Slippery Slope Arguments (Part 2)

By Hendrik van der Breggen
The Carillon, April 28, 2011

Non-Fallacious Logical-Legal Slippery Slope Arguments

(See part 1 here.)

A slippery slope argument is an argument that claims a particular action shouldn’t be taken because this action will result in a series of events which will land us in a place that’s bad or disastrous. The slippery slope fallacy occurs when the argument’s alleged links between the individual events in the series lack evidence or are implausible. Sometimes slippery slope arguments are fallacious, sometimes not.

Today I will look at two non-fallacious, logical-legal slippery slope arguments.

First, I will set out a fun fictional example having to do with the college at which I work. Then I will set out a serious, possibly non-fictional example having to do with a moral issue in contemporary Canadian politics.

1. Fun fictional example.

Let’s say that I approach my college president and propose that our college should give philosophy students the right to free tuition if they choose to accept it. My reason: philosophy students are people who must think very hard and aren’t guaranteed jobs after graduation.

There would be a slippery slope effect here of a logical-legal sort, for sure!

Once the rest of the student body heard about this proposal, students would appeal to a principle of fairness (and would be motivated by greed perhaps) and would argue that all students should receive free tuition, not just philosophy students. Why? Because all students must think very hard and none are guaranteed jobs.

In other words, if thinking hard and having no guarantee of a job after graduation are sufficient grounds for a student to receive free tuition, then whether a student is taking anthropology, business, history, philosophy, psychology—or whatever—doesn’t make a relevant difference. The principle of fairness is fundamental, and the differences between academic disciplines, though real, are incidental. Fairness demands consistency.

Thus, if my college gives philosophy students free tuition on the basis of hard thinking and lack of a job guarantee, then, in the name of fairness and consistency, the college should ensure that all students receive free tuition.

If my boss doesn’t want to be unfair or inconsistent (and doesn’t want our college to go broke), then he shouldn’t give philosophy students the proposed deal.

Our lesson: The above non-fallacious, logical-legal slippery slope argument ensues because the reason behind my proposal justifies much more than intended.

2. Serious possibly non-fictional example.

Now, let’s say a Canadian politician argues that we should give terminally ill patients the legal right to physician-assisted suicide (PAS). Why? Because, our politician argues, we should respect the personal autonomy of those who suffer—i.e., we should grant those who suffer the freedom to choose PAS.

Also, our politician argues, there is no need to worry about the spread of PAS to other contexts, because we can set up legal safeguards so only the terminally ill will have the right to PAS.

With all due respect to our politician, however, we should notice that here too is a danger of a non-fallacious logical-legal slippery slope.

Law courts will do what law courts do: promote consistency. Couple this fact with the fact that the fundamental principle to which our politician appeals is the principle that the sufferer has the right to choose PAS.

From these facts, it’s easy to imagine a lawyer arguing that the choice of the person who suffers is fundamental—most important—and so the importance of the context of terminal illness is secondary.

Surely, or so the lawyer’s argument would go, if someone is suffering from something other than a terminal illness, say, chronic back pain, then that person should also have the right to PAS.

In addition, or so another lawyer’s argument would go, the disabled person who suffers from depression should also have the right to PAS.

And so on.

After all, as the lawyers would argue, the right of the sufferers to choose to end their suffering is a fundamental principle, and the differences between the contexts of terminal illness, chronic back pain, and depression, though real, are merely incidental. It would only be fair and consistent to apply this fundamental principle to all who suffer. Thus, the lawyers would argue, all sufferers should have the freedom to choose PAS.

In other words, if we accept the principle of the autonomy of the sufferer as a justification for PAS, then a non-fallacious logical-legal slippery slope is a reasonable foreseeable outcome.

Hence, if we are concerned about the spread of PAS beyond the context of terminal illness, the politician’s argument should be rejected.

Our lesson: The politician’s appeal to the principle of the autonomy of the sufferer, i.e., the principle that the sufferer has the right to choose physician-assisted suicide, justifies much more than initially intended.

The logical-legal slippery slope—when not fallacious—can be dangerous.


[P.S. Here is yet another example of a non-fallacious logical-legal slippery slope, which is also serious and possibly non-fictional.

Let’s say that our politician argues that we should justify the legal and moral status of same-sex sexual relationships solely on the basis of love. Why? Because, our politician argues, love is a fundamental principle and so love is sufficient grounds for justifying one’s choice of a sexual partner. The personal autonomy that lies at the heart of love is what’s most important—and trumps all.

Should we accept this argument? As politically incorrect and insensitive as this may seem, I think we should not. Why? Because we have yet another non-fallacious logical-legal slippery slope lurking here. The politician’s appeal to love justifies much more than initially intended.

Think about it. If my choice to love X is sufficient grounds for having sex with X, then, yes, X could be an adult of the same sex. But we should keep in mind that X is a place-holder: X could also be, say, a group of people (think polygamy), or X could be a child (think pedophilia).

But, our politician would argue, we could establish legal safeguards to limit X to one adult only. Yes, we could try. I strongly suspect, however, that such safeguards could be overridden by appeals to personal autonomy. If I’ve already accepted love as a fundamental principle—i.e., if I’ve already accepted the personal autonomy to choose to love in whichever way I please as a fundamental right—then, in the name of love, I should have the choice to engage in sex with whomever I want.

I know that this last possibly non-fictional, logical-legal slippery slope argument may seem silly and far-fetched, but I think that lawyers hired by proponents of having multiple wives (e.g., some Muslim and Mormon groups) or lawyers hired by NAMBLA (i.e., the North American Man-Boy Love Association) would disagree.]

(Hendrik van der Breggen, PhD, is assistant professor of philosophy at Providence College, Canada.The views in this column do not always reflect the views of Providence. )

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