Legal vs. Illegal

iFrannie

So I’ve been wondering... consider this: If something is legal, then it is not illegal.

Therefore, if it is illegal, then it is not legal (illegal) via the contrapostive.

So we can conclude an act can only be legal or illegal.

Is this considered a valid argument?

MissChanandler

Hmm I don't think so but I'm feeling confused haha. Basically the argument is:

Legal---> Legal
Illegal--->Illegal
Therefore everything falls into one of the camps.

I don't think it's a valid argument form but it's confusing because in our real world things are either legal or illegal and it makes sense. Anybody else have some insight?

eRetaker

Well the key here is that "Legal" and "illegal" are both sufficient conditions for triggering the other's "not" form. However, it is not necessary that an act is legal or illegal, and the argument as presented leaves a little bit of wiggle room for something to be neither legal or illegal. You're essentially committing a reversal flaw if you assume the argument already accounts for all acts as legal or illegal.

Current Argument:
Legal --> not illegal
Illegal --> not legal

Flawed assumption:
not illegal --> legal
not legal --> illegal

We do not know if something is "not legal" means that it is "illegal." In our current world, yes, there is an implied dichotomy but we can't assume that for the LSAT. @MissChanandler @Haglerfran definitely a tricky one here since it plays on our real world assumptions.

Ohnoeshalpme

It can be made valid if you say, All actions are illegal or not illegal. Therefore any act is either legal or else not legal. But it's not really an argument, just a statement of fact.

In LSAT world, they'll probably give you something like - "Jimmy stole a doll but it was not illegal. Since all acts that are not illegal are considered legally acceptable, then.... Jimmy performed a legally acceptable action." It will play on some discrepency between "not illegal" and something like the above "legally acceptable". We can assume that these are the same thing. Just be careful with terms like "legal" and "illegal" as the LSAT likes to equate these kind of terms with morality, justification and fairness (and a number of other things). They will suck you into trap answer choices by playing on implicit biases that you may have toward these kinds of words.