I’m having a hard time putting into words a very common scenario in debates. So here’s an example:
Issue: Gay Marriage
Side 1: The sanctity of marriage must be protected. Gays must not be allowed to marry.
Side 2: Marriage is already falling apart as an institution. Might as well let gays marry.
Granted that’s not the entirety of the argument (the main thing is the relative morality of gayness), but I hear it a lot. The “might as well” defense. Here’s another example:
Issue: Further development along polluted river
Position 1: The river must be protected. No new development.
Position 2: There are already a lot of worse developments along the river. Might as well build another.
Is “defeatist” the proper term for Position 2? I guess the slope can get slippery where relative measurements enter into it – say if the river is 90% polluted and the new development will add 1% more pollution to it. But as a general principle, isn’t the “it’s already bad, so let it get worse” argument a bad way to go? Am I wrong? I guess it depends on how much of a stake you have in the issue. Personally, I find the sanctity of marriage to be largely irrelevant in contrast to river pollution, but that’s just me.
argument three: marriage is simply a legal contract between two people that leads to the equal ownership of possessions (include children in ‘possessions) accumulated throughout the life (and, in some cases, before the execution) of the contract. and defining who may enter into such contracts is just silly. especially considering tricky little constitution guarantees like equal protection under the law.
Position 1 is a variant of the slippery slope, which may or not be fallacious as used in your examples. Position 2 is just arguing the slippery slope from the opposite direction; that is, we’re already at the bottom of the slope (or nearly so).
As for whether it’s weak to adopt position 2, I think the main problem is that by adopting position 2 you’re more or less conceding the truth of position 1. You could argue your position just as effectively by shrugging.
Note that this is also an example of the sort of argument that is apt to go in circles, because the two parties are arguing about two different things. The person taking position 1 is arguing how things ought to be, whereas the person taking position 2 is arguing about how things are. Obviously, these are not the same.