Monday, December 21, 2015

Sliding Down the Slippery Slope

In the 90’s, nobody was arguing for smoking bans across college campuses. Nobody was publicly, anyway. The net gains and justifications for banning smoking from family restaurants was pretty strong. Kids who don’t have any choice about where to eat dinner would be going to these places, and inhaling second hand smoke. People who don’t smoke had severely limited options without being in closed rooms filled with smoke. Some pretty significant stuff. And could be viewed as completely different from bars (no kids), smoking lounges (a small subset of establishments), and public parks (outdoors). So there’s no continuum. There’s no slippery slope. These are fallacious.

And yet, here we are.
Ain'y no slippery slope here
The Slippery Slope Argument is often called the Slippery Slope Fallacy, usually by those favorably disposed toward the bottom of the slope and anxious to get there as quickly as possible with a minimum of tumbling and bruising along the way. But it is really neither a fallacy nor an argument.

On the One Hand

History is replete with examples of "give 'em an inch and they'll take a mile." The pre-war course of Hitler's micro-aggressions provides a nicely Godwinesque illustration of a slippery slope. Give 'em a Saarland, and they'll take a Bohemia. Recall also that Griswold v. Conn. legitimized the sale of contraceptives to married couples only, precisely on the grounds of the privacy of the marriage bond, and the thought that this might lead to unmarried couples using contraceptives was dismissed as slippery slopitude. Ho-ho, that will never happen! Likewise the forecast was poo-poohed that such availability would eventually weaken the whole concept of marriage and turn women into sex objects. And yet, here we are. So too the late Daniel Pat Moynihan's "defining deviancy down."¹

Hence, as Will Truman contends in "It’s 1987, And That’s a Slippery Slope Fallacy," a slippery slope is not ipso facto fallacious.
1. Defining deviancy down.
"[O]ver the past generation, ...the amount of deviant behavior in American society has increased beyond the levels the community can "afford to recognize" and that, accordingly, we have been re-defining deviancy so as to exempt much conduct previously stigmatized, and also quietly raising the "normal" level in categories where behavior is now abnormal by any earlier standard"

-- "Defining Deviancy Down," The American Scholar, Vol. 62, No. 1 (Winter 1993), pp. 17-30

On the Other Hand

But neither is it much of an argument, as Tod Kelly responds in "The Slippery Slope of the Slippery Slope." He gives several reasons why SS's are poor arguments:
  1. They are largely dishonest and lazy attempts to “magic” away strong arguments against one’s position.|
    For example, "instead of rebutting the arguments in favor of same-sex marriage (Kelly writes), it is much easier to claim that it will lead to 'a world where people marry turtles.'"
    TOF: Maybe not turtles, but perhaps a Ferris-wheel, a roller coaster, the Eiffel Tower, a warehouse, a Laborador retriever, a pet goat, one's self, and minors.

  2. They are not really tools for convincing people who disagree with you that you’re correct; they’re simply a way to preach to your own choir — while potentially shrinking it.
    That legalized medical marijuana may open the door to legalized recreational marijuana may seem a very strong argument against it -- if you already believe smoking pot is wrong. But to those who believe medical use and recreational use are separate issues, it is not. (And if you believe blowing weed is good, then it's an inducement!)
  3. They assume a wholly static world where one does not exist.
    Slippery slope arguments are really pleas that we do nothing new because bad things might happen.
  4. They are entirely indiscriminate.
    "There is literally no position," writes Kelly, "no matter how innocuous or righteous, that a SSA can’t 'prove' will lead to the end of civilization as we know it."
    • Legalize marijuana today, and eventually you’ll legalize crack cocaine and heroin. But...
    • Refuse to legalize marijuana, and eventually you’ll use the exact same reasons to criminalize alcohol and cough medicine
Being a former quality engineer, TOF finds #3 and #4 to be features, not bugs. As we observed recently, it is a form of confirmation bias to deny slippery slopes tout court. One should always, for any proposal deviating from the status quo, consider what might go wrong, from either a botched implementation or a wholly successful one. Remember: most mutations kill the organism; most experiments end in failure. We call such considerings Failure Modes and Effects Analysis or SWOT analysis. (More on these later.) Change anything and it will get worse! Depend on it. No good deed goes unpunished. The only real question is whether the bad results of the change will be less bad than the bad results of continuing as-is.

