Most freedom of speech debates now start on the false premise that denying someone a platform is censorship. So we must begin with the correct one, which is that freedom of speech is freedom from punishment. If you are not being convicted and penalised by the state for speaking, then you have freedom of speech. If just one channel of speech has been denied to you, you still have freedom of speech. If we start banning those whose views we don’t like, what next? In general, one should be suspicious of “what next?” arguments, because they assume that humans are incapable of behaving in calibrated ways that don’t inevitably lead to some future state of fascism. We could extend the right to platform and rally to all, but what next? Paedophile rallies? That’s obviously absurd, but it highlights the fact that there are limits, and they are broadly dictated by how much certain values are coded within society. The reason free speech proponents are not out there fighting to hear from child abusers or some radical Muslim clerics is because society or the law regulate the more unpalatable or illegal views away before we have to deal with them at Speakers’ Corner. In On Liberty, John Stuart Mill, one of the great defenders of free speech, says a struggle always occurs between the competing demands of authority and liberty. He argues that we cannot have the latter without the former: “All that makes existence valuable to anyone depends on the enforcement of restraints upon the actions of other people. Some rules of conduct, therefore, must be imposed – by law in the first place, and by opinion on many things which are not fit subjects for the operation of law.”
This is the reason why many platform are now try to find technological solutions (automatic detection) to limit or ban hate speech. If the same technology can be used for censorship that is a key question open to debate.