[Alex]

Slippery slope arguments aren't necessarily invalid but they're very problematic for reasonable debate since, to a degree they can't be negated. Doing so requires proving a negative.

When it comes to any legislation that reduces in any way access to abortion it is reasonable to be worried about the slippery slope since it is almost always being submitted by people who are quite explicit that the ultimate goal is for abortion to never be legal. Does that mean any such legislation is, on its face, a travesty? I'd say no.

When it comes to health care it is reasonable to worry that the current proposals are the first step on a slippery slope to single payer since many of the people pushing it in the past have said that is there goal and are now counseling that it is best to get there incrementally.

"Even though X isn't that horrible of a thing I oppose it because I see it as the first step towards Y, which is completely unacceptable to me" is not a bad point of contention. Especially if it opens a door for negotiation wherein a proponent of X could include roadblocks that make Y less likely to occur. Or at least attempt to show that the benefits of the intermediate step are sufficient that the battle lines should be drawn at the next step down the slippery slope.

The two problems in how most people using slippery slope arguments are

1. They intentionally misstate (or have been themselves deceived into believing) that the feared end state is actually the immediate result of the item being discussed ("requiring a doctor to mention the opportunities of adoption will result in 2 million botched back-alley abortions a year!" or "the House Ways and Means bill is British style socialist medicine!").

2. Misstatement (intentionally or otherwise) of the intent motivating various parties. I grew up being told not that certain Reagan policies would hurt the poor but that Reagan wanted to starve the poor. This is also an extrapolation of unintended consequences, which are also a type of argument that is nearly impossible to negate. "The mechanism by which the proposed plan funds end of life counseling will create a series of perverse incentives that after several iterations and over time will discourage people from using ever-less-drastic measures for extending life" is a reasonable argument. "Obama wants to euthanise old people" is not. "Requiring parental notification is going to lead to more young girls seeking abortion through less safe means resulting in negative health consequences to both them an the fetus at a rate that negates any avoided abortions" is a reasonable (and by reasonable I don't mean correct, just that it allows for discussion) argument. "You'd rather girls die in back alleys with hangers up their nethers than allow even one safe abortion" is not.