It's only a fallacy when there is not evidence given that each step leads to the next. A slippery slope argument is perfectly valid when evidence is provided.The fallacy is in the implicit and unexamined assumption that a must lead to b.

E.g

Taking heroin once is obviously a slippery slope to becoming a heroin addict because taking it once causes you to crave taking it again.

[–] [email protected] 1 points 23 hours ago* (last edited 23 hours ago)

100% agreed. I used the graphic to illustrate the point but really should have just linked to the Wikipedia article, which explains the difference.

In the instance I replied to, the slippery slope is invoked but the steps are not described, and no evidence is provided.

Besides, I'd argue (in good company) that centrism is and has been a cloak for fascism.