Many good things have already been said, but I want to add one thing.
If you want an coherent framework that allows free speech but no hate speech, look at consequential ethics. As opposed to rule based ethics (free speech absolutionists).
I.e. we want to maximize the amount of common knowledge (flow of information or free speech) because it leads to the best results over time. If we want to maximize the flow of information, we cannot be absolutionists, because that puts us in a local minimum (failing to optimize properly). In other words, we need to restrict certain free speech to achieve maximum effective free speech.
Many good things have already been said, but I want to add one thing.
If you want an coherent framework that allows free speech but no hate speech, look at consequential ethics. As opposed to rule based ethics (free speech absolutionists).
I.e. we want to maximize the amount of common knowledge (flow of information or free speech) because it leads to the best results over time. If we want to maximize the flow of information, we cannot be absolutionists, because that puts us in a local minimum (failing to optimize properly). In other words, we need to restrict certain free speech to achieve maximum effective free speech.