First... sorry for assuming this was a quantity argument. But even among cultures where auto theft is frowned upon, cars are sometimes still stolen... and there are those that rationalize the actions of the theives. The existence of one thief and the fact that his theft wasn't front-page news isn't necessarily evidence that society at large isn't opposed to auto theft (or is less opposed than it should be or is on its way towards accepting auto theft as moral).
Your correct response would have been to point out that it's being investigated and, if it were infanticide, they might be arrested for killing a baby. That shows that the official legal position still frowns on infanticide.
My "correct" response? Correct how? In my mind the official legal position is secondary to society's position. (In India the official legal position still frowns on infanticide but it's still a problem, right?)
I've already given you an example of legal infanticide, as understood by a majority of Americans in polls -- partial-birth abortion. Why isn't it illegal and why aren't people more outraged over it?
Partial-birth abortion is illegal in at least 23 states. As for why it's not against federal law, if I remember correctly the major debate was that it didn't allow for a life-of-the-mother exception. I personally believe the federal law failed because politicians are ill-equiped to argue what makes good medicine. It's likely that state laws failed for similar reasons, though I can't comment on each state specifically.
Personally, I'm glad it failed. I believe every state should ban all abortions (except where the mother's life is in danger -- then it's a sad case of self-defense) but I don't think it should be against federal law. I just don't see which of the enumerated powers should be interpreted to allow the federal government authority to pass such a law. A lot of people ARE outraged. As for why more people aren't -- everyone picks his battles. It simply takes too much energy to be outraged at everything evil.
First, most persuasive discussions between people either on the Internet or in person don't follow formal rules of logic and proof. All I need to do is make a case that the person I'm talking to finds persuasive.
You stated that you could make a slippery slope argument sound by showing that you can't stand still. "Can't"... that was your term. I agreed with you (why? because there is one issue in particular where I find the slippery slope argument persuasive and actually use it... but that's only because I have read the study that suggests a -causal link- between the first step and the bottom of the slope). If you could show that one "can't" stand still then your argument would be persuasive. But to prove "can't" you have to follow formal rules of logic and proof (though I left the possibility of going from "can't" to "unlikely to" with a few of my questions). You've done neither. Perhaps there is another way to make the slippery slope argument persuasive. I haven't seen it.
The problem with these debates is that there is no firm place to stand in the middle and the only two stable places are at the end, too far apart to allow for a gentle sway between the two.
What about you can only kill an embryo if it was going to die anyways? That's where most pro-lifers put the line... every single one of these embryos, through accident or design, is going to thaw and die without ever getting a chance to be born... regardless of whether they'll be used for research or not.
Despite how logically questionable slippery slope arguments are, in the real world, they change minds all the time.
I've seen it used but I've never seen it work. I suspect it happens more often than never but less often than "all the time"... But how often it happens isn't really the issue so much as "is there a better way?" I think there is.
FR is a great community, but in many respects is little more than an echo chamber. I see them batted around on, for example, abortion threads where everyone agrees that they're persuasive (I believe because they all already agreed that abortion is wrong before the thread was posted)... but on subjects where FReepers tend to disagree (for example on Schiavo and crevo threads) they're quickly dismissed by the opponents.
Often, they're dismissed by pointing out how bad things would be if we slipped the OTHER way... a quality which makes slippery slope arguments uniquely vulnerable.
Some FReeper will exclaim "If we start teaching ID pretty soon we'll have to teach flat-earth theory!" which is quickly followed by something along the lines of "Darwinism caused eugenics... if 'evilutionists' are left unchecked what will it cause next?"
Now... the fact that I've never seen a slippery slope argument work might just be evidence that I'm looking in the wrong places. But I still think there's a better way.
The problem with that argument is that it's not "unnecessary".
Geez... talk about arguing just to argue. The loss of life is unnecessary because the research is unnecessary.
It's not an equivalent issue in the case of stem-cell research because you can always ask Grandma. And, at the point where Grandma is so brain dead that she can't be asked and has no chance of recovery, well, we do allow her to be cut up for her organs.
In my example, Grandma was in a coma but not brain dead. Granted it's still not perfect. As you said, no analogy is. Always looking for better ones. In your 'missing organs' analogy do you change the date of the execution to match up with a patient's surgery? 'Cause if not, I wouldnt have a problem with it (how many deaths actually are just?).
An important thing to remember is that convincing the other person that you are right and they are wrong isn't the most important part of an Internet debate. Convincing the lurkers that you are sane and your opponent is crazy is the objective.
I'm neither trying to convince you that I'm right nor am I trying convince anyone lurking that you're crazy. Neither of those goals seems worth fighting for... especially not on a forum like FR. My purpose here is similar to why military forces use wargaming. We're on the same side of this debate, but exploring the weaknesses in each other's arguments here in the company of friends is a great way to prepare for debates that occur 'out there'.
If indeed a slippery slope argument IS the most effective way to change hearts and minds then I want to learn WHY it's so effective (and in particular why it's more effective than what I use) and how we can take advantage of that. If it's not... what other persuasive arguments can be used and what are the weaknesses of those? In that way I guess you could say I am arguing (here) just to argue (out there).