The Blue Tarp of Doom

Years and years ago I went to a weekend youth retreat with some kids from church at the Roman Nose State Park campgrounds.  There was a big hill leading up to the mess hall there, and at one particular point the organizers covered one side of it with a shiny, low-friction tarp.  They then set some water hoses at the top, allowing it to cascade to the bottom end and create a muddy pool, which we kids had hours of fun sliding into.  That was a slippery slope.

Nowadays I don’t do much slip-n-slide, but unfortunately that doesn’t mean I’m done with slippery slopes.  As logical fallacies go, it’s the one I’ve been accused of committing the most often, and always in the context of an argument over homosexual “marriage”.

Here’s what happens.

1) The advocate asserts that the marriage applicants in question are consenting adults (and/or are not hurting anyone, should be free to marry whom they love, only want to have the love they share be publicly recognized, ad nauseum).

2) I respond that their arguments are equally applicable to incest, and ask if they are willing to live consistently with that reasoning.

3) They accuse me of resorting to the slippery slope fallacy, and all my attempts to explain that, no, I’m actually exposing the fallacious nature of their logic fall upon deaf ears.

That said, I’m going to use this space to provide that explanation in full so that, though I expect the deaf will remain deaf until and unless the Lord changes them, others of my persuasion can at least have my comments without me having to yell over the taunting.

The slippery slope fallacy itself is explained this way by one of my favorite fallacy websites, The Fallacy Files:

If A happens, then by a gradual series of small steps through B, C,…, X, Y, eventually Z will happen, too.
Z should not happen.
Therefore, A should not happen, either.

Now, as far as it goes, I agree that this is poor reasoning.  However, as the Fallacy Files points out:

This type of argument is by no means invariably fallacious, but the strength of the argument is inversely proportional to the number of steps between A and Z, and directly proportional to the causal strength of the connections between adjacent steps. If there are many intervening steps, and the causal connections between them are weak, or even unknown, then the resulting argument will be very weak, if not downright fallacious.

As an aside, does that describe the link between gay marriage and, say, polygamy or incest?  Are there tons of intervening steps, with weak or unknown causal connections?

We have to look no further than Utah’s recent reversal of a ban on polygamy for our answer.  The lawsuit that brought about this decision was of the Brown family of Sister Wives fame, whose argument “relied primarily on the 2003 U.S. Supreme Court decision that struck down the Texas law banning sodomy, which was celebrated by gay rights advocates.”

Hmm, yeah, definitely a tenuous connection guys.

But that’s actually a minor point, because – as you will please note – my argument has never hinged on the idea that one thing will lead to another and pretty soon you’ll have 40 years of darkness, earthquakes, volcanoes, dogs and cats living together and mass hysteria.  (We miss you Harold Ramis!)

Actually, my argument is more simple: what’s good for the goose is good for the gander.

See, I don’t know for sure and for certain that creating a category of gay marriage will also end up creating one for incestuous marriage, or bestiality marriage, or any other such thing.  It might.  I’d wager it will.  But I’m not going to base my whole argument on my predictions for a future that might not happen.

Instead, I want to press for consistency.  This person is lobbying for gay marriage on the basis that these folks are consenting adults?  Okay, then why can’t incestuous couples lobby on those grounds?  I’m not saying they will (which would be a step towards a slippery slope argument), I’m saying that, given the premise that consenting adulthood is all that matters, what’s stopping them?  And if we’re willing to accept that premise, how can we oppose them if they do?

This presentation leaves the person with three options.

A) Live with the glaring inconsistency in their thinking – welcome to cognitive dissonance
B) Resolve the inconsistency by granting that incestuous couples too should get brought on the happy marriage bus
C) Resolve the inconsistency by acknowledging that their reasoning is faulty and they have not presented a convincing argument for gay marriage

Of course, this leaves out the fourth option, which is D) take me to task about how I’m making an appeal to the slippery slope fallacy, which I would be remiss not to mention as its the one everyone I’ve spoken with on the opposite side of this issue resorts to.

And this is why, despite my best efforts, we always end up right back in the mud below the blue tarp of doom.