On the Gripping Hand

Brandon Watson takes a third point of view (as does TOF). The responses to the Slippery Slope are as bad as many slippery slopes arguments. But the Slippery Slope is neither an argument nor a fallacy, but rather a challenge. Their purpose is to raise the question of whether a position is properly thought out in the first place.

Brandon distinguishes three different slopes:
(A) Causal extrapolations: These are what the phrase 'slippery slope' often seems to suggests to people's minds. This kind of argument is basically a causal prediction; 'if you keep doing this, you're heading to such-and-such bad consequence'.
[For example: that due to federally guaranteed student loans, the price of universities will rise to absorb the funds available, saddling a generation of students with a lifetime of crushing debts.]
(B) Motivational extrapolations: These are the camel's nose or thin-end-of-the-wedge arguments. They could all be summarized by the saying, 'If you give them an inch, they'll take an ell'. [T]hese are estimations of political strategy, not tendencies to effects. 
[For example, an argument against same-sex marriage might be predicated not on whether gay marriages will somehow entail women marrying inanimate objects, but that some of those pushing the boundaries are likely to keep pushing those boundaries. Or that many of those advocating medical marijuana are opposed to all drug laws and fully intend to see them all repealed.]
It is instructional to compare these two extrapolations to Moynihan's "altruistic" and "opportunistic" reasons for redefining deviancies. Moynihan gave as an example of altruistic redefinition the emptying out of the mental hospitals following the Community Mental Health Centers Construction Act of 1963, Kennedy's last public bill-signing. The supply of mental patients was overwhelming the number of beds [and trained caretakers] available in asylums. Just as the number of miscreants in Puritan New England always seemed equal to the number of stocks and whipping posts, the number of mental hospital beds limited the number of mentally ill that society could "afford to recognize." The asylums were closed, but the community mental health centers -- imagined as places where the ill could be drugged -- were never built. (The money vanished into block grants and was used for other purposes. Crazy people don't vote.¹) So the consequence -- a burgeoning "homeless" problem, to be addressed by "affordable housing" -- was a causal extrapolation of the well-intentioned act.

In Moynihan's opportunistic redefinition, a growth in deviancy makes possible a transfer of resources, including prestige, to those who control the deviant population. This control would be jeopardized if any serious effort were made to reduce the deviancy in question. This leads to assorted strategies for re-defining the behavior in question as not all that deviant, really. His example is the breakdown of the family consequent to no-fault divorce and the concomitant epidemic of single-motherhood, fatherless boys, and street crime (not to mention mass shootings, which blossomed in the 70s and 80s). But this opened up opportunities for sundry groups to champion (or bewail!) the situation, provided nothing substantive was ever actually done.
Brandon's third category of slippery slopes is different in kind: 
(C) Identifications of justificatory imprecision: These are about principles or precedents and conclusions that can be drawn given them; given such-and-such principle or precedent, there doesn't seem to be anything that prevents one from also concluding that such-and-such bad thing is good for the same reason.
[For example: If same-sex marriages are justified because... Consenting Adults! What prevents the same Consenting Adults argument from being used to justify polygamy or brother-sister marriage, et al.? It's not that gay marriage leads to the latter in a causal sense; nor even in a motivational sense (advocates of gay marriage are not by and large keen on incest). The issue identified here is that the justification to support X can be just as easily used to support Y. ]

A similar slippery slope was used against the Patriot Act. If we use this law to pursue terrorists, why cannot They use it to pursue drug lords, tax evaders, or Ma and Pa Kettle?
1. Crazy people don't vote. Or considering the outcomes of sundry elections, perhaps they do.

The Root of the Slippery Slope

Glass bottles made on an I/S machine
The root of the slippery slope lies in the number continuum. Consider a quality, such as the weight of a glass bottle made on an Individual Section (I/S) machine. The weight of the bottle is essentially determined by the cut off shears in the gobber. This snips of a gob of molten glass extruded from the furnace and drops it into the first mold. In multiple-mold sections, a needle splits the gob into two or three individual gobs. The one in the picture appears to be two molds per section.

Now, if the bottle are made at too high a weight, we will use more glass per bottle, which raises the material costs and the shipping costs. Therefore, you want to make the bottle as light as possible. Costs go up as weight goes up.

However, if the bottle is made too light, it becomes too fragile to endure the slings and arrows of outrageous fortune, leading to breakage. In the case of pressure ware (such as soda or beer bottles) the lighter bottle may under certain circumstances explode. This raises the possibility of lawsuits.¹ Costs go up as weight goes down, too. Just a different set of costs, is all.

