In Defense of Slippery Slope: A Critique of a Postmodern Logical "Fallacy"

In examining two separate listings of recognized logical fallacies, I had noted each had declared the concept of the "slippery slope" as a bona fide error in reasoning.  Wondering that I may have missed something in my courses in logic (taken in the 70's and early 80's), I consulted my old textbooks (works by Irwin Copi and Richard Jeffrey).  I could not find references to this as a recognized logical fallacy, and thus wondered about its present inclusion.  The definition of the slippery slope fallacy is given as: Assuming that a relatively small first step will inevitably result in a series of several presumably negative results.  The example given as a classic misuse of the slippery slope:  Legalizing marijuana will inevitably increase the use of more serious drugs as crack and heroin, which will promote the further legalization of these substances as well.

I have studied this issue of the slippery slope as a legitimate fallacy and deem a few matters wanting.  The first point is the matter of believing the true error being that of false cause.  The process of causation is a complex one, and determining if a correct series of events can be surmised from a first cause is central to this issue.  In some instances, a series of cause-effect situations could be determined.  in making valid judgment decisions, we hope to see what would be affected from them.  The other matter is determining the flow of events that have occurred and the tendency of similar results being attained over similar matters.  In a classical ploy of foiled logic, an argument in the 1950's expressed the thought of allowing African-Americans to sit in any portion of the bus having the effect of conceding other considerations as eating in whites-only restaurants, living in any neighborhood, using the same schooling opportunities.  Happily, the intent of sharpening resolve to deny such advancements of human equality were rejected.  But did conceding one issue lead to the concession of others?  Many slippery slopes are worth the time to schuss down.

The novelty of this logical fallacy also has the difficulty of denying the premise of a "domino effect" recognized in other situations.  In the very point of this concept's introduction, the argument that deserting Vietnam would guarantee the conversion of the whole region of South East Asia to Communism had mixed results.  Laos and Cambodia, yes.  Thailand and Malaysia, no.  The sense that such a tipping of small states from democratic forms to Communism was achieved, but not to the fullest level.  Thus, an ability to offer some predictions is possible, and rejecting the appeal of a slippery slope causality demonstrates an unwillingness to ponder the possibilities or offer alternate results.

The idea of the slippery slope can be traced to one verse in the Psalms:

Surely you set them in slippery places.
You throw them down to destruction. (Ps.73: 18)

The sense of this verse is the psalmist's quandary over the apparent successes of the unbeliever, who thwarts the Deity, yet seems to prosper at every opportunity.  After much frustration over the matter, he comes to realize that having one's goals set on accomplishment and acquisition deprives that person from coming to fear God, and on failing to repent, face destruction at the judgment.  It is the very idea that actions have consequences that ought to make one pause over the decisions one effects. This is the intent of the slippery slope argument, and it should be valued.  Or if seen in this light:

If A occurs, then Z, an unpleasant circumstance will occur.
If A is performed on the hope that Z can be averted, A could be permitted.
But if Z occurs, then the original objection to A would be valid.  But then it would be too late.
Can the prospect of averting Z be justified?

The problem is causality, and the importance (or possibility) of determining what may come versus what must come leads to a need to discuss the matter fully.  Thus the slippery slope argument is an invitation to verify our fears of what may come from thoughtless or inconsiderate choices.  The fallacy of false cause would be valid, but only after establishing the probable results.

Let us not condemn the so-called slippery slope as definite logical fallacy, but the need to pause and reflect.