Wait, what? Most exchanges and corporations don't even go by a paper certificate, proving my point: shares (and money, for that matter), are defined by a relationship, not a physical instantiation. If you lose a certificate (if they even still issue them), there are still records of how many were issued, and of when they were transfered to you. As long as that history can be reconstructed, you are still given the voting/dividend rights, and if you aren't, it's lawsuit time.

Same thing with contracts: a contract is a relationship. The signed piece of paper is not the contract, but proof that a contract exists.

It's just a case of Procrustean bedding to act like all property (or rights bundles isomorphic thereto) must be physical.

> Most exchanges and corporations don't even go by a paper certificate,

Except the ones that do. You're right; most don't by default, but if you DO have valid paper certificate, it is a bearer instrument. Who owns it, owns it.

Which is to say, that the physical piece of paper is not a defining characteristic of property in stocks (even one case would mean that paper is not inherently part of stock ownership), just as physical stuff is not necessary in many other kinds of property.