Hence, you are caught between the proverbial rock and hard place. You want to make the bottle light without making it too light. You want to make it sturdy without making it too heavy. Adding the two cost curves together, give you a total cost curve, which looks like (but may not actually be) a parabola. Somewhere within the range, this parabola will have a minimum and this is your minimum cost point. Any deviation from this ideal weight in either direction will increase your costs.

Which is tough cases all around, because no machine or person will ever execute task exactly the same each time. There will always be variation due to a host of causes too fine and numerous to be worth identifying.² The good news is that (except in some circumstances) a little bit of variation only increases costs a little bit, and so it can be tolerated as a practical matter. The limits on the variation that can be tolerated are called (wait for it) the tolerance limits. You can draw two vertical lines on either side of the minimum cost point. Items inside the tolerance limits are acceptable, those outside are the work of Satan, expelled to the outer darkness, where there is wailing and gnashing of teeth.
1. may under certain circumstances explode. For example: If you were to put a case of beer in your car's truck, park it in the hot Arizona sun all day, then at the motel that evening, pull some bottles out and shove them into a bucket of ice to cool them down. This is known as Thermal Stress.
2. too numerous to identify. Hence, we call the resulting variation "random," which means "we don't know the actual cause."

The Fatal Flaw

The fatal flaw in the tolerance concept can be seen by considering three bottles: A, B, and C. A is smack dab on target, B is just inside the tolerance limit. C is just outside. The rules tell us that we must treat A and B as if they were the same -- they are both "in spec" -- but everyone, including great-aunt Matilda, knows that B and C are more like each other in terms of cost and functionality than either one is like A. Therefore, C is referred to the Material Review Board, which is an official body formed to say "We didn't really mean it when we issued the specs." So C is shipped "on deviation." No one seems to notice or complain.

Sooner, rather than later, along comes D, which is a little bit further out of spec. If you accepted C, why not D, which is only a little heavier? Eventually, the tolerance limits are made of rubber bands, to be stretched as needed to accommodate that which was naturally produced, until finally some real clinkers get through, the customers complain, and the limits are made tighter than they were in the first place.

Measurements above the upper tolerance limit have been
recorded as being [just barely] inside just to avoid the hassle.
An alternative strategy is to relabel what was once out of bounds as if it was in bounds; as in the example shown to the right, where measurements out of spec have been recorded as in spec. SInce when people lie, they try to minimize the amount of lie, they fudge the data so that it is just inside the spec limit.

And that, mi amigos is the slippery slope. We draw a line in society and say "Beyond this lies deviancy," but then we encounter things that are only a little bit deviant and we remember that deviations also occur normally. We can either tighten the limits and anathematize things once considered OK. But that might include us, so we redraw the lines to tolerate the petty deviations and, eventually, come to regard these as "normal."

Currently, we are building prisons as fast as we used to build asylums -- and for many of the same people -- and yet they are stuffed to the gills. We are reaching the point where society literally cannot afford to regard many of those inmates as sufficiently deviant to occupy valuable prison space; so... victimless crimes,... non-violent offenders,... early release,...  Jack Abbott,... Willie Horton...

There is no such thing as a good deed... And no such thing as an evil deed. There are good impulses, there are evil impulses, and that is all. Half of the results of a good intention are evil; half the results of an evil intention are good. No man can command the results, not allot them.


So the proper course of any proposal is to thoroughly vet the foreseeable outcomes. What might be
  • the long term results, and not merely the short-term; 
  • the unintended consequences and not merely the intended; 
  • the side effects and not merely the main effect. 
You can rid your dog of fleas by setting him on fire. Fleas cannot survive elevated temperatures. Neither can dogs, of course, but by gum! you get rid of the fleas! By barring Italian immigrants to the US, you can keep out the Lucky Lucianos. But you also keep out the Enrico Fermis.

