The acquisition of Twitter by entrepreneur and tycoon Elon Musk - for the hefty sum of 44 billion - is bound to have far-reaching consequences for the functioning of the global public sphere. Although Twitter's user base is much smaller than that of other platforms such as Facebook, it is perceived as the primary digital forum for public deliberation, with many influential figures from across the political and ideological spectrum present.

Musk has fervently argued that, although Twitter is in private hands, it functions de facto as a city's place, where people and prominent personalities debate many important public issues, and thus plays a vital public role in a democracy. Thus, Musk has publicly stated that "freedom of speech is the foundation of a functioning democracy" and that he believes that the platform could err in allowing legal content, as well as be slow to act slowly in permanently suspending accounts.

If Mr Musk is serious about making Twitter a platform that people across the spectrum of opinion can use and respect, and is wrong to allow free speechrather than restrict it, his acquisition of the company should result in a significant liberalisation of its content moderation policies. 

As Twitter has increasingly aligned itself with certain contested political positions, it has undermined its own credibility as an open platform for speechand has artificially impoverished the quality and breadth of the public discussion. 

The purchase of Twitter by a fervent free speech advocate provides a unique opportunity to transform this social network. It can be transformed from an ideological, politically and scientifically partisan platform to one where the voices of the left and the right - and all positions in between - can compete on a more or less level playing field.

Under Musk's leadership, Twitter could become a forum where conflicting perspectives can be set against each other, subject to rational scrutiny without fear of being banned or blocked for offending a member of the boardboard.

However, things are not that simple. The quality of our public sphere depends not only on freedom of expression, but also on the moral and scientific quality of Public discourse. A free public sphere is good and desirable, but if it is full of trolls and uncivil harassers it can become morally and politically toxic.

For Musk, the purchase of Twitter also includes the unenviable - but important - task of devising rules and procedures for deciding what content should be restricted and what should be tolerated in this most important part of the global public sphere.

Relaxing content moderation rules would undoubtedly allow intelligent dissenting voices in the political and scientific community to enrich and expand the public discussionand challenge prevailing preconceptions. However, it is also true that to do so would give a wide berth to interventions of leavequality, ill-informed and offensive. It is probably a price worth paying for a free and open platform, but it is still a price. 

It is also difficult to determine when an intervention borders on illegality or violence. For example, is expressing a desire to harm someone or have bad things happen to them an incitement to violence, or is making false and damaging insinuations about their conduct a form of unlawful defamation? Any content moderation policy will be forced to make tough decisions on a regular basis on this subjectof tricky questions.

Freedom of expression is an important good for social progress, but it is not a panacea for the many and varied pathologies of the digital public sphere, including its highly centralised ownership Structures, its tendency to favour sensationalist and emotionally charged interventions; and its generation of ideologically uniform user communities or ideological echo chambers.

If Musk delivers on his promise to make Twitter less subject to censorship and more ideologically open, it will at least be a step in the right direction.