Natalie Hanman, the editor of Comment is free, is launching a new series of long-form articles in which a writer is given space to explore a subject in depth over a longer period, drawing on the expertise of readers and using multimedia to explore particular themes. She asked me to kick it off.

Here goes …

I am in the early stages of thinking about a lecture I am giving in six weeks' time and suggested to Natalie that I would use this space to float one or two themes I want to touch on. Any response will, I hope, feed into (or, indeed, challenge) the shape of the lecture.

In a sentence I want to look at the way the fourth estate has split in three and explore whether this new division – which I, personally, rather like – is sustainable in the teeth of the dramatic economic and technological changes we're experiencing.

What's the three-way split?

There is the press, mostly still privately owned and lightly regulated, which was all we had until the dawn of broadcasting. Then there are public service broadcasters – publicly owned and, in return, pretty stringently regulated in terms of content, balance, impartiality and so on. Finally, there is the new public sphere opened up by digital technologies. (I need a catchier term for this. "Social media" I find a bit deadening.) Without getting into the debates about net neutrality, one might say that no one (yet?) "owns" or regulates this new third division of the fourth estate.

These, as I begin to think about the lecture, are my initial questions.

There are too many of them, so I'd be interested in what others think the really crucial issues are.

1. The press

The issues here seem to me mainly about convergence, plurality and regulation.

In the past, it was a given that public policy ought to ensure that no one individual or company ought to have a dominant share of one medium, let alone two. That held in the national press: no proprietor could be allowed too many papers and would never be allowed simultaneously to own a TV station. This was also true locally: it was thought undesirable for the local newspaper also to own the local radio or TV station.

Is that all for the birds now?

Two immediate pressure points will sharpen this question in the UK:

a) As the economics of the local press become more challenging, there will be a persuasive argument that the future of local news may lie in converged multimedia operations. Owners will make the case that consolidation is necessary. Is that inevitable? Or even desirable? Or should something like the "old rules" still apply, even in the face of the economic and technological forces that are eroding the local press at an alarming rate.

b) If News Corp succeeds in buying 100% of Sky, Rupert Murdoch will end up owning nearly 40% of the national press as well as a TV company that is twice the size of the BBC in terms of funding/revenue. It was previously never imaginable that any one individual would have that kind of dominance over the media landscape. Is this inevitable? Are those who worry about such things fretting unnecessarily? What difference does the extra 60% of ownership make now – or, conceivably, in the future?

Murdoch told a House of Lords inquiry that concerns about ownership levels of the media are "10 years out of date". Is he right? Or is Claire Enders, the respected media analyst, right in her argument that the Murdoch bid for full control of Sky should be blocked on grounds of plurality?

What's the level of market dominance that should trigger plurality concerns? No one's protested very much over Richard Desmond's takeover of Channel Five. Is that because the Express and Five are relative minnows? What if the Guardian or Independent were to merge with Channel 4 News? Or Associated or Trinity Mirror with ITV News? Ie, is it the sheer size and dominance of the converged company that causes alarm? Or are we talking about a principle of separation of ownership between print and broadcast media?

2. The BBC

A few thoughts, which are unrelated to questions about how the BBC is currently run and whether its stars and/or management are overpaid etc.

The first is that the subsidy model of serious general journalism is – with one or two exceptions – the only one that actually works at the moment.

Looking forward into the eye of the digital storm, it's certainly the only one that has any kind of predictability about it. So should we be tinkering with it?

The main grounds for cutting the BBC down in size or scope (it's generally argued, even by BBC supporters) would be if its market impact was provably damaging to others in the news business. Is it? If so, in which areas of operation? Did the BBC's decision not to deepen its regional coverage allow a flourishing of local news from existing players – or, to be fair, is it realistically in prospect?

Or will the opposite prove to be true: that, actually, the BBC could have provided a local service, which the market is currently unable to sustain?

There's no public service broadcaster comparable to the BBC in the US, yet American papers appear to be in as much trouble as UK or European ones.

Irritating though the BBC can be as a competitor, I'm not convinced that we should heap excessive blame on its head, or imagine that financial salvation for others would necessarily follow from taking a chainsaw to the Beeb's cost base. Is that right, or are there examples of the negative impact the BBC has on other journalistic endeavours?

Finally, the BBC represents a broader idea of "public space" that is currently not very fashionable politically. But there seems to be a gulf between public perceptions of the BBC (measured in terms of trust and relatively low levels of agitation over overall value) and the remorseless hammering it gets from its fourth estate cousin, the press.

What's going on here? Is the relentless criticism simply the hostility of rivals? Is it that the BBC has become too large/lost its way? Or is it that the idea of public space itself under threat?

Is there a value in the tension between the regulated/impartial broadcasting model represented by the BBC and the unregulated/partial-as-you-like press?

Is "opinionated TV" inevitable/desirable in this country? How does the public space of the BBC survive convergence – especially in terms of its funding?

3. The digital sphere, aka social media (what's a better name?)

I am thinking of its relationship to the general news environment, as it is being stretched and redefined.

I can think of lots of positive examples where all kinds of valuable and exciting "journalistic" things are happening a) on their own in this space, and b) in combination with conventional journalism. More are always welcome, but I am broadly convinced that this is a new and powerful force in society and in the emerging news ecosystem.

I'd really welcome thoughts/counter-examples on two doubts persistently raised by others.

The first, and most current, is Malcolm Gladwell's argument that social networks such as Twitter are "weak" communities, which are unlikely to be very effective in terms of stimulating real or lasting political change.

The second is the charge that social networks are effective distribution mechanisms and networks, but they contribute little by way of original information. That (so the argument goes) is still overwhelmingly done by conventional news operations. The digital sceptics also argue that social media is an animal with a tiny attention span – ie, it is well-suited to amplifying the new, but not much good at the dogged business of complexity or gradual, patient concentration on an issue. Is that right? What are the best counter-examples?

Finally …

My overarching thought, if that's not putting it too grandly, is that the current balance/tension between the three different manifestations of the old notion of the fourth estate works quite well. It allows for three entirely different ideas of what journalism is, and it's better (with the advent of digital) than what went before, when there was a duopoly between press and TV. But the economic forces that are intrinsic to the digital sphere threaten to weaken the other two spheres – to the point of destroying the idea of plurality they have embodied.

Can regulation of itself help protect this delicate balance – at least until we can understand better where the digital revolution is going? Or are the forces at work here so overwhelming that governments have to step aside and let the digital whirlwind blow through the existing media world and see what's left standing at the end? I've heard Conservative ministers express the latter view.

Who's right?

There are numerous big questions wrapped up in all that – far too many for one lecture. Some people might want to respond on the overall theme of the balance between the three forms of media. Or you might want to tackle one of the three subsections – in which case, it might help if you labelled it at the head of your response.

I look forward to seeing where these thoughts lead …