It might strike many as rather more muscular than liberal.
I would have no problem signing up to being somebody "who believes in liberal values and believes that those values must be defended and promoted" (with extra helpings of motherhood and apple pie), though I imagine that those (mostly mythical) moral relativist straw men could easily fall at the first fence. The rest of us might then get on with the real and legitimately contested debates in a liberal society, about precisely what these shared liberal values consist of, and what the best means of protecting and entrenching them successfully are.
If "fundamental human rights" sound like a useful place to start, things might start to get heated. These Muscular Liberals certainly seem very much up for a shouting match over civil liberties with what passes for liberal opinion of a weedily non-muscular sort (David Davis, for example). When it comes to the muscular means, David Cameron and Nick Clegg are among many who would seem to fall short on some of the muscularity tests set out for liberals here.
So the Muscular Liberals are very sceptical of what the Coalition thinks is a 'liberalising' rebalancing and rebranding of security policy, but which they rather fear is going rather soft on terror and security. So there is a robust defence of control orders "from the hysterial attacks of civil libertarians" as nothing less than "a testament to the abiding power of our liberalism".
The Muscular Liberals are concerned too that the Cameron government, by not renewing the 28 day detention powers risk seeing the dangerous squad 'turned loose without a care in the world' after a fortnight in detention. (In fact, the Coalition's reversion to 14 days has been rather over-sold, since it includes preparing legislation to return to 28 days, with Parliamentary approval, if this is needed).
How muscular do you need to be? Muscular liberals are "liberals who have grown a backbone", blogs Wind-Cowie for Demos today, offering an approving analogy with Irving Kristol's description of neo-cons as "‘liberals who have been mugged by reality"
Muscular liberalism is not new - it traces its heritage through Bush and Blair to Theodore Roosevelt and Lord Palmerston - but it has never been more necessary than in our increasingly fractured and dangerous modern world.
Invoking Teddy Roosevelt and Palmerston does rather put the tonal emphasis on being ready to bring a gunboat. (The echo of Muscular Christianity in Cameron's term is surely a deliberate one. And perhaps this comes from that distinctively British combination of my mixed Indian-Irish heritage, but my own understanding is that the British Empire wasn't always entirely liberal in every respect from everybody's point of view. It was, however, dissolved into the Commonwealth with some liberal and conservative grace for the most part, though that "retreat" to progress the cause of fundamental liberal rights was never nearly muscular enough for some).
More seriously for the future argument, what doesn't seem at all clear from this take on 'muscular liberalism' is where or whether it differs from neo-conservatism in any significant respect.
Perhaps it isn't meant to. Wind-Cowie seems to think that George W Bush was very much the man for the moment over the last decade. He is also a great fan of Joseph Lieberman, but believes that electing Al Gore in 2000 would have been "simply wrong for America". So it might be that the Muscular Liberals believe that neo-conservatism has been misunderstood and traduced, and that the central issue is to get back on the horse and pursue the argument that George W Bush understood that this was the only way to keep us safe in the post-9/11 world.
Well, that's a point of view, and one legitimate perspective in the debate, but a much less widely shared one than it was.
But that strategy seems to me unlikely to be an effective one for the "muscular liberals" - and it would certainly be rather too narrow for all but one strand of the current Coalition government, still less British society as a whole.
So, instead, I would argue that an important foundation of any robust and value-based liberal internationalism would be an account of where it differs from neo-conservatism and what it had learnt from the last decade.
This would be particularly important for those who want to rescue and recast ideas of liberal internationalism (which I have argued should be an important project for the internationalist left, as well as right right) and to guard against the danger that support for the values of democracy and human rights themselves are diminished by the experience of the Bush era.
That is also something recognised by the more thoughtful sympathisers with neo-con goals of spreading democracy and human rights, such as Francis Fukuyama in his After the Neo-Cons insider's obituary of the idea, as well as by the many critics of the failures of neo-conservatism from a range of liberal, conservative, social democratic and left perspectives.
Indeed, the experience of Tony Blair is instructive here. Blair's own agenda was considerably broader than that of Washington's neo-conservatives. His 1999 Chicago speech was about liberal intervention and a new multilateral framework ("new rules for the international community", no less, an idea of which neo-cons are deeply sceptical). Blair's 2001 Labour conference speech argued that being tough on terrorism should be underpinned by a rather social democratic agenda for global development.
So Blair was not a neo-con, though he became a hero of that tribe ("a non-neocon raised by neocons to the exalted status that was until now accorded only to Winston Churchill and Margaret Thatcher", as Stelzer himself put it to explain Blair's inclusion in his collection of key neo-con texts). As I have written before, the fatal flaw of Blair's liberal internationalist project may well have been that he never sought to distinguish it from that of the Washington neo-cons, whom he hoped would offer him the power to pursue it. ("I've never known what people mean when they go on about this neocon thing", as he once told Jim Naughtie). Wind-Cowie blogs too that neo-conservatism is "another hard-to-define political movement".
But the term neo-conservative does have a coherent meaning, even if it has also become too widely sprayed around as a term of generic abuse. Fukuyama's useful definition of neo-conservatism is probably the best concise definition which has been offered.
"Firstly, a concern with democracy, human rights and more generally the internal politics of states; secondly, a belief that US power can be used for moral purposes; thirdly, a scepticism about the ability of international law and institutions to solve security problems; and fourthly, a distrust of ambitious social engineering projects."
As I have written before, my view is that a robust liberal internationalism, certainly with a social democratic perspective, would share the first end about the value of extending the reach of democracy and human rights, but would differ significantly from neo-conservative arguments about the means to pursue this.
The Fukuyama definition reminds us that neo-conservatism was a domestic ideological project before it was an international one. For that reason too, it might perhaps capture the worldview of Progressive Conservatives, both at home and abroad rather well. Yet Fukuyama's definition might fit many Big Society 'progressive conservatives' rather well. Some at least share that curious (and defining) neo-con combination of being enormously confident about the ambition of muscular liberalism to spread democracy and human rights around the world, while warning sceptically of the limits of the 'big state' to achieve social change in developed societies.
So this would be my first challenge to try and clarify the new doctrine of 'muscular liberalism'.
So is "muscular liberalism" simply the return of neo-conservatism in a new guise? If not, what are the core differences and disagreements between muscular liberals and neo-conservatives about?
Since that significant ideological agenda which did so much to shape the international politics of the last decade, one of the first questions for the Muscular Liberals is to ask whether the new idea is to offer us all more of the same.