Moving Goal Posts

See FallaciousArgument.

Demanding ever-increasing levels of evidence of your opponent, until your opponent gives up in frustration. You haven't (dis)proved anything, though you may have fooled yourself into thinking you have.

You don't even have to demand increasing levels of evidence; just changing the point that you want "proved" counts as moving the goalposts.

Possibly. Most of the time, in my experience, it has been of the type:

Jack: "Oh, that's not such-and-such... it doesn't do X."
Jill: "Sure it does. Here's evidence."
Jack: "Yeah, but it fails to exhibit Y."
Jill: "Here's an example of it exhibiting Y."
Jack: "Yeah, but..."
The important part is that Jack is making up extra conditions on the fly, rather than setting out the full list of necessary conditions and sticking to them. Arguments about the DefinitionOfIntelligence often degrade into MovingGoalPosts matches.

It is a waste of time and effort to set out a full list of necessary conditions if it can be demonstrated that there exists a necessary condition which is not satisfied. (stringent definition of "necessary")

This would also need a stringent definition of "it can be demonstrated". Typically, when MovingGoalPosts is invoked, the debator merely raises the possibility that some necessary condition hasn't been satisfied and tries to shirk the onus onto the opponent. I suggest two options:

Perhaps 'levels of evidence' is the wrong term. Anyone care to edit the definition to clean it up?

This same problem is faced daily by salespeople, as the customer keeps making up yet another reason or objection to not buy. A sales technique is to turn the question around:

Jack: "I don't want it unless delivery can be on Friday."
Jill: "Delivery can be Friday."
Jack: "Yeah, but will it be giftwrapped"
Jill: "It can be giftwrapped"
Jack: "Yeah, but there is only one widget included"
Jill: (hmmm)
Jill: "If I include another widget, will you buy?"
Jack: "Uhhh..."

At this point Jack either has to say he won't, in which case the question is a deliberate waste of time, or Jack says he will buy, which means he can't offer up another objection.

He could say however "Well, it depends...", at which point Jill can extract all the conditions and objections up front by asking "depends on what?". If Jack balks at listing more objections without getting answers, Jill can always ask the "If [x], will you buy?" question.

Note that perfectly logical arguments can appear to be MovingGoalPosts at first sight.

Jack: "Oh, that's not such-and-such... it doesn't do X."
Jill: "Sure it does. Here's evidence."
Jack: "Yeah, but it fails to exhibit Y", and I can show that Y is a special case of X
Jill: "Here's an example of it exhibiting Y.", or "Gosh, your right, it doesn�t do all X"

An example would be

Jill: "Boiling water sterilises it completely"
Jack: "No, to do that you would have to kill all germs."
Jill: "Sure it does. Pasteur demonstrated that."
Jack: "Yeah, but there are some microbes called thermophiles that can stand boiling water for short periods. "
Jill: "Gosh, that�s true, but boiling is still sufficient to purify water for drinking"

EditText of this page (last edited July 8, 2007) or FindPage with title or text search