The OP is making a moral case, not a case that it's legal to steal as long as it's not someone's vehicle or tools.
>which by definition there is none.
This is not true, if you consider stealing to be theft of property. See my comment below, where it is not illegal to steal in times of necessity. Legally, you are allowed to takes someone else's property to protect life or seriously bodily harm. This is because we recognize a hierarchy of legal rights. If you consider stealing to be whatever the law says is a crime of theft of property, then it's a begs-the-question fallacy.
>Slippery slope?
No. This is quite literally what ethicists do. The point of finding use-cases where a maxim breaks down is to find the limits of an ethical framework and to determine the first principles. E.g., if you say it's illegal to steal, full-stop, and I show you an instance where it is not illegal to take someone's property, it is a demonstration that your first principle is incorrect.
>which by definition there is none.
This is not true, if you consider stealing to be theft of property. See my comment below, where it is not illegal to steal in times of necessity. Legally, you are allowed to takes someone else's property to protect life or seriously bodily harm. This is because we recognize a hierarchy of legal rights. If you consider stealing to be whatever the law says is a crime of theft of property, then it's a begs-the-question fallacy.
>Slippery slope?
No. This is quite literally what ethicists do. The point of finding use-cases where a maxim breaks down is to find the limits of an ethical framework and to determine the first principles. E.g., if you say it's illegal to steal, full-stop, and I show you an instance where it is not illegal to take someone's property, it is a demonstration that your first principle is incorrect.