The Gish Gallop is an argument strategy named after Duane Gish, one of the foremost proponents of young earth creationism (YEC).  Props for the name apparently should go to Eugenie Scott of the National Center for Science Education, and if not she surely deserves mad props for plenty of stuff anyways.  The Gish Gallop is a specific example of “quantity over quality,” a concept that anyone who ever wrote a book report with a minimum page requirement can certainly appreciate.  However, just like that last milked page of your Huck Finn report definitely wasn’t a good analysis of Mark Twain’s fine novel, the Gish Gallop isn’t a valid or honest way to argue a position.

The idea behind the Gish Gallop is to throw insurmountable piles of evidence and assertions at your debate opponent.  That way, no matter what, after the debate you can claim that your opponent never addressed most of your claims.  The ‘galloping’ aspect comes into play when your opponents try to pin you down to one specific topic.  When they try that, you throw up a quick smokescreen and then gallop away to something else.  Eventually you’ll either come to something that they aren’t versed in (which you can harp on to make them look terrible), or the debate will run out of time.

An example would be illustrative:

Moderator:  Welcome to the evolution-creationism debate!
Biologist:  Thanks for having me.
Gish Galloper:  Evolution violates thermodynamics.
Bio:  Actually, life forms aren’t closed systems, so their entropy can decrease.
GG:  Tornados don’t make planes.
Bio:  That’s a terrible analogy for evolution-
GG:  If humans evolved from apes, why are there still apes?
Bio:  Well-
GG:  There aren’t any transitional fossils!
GG:  No one has observed kinds evolving into other kinds!
Bio:  Can we get back to the bit about entropy for a minute?
GG:  No, because Darwin caused the Holocaust!
Bio:  What?
GG:  Evolution violates information theory!
GG:  Mutations cannot lead to new genes!
GG:  Evolution can’t explain the origin of life!
Bio:  [Speechless.]
Moderator:  That’s all the time we have.  Thank you for coming.

I’m having some fun here, of course, but hopefully you get the point.  If the galloper is a smooth talker with enough background knowledge to obfuscate briefly on his myriad points, he can flit from vacuous point to vacuous point and never let himself get grilled on any one of them.

This can also happen with evidence.  Tons of shoddy evidence doesn’t add up to a little good evidence, it adds up to a pile of shoddy evidence.  (Which, of course, is still shoddy evidence.)  Let’s pick on UFOlogists with my next example:

UFOlogist:  Dude, Roswell.
Skeptic:  We’ve been over this a million times.
UFO:  Fine, fine.  What about Tunguska?
Skep:  Sure, we’re not certain of exactly what happened there, but I see no reason to invoke aliens to explain it.
UFO:  What about the pyramids?
Skep:  What about them?
UFO:  Stonehenge, then.  No way ancient man built that without help from aliens.
Skep:  Actually, I heard about a retired engineer who got tired of people saying things like that and started building his own Stonehenge singlehandedly with simple machines.
UFO:  Come on, man!  There are dozens of sightings and abductions happening every week!
Skep:  Where is the evidence-
UFO:  Cattle mutilations!  Crop circles!
Skep:  Ugh.
UFO:  I used to be a skeptic, too!  But I saw the light!

Again, I’m being facetious, but the point remains: lots of bad evidence is still just bad evidence.  It’s not as if bad evidence registers a 1 on the science-o-meter while good evidence earns a 10, so that ten pieces of bad evidence equals one piece of good evidence.  Crummy evidence and arguments are just that: crummy.  No amount of slick debating can change the underlying quality (or lack thereof) of the arguments.

What’s a Skeptic to Do?

This is a tough argument style to combat.  But, hey, no one said skepticism was going to be easy.  It’s always going to be much easier to just believe or disbelieve something, rather than evaluating hypotheses and evidence for yourself (or at least understanding a current scientific consensus).  As such, a skeptic is always going to start with that disadvantage when talking to a diehard true believer.

One technique suggested by Steve Novella of the SGU is to ask the person you’re arguing with for their single best piece of evidence.  It’s an anticlimactic way to argue, but it will pin them to their strongest line of evidence and will give you a single topic to research.  Some googling should lead you to sources covering all sides of the topic, and you can come back to the person with your findings.  Again, it’s not the most exciting or effective way to argue with someone, but it’s better than getting trampled by a herd of galloping true believers.