(from pentemom's comment to this post by Le Sabot Post-Moderne)

Here's a stab: the slippery slope can have the brakes put on at the point where people agree that X does not necessarily imply that X' follows, and where that's a logical position and not merely wishful thinking...

The Pandora's box is when the arguments against going all the way down have been removed by the people by the people who want to take the first step down the slope.