[AlexTWithBeard]

Many legal things are evaluated lazily: the law may not specify exactly what the vehicle is, but if such need arises, there are tools, like precedents and analogy, to answer this question.

The way to think about it is like a logical evaluation shortcut:

  if not ADA_EXEMPT and IS_VEHICLE:
    DISALLOW_IN_PARK

Since wheelchairs are ADA exempt, a question of whether it's a vehicle will probably never be risen.

Using the IT analogy, it's less like C++, where each statement must pass compiler checks for the application to merely start, but more like a Python, where some illegal stuff may peacefully exist as long as it's never invoked.

EDIT: grammar

[timerol]

None of ADA_EXEMPT, IS_VEHICLE, or DISALLOW_IN_PARK can be easily formally defined. And the mere mention of "wheelchair" adds an additional ADA-related logic exemption. What about bicycles? Strollers? Unicycles? Shopping carts? Skateboards?

And even if IS_VEHICLE was formally defined, that doesn't help, because the concept isn't reusable. It's perfectly normal for "No vehicles allowed in park" and "No vehicles allowed in playground" to have different definitions of what counts as a vehicle, based on what would seem reasonable to a jury

[ogogmad]

I don't know if I've misread some people here, but it's silly to insist that the law be a formal system. It's impossible. Common Law uses judicial precedent to fill in ambiguities as they turn into actual disputes. If you had to formally define everything, then a) it would run into the various Incompleteness Theorems in logic (like Goedel's) and the Principle of Explosion, so it would go hilariously wrong b) No law would ever get passed, as people would spend years trying and failing to recursively define every term.

[gilleain]

Appropriately enough, Gödel had this very problem when getting US citizenship, where he tried to argue that the law had a logical problem:

"On December 5, 1947, Einstein and Morgenstern accompanied Gödel to his U.S. citizenship exam, where they acted as witnesses. Gödel had confided in them that he had discovered an inconsistency in the U.S. Constitution that could allow the U.S. to become a dictatorship; this has since been dubbed Gödel's Loophole. Einstein and Morgenstern were concerned that their friend's unpredictable behavior might jeopardize his application. The judge turned out to be Phillip Forman, who knew Einstein and had administered the oath at Einstein's own citizenship hearing. Everything went smoothly until Forman happened to ask Gödel if he thought a dictatorship like the Nazi regime could happen in the U.S. Gödel then started to explain his discovery to Forman. Forman understood what was going on, cut Gödel off, and moved the hearing on to other questions and a routine conclusion"

https://en.wikipedia.org/wiki/Kurt_G%C3%B6del#Princeton,_Ein...

[rhino369]

>Many legal things are evaluated lazily: the law may not specify exactly what the vehicle is, but if such need arises, there are tools, like precedents and analogy, to answer this question.

That's how common law and precedents work in the US system. Case A from 1924 said cars were vehicles, but bikes weren't. Case B from 1965 said e-bikes weren't vehicles. Case C said motorcycles were vehicles. And then the judge analogizes the facts and find that an electric motorcycle is a vehicle so long as its not a e-bike.

But the administrative law side of things works the opposite. They publish a regulation just saying "e-bikes above a certain weight qualify as vehicles under Law X."