Refusing to do something because it's "the slippery slope" to some worse terrible thing is a logical fallacy. It is perfectly possible to draw the line and say, "here, and no further".

Case in point: Allowing same sex marriages will be the slippery slope to bigamy, polyandry, bestiality, and so forth. What idiot thinks that one necessarily leads to the other, except in their dirty twisted minds?

Parents draw the line all the time with their children. A child asks for a piece of candy, and Mom says, just one and no more. It is not "the slippery slope" to eating the entire dish of candies, and then going on to become, eventually, a drug addict.

If, by "slippery slope" is meant that a conversation will be opened up to consider further expansion of an action ("just one more, Mom, please?") well, then, yes, that conversation is in play.

But further action is not guaranteed, only the discussion of its relative merits. In my faith tradition, one of our seven principles is to affirm and promote the free and responsible search for truth and meaning. Note the words "free" and "responsible". A conversation may come about as a result of one decision, but further decisions must be freely discussed, chosen, and taken responsibly.

The fear mongers love to cite "the slippery slope" as a reason not to do something. But it is only a way of raising peoples' anxieties, not a logical answer to anything.

It is, in fact, a fallacy. Just ask any parent.