I realized the other day that I prefer the more general ontological equivalent of duck typing, which I now call duck ontology (I have no idea if theres another name for this; there probably is). If two things look the same, and you can't do anything to distinguish them, then they're the same thing, is how it goes in duck ontology. If it looks like a duck, and it quacks like a duck, then its a duck. Ducks are things that look, act, sound, etc like ducks

The ship of theseus is the same ship as before because they have the same name, they look the same, they are used the same, etc

If you remove small bits of sand from a mound of sand, then at some point you can't do the same things with the mound (eg: load a bunch into a shovel at once), so it isn't the same things as before

This is a very pragmatic model of what things are what. Its probably an example of the category of models that try to use immediate tautologies or their equivalent. Like: the sun is bright because the sun is bright, is a trivial and not helpful tautology. The analogical equivalent of that in duck ontology is like: theseus' ship looks the same to me, simple as

This is probably all stupid and has been fleshed out much better by other people. Works for me