”Would you agree that some programming languages are better than others? If so then one of them must be the best.”
False. A partial ordering doesn’t guarantee a maximum element!
False. A partial ordering doesn’t guarantee a maximum element!
So Lisp is better than itself.
If the extension improves something without making anything else worse under the chosen criteria, that's a Pareto improvement. Otherwise, it's a tradeoff.
https://en.wikipedia.org/wiki/Pareto_efficiency#Pareto_order