Slippery Slope Arguments in Legal Contexts: Towards Argumentative Patterns

Saliger (2007, p. 342) states that SSAs “[…] belong to the class of practical consequence arguments.” Yet Walton (2015, p. 275) rightly observes that, although an SSA shares obvious characteristics with consequentialist argumentation, this does not explain the reasoning-mechanism leading from the “starting point” to the “end point” (i.e., how the initial state-of-affairs leads to an unacceptable final outcome). Walton (1996, p. 203) also mentions a connection between an SSA and the argumentum ad absurdum, a type of argument he considers to be based on the argument from consequences. Besides a negative form of the argumentum ad absurdum, the SSA also has a positive form if the outcome is desirable rather than catastrophic (Walton et al. 2008, p. 332).

According to pragma-dialectical notation, ‘1’ marks the standpoint (or conclusion), while ‘1.1’, respectively ‘1.1.1’, mark the premises. The letters ‘a’ and ‘b’ identify a coordinative argument, whose premises are both necessary and, when taken together, can be sufficient for the standpoint; while in multiple arguments (e.g., 1.1, 1.2), the premises can be independently sufficient for the standpoint (Van Eemeren et al. 2002, pp. 69–70).

As Rescher puts it: “([e]ven in reasoning) a chain is no stronger than its weakest link. Non fortiter catena quam anulus debilissimus. This too is true in the rational as in the physical realm. The idea was operative in the principle of Theophrastus in relation to modal syllogisms: Peiorem sequitur semper conclusio partem. The conclusion always follows the weaker part, not only the weaker in point of modality, but also the weaker in quality and quantity” (Rescher 2010, p. 133; capitalization removed).

The available empirical data from the Netherlands only show that both assisted suicide and voluntary euthanasia are relatively uncommon, but there is no support from this data for a direct and inevitable causal relation between both praxes. According to studies from 1990, 1995, and 2001 on medical praxes that shorten life, assisted suicide is “relatively uncommon” in the Netherlands in these years, occurring in between 0.1% and 0.4% of all deaths, whereas voluntary euthanasia occurred in between 1.7 and 2.6% of all deaths (Weyers 2001).

398 U.S., at 60, 90 S.Ct., at 1557, quoting 10 US.C.772(f).

Under the literal rule, a judge must consider what a statute says, rather than what it might mean. The judge will thus assign to the statute a literal meaning (i.e., the ordinary everyday meaning), even if this interpretation results in what might be considered an otherwise unjust or undesirable outcome. The golden rule modifies the literal rule such that, if the literal rule results in an absurd interpretation, then the court should look for an alternative interpretation that avoids the absurdity. The mischief rule allows a judge to exercise yet further discretion, beyond what the literal or the golden rule allows. It requires of the court to consider what the law said before the focal statute was passed, to thus discover the gap, or mischief, that the statute was meant to cover. The court must then interpret the statute in a way that covers this gap. On the purposive approach, finally, the court does not only consider the gap in the old law, but bases the decision also on what the court interprets as the law-giving parliament’s intention (Slapper and Kelly 2011, p. 38).