The real problem with slippery slope arguments…
… is that people who use them always assume things are fluid in one particular direction and static in all others.
For example: Someone who argues that legalizing SSM could be a slippery slope that leads to bigamy and bestiality never bothers to consider that refusing to legalizing SSM could be a slipper slope to laws forbidding interracial marriage. (Or vice versa.)
All slippery slope arguments are ultimately made with the assumption that the person making them’s opinion is the zenith of virtue and that anything that deviates from it is therefore necessarily “downhill” — which is another way of saying that slippery slope arguments are usually made from a place where self-awareness has taken a temporary bathroom break. Every single opinion we have about public policy — every. single. one. — is just a flag we’ve planted somewhere on some spectrum that flows onward from that flag in both directions.
(I have been meaning to write this for a while, and the threads on my post Kansas made me decide now is as good a time as any.)