From the end of the miners’ strike to the collapse of Lehman Brothers, the left in Britain stumbled from one nadir to the next. How they made a clean sweep of Labour’s NEC elections is a process even the participants do not yet fully understand. However, one thing is certain: this was not a theory-led revolution. The ideas of the modern left were primarily born out of a new kind of practice and some undeniable facts. Neoliberalism had failed. In the survival strategies adopted by governments it has become, as the economist William Davies writes, “literally unjustified”. Davies’ book The Limits of Neoliberalism sums up the wider thinking of the UK left about the system it is trying to replace. It identifies the coercive imposition of competition by a centralised state as the core problem, and contains the most succinct definition of neoliberalism in the English language: “the disenchantment of politics by economics”.

The 2011 protest movements massively strengthened the hold of horizontalist activism. The most influential book here is the 2009 manifesto The Coming Insurrection, by the French anarchist Invisible Committee. Its key message – that the proletariat was over, that the networked human being was the agent of change – resonated strongly with the students who occupied English universities in 2010. Just like the Communist Manifesto, it was published on the eve of events it predicted but, unlike Marx’s famous text, it was widely read. More importantly, a version of its main injunction – “find each other and act” – was certainly what lay behind the surge of activists into Labour in 2015-17.

Agents for change … Occupy Wall Street protesters in New York, 2011. Photograph: Spencer Platt/Getty Images

One of the critical factors in the British left’s bounceback was that it had never fully accepted postmodernism. Instead – through writers such as Mark Fisher, Terry Eagleton and Roy Bhaskar – it had maintained a commitment to philosophical materialism: that a world exists beyond our senses; that it can be changed; and that human beings have agency. In the revival and modernisation of that standpoint, David Graeber’s Debt: the First 5,000 Years stands as a key achievement. Graeber showed that a historical method derived from Marx could be applied to new anthropological evidence to explain one of the most pressing facts of modern economics: the strangulation of economic dynamism by debt.

If there is a single book that embodies the activist left’s turn towards electoral politics it is Pablo Iglesias’s Politics in a Time of Crisis. Others had talked about storming the political system by creating a new formation; by the time it came out Iglesias had done it, supplanting PSOE, Spain’s traditional socialist party as the main left force in several cities. Iglesias – like Davies – identified the hollowing out of democracy by market forces as the issue that would allow radical leftism to win new support among millions of people.

Finally, the convergence of distinct social movements with a traditionally male-dominated socialist left would not have been possible without the work of Kimberlé Crenshaw, who pioneered intersectionality theory. Intersectionality has become the most influential framework for understanding the multiple, overlapping oppressions we face, and their relationship both to colonialism and economic exploitation. Once it was widely taught in universities it became the unacknowledged terrain on which social movements previously at war over their own primacy could begin to work together. Surprisingly, we will have to wait until 2019 for Crenshaw’s definitive collection, On Intersectionality: Essential Writings, but her more specific studies are widely available. And in the meantime, as they say, la lutte continue.