of the semantic version can and does often lead to the commission of the causal version. Their joint use implies that a slip from position or claim B to E is inevitable because of the lack of a fine point of separation between them.
The tricky thing about fallacies like these, often used by postmodernists and political buffs with conspiratorial leanings, is that they are common in social discourse, especially in academic settings like the Humanities, and oddly hard to recognize as specious while committing them oneself.
Learn to note them, and picking them out reliably becomes easier with practice, even to avoiding the temptation to use them in your own arguments, which is always a plus.
Tf. Tk. Tts.