As the gilet jaune revolt moves forward and another destructive showdown looks imminent tomorrow in Paris, the government – and the president – have opted for the lesser of two contradictions. The greater: to reduce your national carbon footprint, you set aside progressive fiscal policy and tax rich and poor at the same rate, putting social justice – a grand French aspiration – in parenthesis. That didn't work. The lesser: to reduce your national carbon footprint, you get alongside low earners and help them through a difficult transition, even though the climate jeopardy of clapped-out diesel UVs is absurdly obvious. But that hasn't worked either.

Perhaps President Macron and the prime minister, Edouard Philippe, have grasped that conspicuous pollution lower down the economic ladder isn't as dangerous as invisible contributions to global warming from consumer-led growth across the board: 24/7 internet, deforestation for vegans and carnivores alike, no-tomorrow air travel, farmed shellfish and all the rest. It's even possible that Macron no longer thinks of rural people as despicable smoking mums who lower the aspirational tone at the school gate as they wait to collect their children.

More likely, though, is that the Elysée and the prime minister know they're on the run. Big concessions have been made to the gilets jaunes this week. The projected rise on the fuel tax in January has been dumped. Indeed no fuel tax rises at all are envisaged in the 2019 budget. There is frenetic talk of trying to raise 'purchasing power' for the less advantaged. The minimum wage is set to increase by 3 per cent, but the rise in real terms is closer to 1.8 per cent. Management, we're now told, should consider doling out end-of-year bonuses to their workers (tax-deductible for the company and tax-exempt for staff). Voices in the government and the parliamentary majority have even raised the possibility of reinstating the wealth tax (impôt de solidarité sur la fortune) which Macron scrapped in January and replaced with a new version (impôt sur la fortune immobilière). Macron has explicitly ruled out a return to the old tax, but the murmurings persist.

This a key issue. The idea of scrapping the ISF was to reduce capital flight: very roughly, big equity portfolios are no longer subject to wealth tax, only land, bricks and mortar. Sweden did something similar in 2007 and it appears to have hung on to its cherished social model. Why shouldn't France? Whatever the merits of this idea, the gilets jaunes loathe it, and are now demanding that the ISF be reintroduced. To call the movement a 'fuel protest', as the BBC does, is a huge over-simplification: the protesters have egalitarian pretensions that go far beyond the petrol tank. And for many – as far as we can tell – it's less a matter of rejecting taxes outright (or social charges for small businesses) than a question about who should bear the brunt. Attac, a movement founded in support of Tobin-style taxes on financial transactions, has expressed its support for the gilets jaunes on the grounds that 'social justice' and 'climate justice' should articulate in any grand policy for change. Another big march scheduled for tomorrow – one of several 'climate rallies' as the COP24 round in Poland toils towards its conclusion – looks likely go ahead in Paris. Here, too, climate-change militants are broadly sympathetic to the gilets jaunes. In a handful of provincial French cities the two sets of marchers are wondering if there's a way to link up.

Tomorrow in Paris will be fraught. Moderate gilets jaunes – speaking for a so-called 'gilets jaunes libres' tendency – have warned activists not to take part in an event which is bound to involve violence. But the government's conciliatory offers have been dismissed with such contempt that the movement feels it's on a roll, 'libre' or otherwise. Intransigence is the order of the day: we saw this earlier in the week when a group of gilets jaunes negotiating an audience with the prime minister pulled out after threats against them on social media. Many lycéens are now caught up in a parallel anti-government protest about university selection (among other things). Yesterday in a school north-west of Paris, 150 lycéens were detained by police and forced to kneel with their hands on their heads. This kind of spectacle does the government no favours; nor does talk of calling in the army – an idea slapped down earlier this week, though there will be armoured cars on the streets in Paris tomorrow.

Seven hundred lycéens have been detained to date. Does their agitation in secondary schools, along with vocal solidarity for the gilets jaunes among the climate marchers, mean we're witnessing a 'convergence of struggles'? Not really – or not until the trade unions and the political class can get a foothold in the movement. Besides, it's entirely unclear what to converge on. When you talk to gilets jaunes at a go-slow, hear them on the radio, or see how easily they can close down parts of France if they want to, they appear to have many classic characteristics of earlier French mobilisations. Easy to forget, in the fog of the real, that the big rallying ground is probably Facebook, which is where this movement took off and how it perpetuates itself.

The government, in other words, is facing a crisis on the streets and on social media. The magnitude of the challenge – and we'd have to go back decades to find anything comparable in France – means we're on unfamiliar territory: we shouldn't be deceived by the long Republican tradition of mass turn-outs in public and ostentatious violence into thinking that we've been here before. As the BuzzFeed reporter Ryan Broderick explains, the gilets jaunes have built their movement 'almost entirely on small, decentralised Facebook pages. They co-ordinate via memes and viral videos. Whatever gets shared the most becomes part of their platform.’ Democracy in action! But some of it has to do with algorithm changes that Facebook made in January, privileging 'local' news and discussion on the grounds that they're likely to be better informed, or less disinformational than global third-party gossip. Not long after Zuckerberg announced the algorithm tweak, disparate local 'groupes colère' (or anger groups) in France began to achieve traction on Facebook, railing narcissistically against all kinds of stuff. Unlike Broderick, I'm not sure the groupes colère were precursors of the gilet jaune phenomenon, but the new Facebook arrangement has done the gilets jaunes no harm either.

Chantal Mouffe has reassured the readers of Libération that the gilets jaunes are tending to the left, if they're tending anywhere. But what left is that exactly? After Hollande's dismal presidency and the collapse of the Parti Socaliste, only the Communist Party and La France Insoumise are left standing. What happens in the short term – tomorrow or Christmas – won't tell us whether Mouffe is on the ball or just a wistful left-wing intellectual.

Two vigorous and influential figures in this fight want it to go the other way. As the cars are set ablaze tomorrow in Paris, Marine Le Pen and Steve Bannon will be watching eagerly from Brussels, where they're scheduled to speak against the ‘Marrakech treaty’, a UN-inspired Global Compact for Migration. The document aims to manage human movement, as the driving factors – climate change included – push millions of people away from their countries of origin. The UN compact is non-binding: a member state can sign up to the idea, as France has done, without implementing the recommendations. But for Le Pen – and Bannon's got her back – it’s the last nail in the coffin of national sovereignty. The gilets jaunes are still susceptible to this line of reasoning as they try to resist the tide of globalisation.