system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is the slippery slope argument not considered a valid argument?

This has always bothered me, because I can think of instance where bad behaviors can definetly lead to worst behaviors. The classic, if you smoke pot you'll use harder drugs, is clearly not true in itself. Weed doesn't cause you to want to do harder drugs, but since weed is illegal in a lot of places, it could expose you to hard drugs and you could become a user. I understand that this is not always the case, but I'd like to better understand why this is considered a fallacy when it could be true sometimes.
gpt
Fundamentally, A argument (legit ones) require proof and logical deduction.

Slippery slopes USUALLY rely on assumption.

While doing weed = illegal = more likely to commit other illegal act seems legit at first glance, IT IS BASING it's legitmacy on 1 single prospect, and then making more assumptions. You simply don't do this. Just like how you don't see a person being late once and conclude he have trouble keeping time and thus is a unreliable person.

A Slippery slope requires multiple stages and multiple assumptions, where A->B and B->C and C->D thus A->D. We know A =/= D, there is 0 correlation or causation but because you look at the flow of thought thinking "huh it has a point" thus you believe in this false statement. This is why fallacy are so powerful, not just because they are wrong, but because they can seem legit.