Failure Modes and Effects Analysis (FMEA) is a systematic examination of a plan or design, component by component, in which we ask
  • How can this component fail? (Failure Mode)
  • What can cause this failure mode? (Cause)
  • What are the effects of the failure if it does happen? (Effects)
Then we rate the likelihood of the cause occurring and the severity of the effect. (There are other bells and whistles, but let's stick to basics.)  Using a simple Low-Moderate-High scale, the two dimensions of risk can be balanced against each other. Anything that is HH -- highly likely and highly critical -- is a signal to reconsider the whole idea. 
Slide from Oriel/STAT-A-MATRIX
 However, the overall intent is not simply to vote ideas off the island. It's to identify risks, so the plan may be altered to address the risks. For example, consider the pressure vessel and the risk of explosion.
A variety of mitigation actions have been suggested in order either to reduce the likelihood that an explosion will take place or reduce the severity of the explosion in case it does. When these actions are incorporated into the plan the Risk Matrix can be revisited. But there needs to be some confirmation that the actions were taken. Remember, when JFK closed all the asylums, the act required that neighborhood clinics be set up to keep the quondam inmates from becoming the homeless problem. But for the most part, these clinics were never built! Imagine if a private manufacturer had included a safety net in the design, but then never built it.

There are two flavors of FMEA, design and process. In dFMEA, we ask what could go wrong even if we achieve the design intent. In pFMEA, we ask how we can screw up in implementing the design. This is the difference between specifying too few neighborhood clinics to handle the load versus not building all the clinics that were specified. Between "doing the right thing" and "doing the thing right." This could be as simple (and as catastrophic) as omitting a comma in a do-loop instruction for a space probe. The comma was supposed to be there, but someone missed a keystroke. Bummer. 

Alas, even engineers will often perform FMEA in a perfunctory manner. Faithful Reader can understand that financiers and legislators may be less careful of such "Murphy Engineering" than product and process designers. TOF once assisted some folks in a financial institution to assess failure modes in several proposed new financial instruments and they were blown away. They had never heard of any such a thing.

Then there is the face-off. Describe the current state of affairs and the proposed future state. Then systematically assess the Strengths, Weaknesses, Opportunities, and Threats of both. This is the SWOT matrix. Normally, the Advocates of Change look only at the Strengths of the proposal and the Weaknesses of the status quo; the Opportunities the proposal will open up and the Threats posed by letting the sleeping dogs lie. The conservatives do the opposite. This is the heart of confirmation bias and the disparagement of the slippery slope.
Slide from Oriel/STAT-A-Matrix
Surely it is a radical notion to suggest that Brilliant Ideas actually accomplish the goals they purportedly pursue!


1. (thesis) Truman, Will. "It’s 1987, And That’s a Slippery Slope Fallacy," Hit Coffee, Dec. 1, 2015

2. (antithesis) Kelly, Tod. "The Slippery Slope of the Slippery Slope," Ordinary Times, Dec. 4, 2015

3. (synthesis) Watson, Brandon. "Slippery Slope Arguments," Siris, Dec. 5, 2015


  1. Love the engineering analogy! Or, rather, example.

  2. You know, if you keep thinking in terms of Hegelian dialectic (see References), you're going to end up supporting Obamacare.

  3. You know, if you keep thinking in terms of Hegelian dialectic (see References), you're going to end up supporting Obamacare.

  4. I wasn't aware of the Community Mental Health Act of 1963. My mental health worker friends blame the Reagan administration for releasing the mentally ill onto the streets.

    1. Of course they do. Reagan was the iconic bogeyman. All bad things are to be laid at his feet. But lest we forget JFK's policies were largely indistinguishable from RR's. Today's liberalism is not your grandfather's liberalism.

    2. JFK was arguably a bit to the left of Reagan...but he was almost indistinguishable from George W. Bush (oh profane! he speaks of the unholy!), except Kennedy was a bit to the right of Bush on education (mostly because of No Child Left Behind...which was partly a concession by Bush to JFK's brother).

  5. I agree that the slippery slope is lazy if you use it instead of articulating what's wrong with the proposal itself. If you do articulate it, the slippery slope is redundant. Who cares if abortion causes breast cancer or not if it is first of all the taking of an innocent human life?

    On the other hand, taking assumptions to their logical conclusion is valid. Ferinstance, if two men can marry because marriage is not about procreation and care of children, why not three men? How about two people who are merely roommates and have no particular romantic relationship? Now how about siblings who live together? Ok, do they even have to live together?

  6. Oh, now that you've posted a blog on the Slippery Slope, next thing we know you'll be blogging on post hoc ergo propter hoc. But, seriously, good explanations. I've taught logic classes and it often confuses students when classifying an argument as "slippery slope" or not. This article will help me to explain things better (I hope). Thanks.

  7. This comment has been removed by a blog administrator.

  8. This comment has been removed by a blog administrator.


Wonder and Anticipation, the Likes of Which We Have Never Seen

  Hello family, friends and fans of Michael F. Flynn.   It is with sorrow and regret that I inform you that my father passed away yesterday,...