>Charity implies voluntarily providing support, leaving it to the benevolence (or lack thereof) of each individual. In the end, it teaches people that being uncharitable is OK and an acceptable trait, just like being charitable.
Your use of "teaches" here implies that violence/imprisonment or the threat thereof teaches (if no mandatory charity teaches people that being uncharitable is okay, I assume you mean mandatory charity through taxation teaches people to be charitable?). That certainly isn't a given; how do you know whether people have been taught to be charitable by the threat of violence/imprisonment vs they're only paying taxes to avoid being imprisoned? If you beat a child for swearing, has the child learned that swearing is bad, or or has the child just learned to avoid swearing in front of the parent to avoid beating? I'd argue that one thing it definitely teaches is that violence is an acceptable means of making others do what you want, and to me a person who believes this is far more terrible than a person who's just too cheapskate to give charitably. Millions more people have been killed in the past century by people using violence to compel others and people supporting such ideas (e.g. Stalin, Mao, Hitler and their armies, even the politicians who forced people into the army via the draft) than have been killed from neglect (the 20th century war & genocide death toll far outstrips the death toll from starvation).
>Then, since everybody will be using their own money to pay the "help the disabled" tax, it's a good deed to mandate by law that everybody has to fork out.
Is a good deed a good deed if done unwillingly?
>That would be irrelevant if the desired outcome is to effectively help the disabled, rather than to test honesty of people's charity.
If people are free to donate as they choose and none chose to support the disabled, wouldn't that in fact show that society doesn't really care about helping the disabled anyway? In which case what's the justification for a law forcing something that few in society want? Conversely, given so many people do seem to care about the welfare of the disabled, why wouldn't they express this through charity?