Everyone who rebels against capitalism is motivated by a vision of a better, more just society. From Martin Luther King's "dream" to the way that the Occupy movement created assemblies designed to demonstrate more democratic forms of organising, to workplaces run without bosses in revolutionary Egypt to student occupations where people discuss and fight for the education free of the fetters of profit-making, people don't just get fed up with the way things are - they think about ways to organise the world differently.
These kinds of ideas are part of a long and proud history of people who have rejected the barbarity of capitalism. Freidrich Engels' pamphlet, Socialism: Utopian and Scientific, summarised - and criticised - some of the most sophisticated thinkers to reject the cruelty of the Industrial Revolution and argue for a different way of organising society. Engels dubbed these thinkers - Comte de Saint-Simon, Charles Fourier and Robert Owen - the "utopian socialists".
These three were strongly influenced by the French Revolution that began in 1789. The French Revolution brought the bourgeoisie - the capitalist class - to power against the old aristocracy, but did so by mobilising popular support and unleashing radical ideas of liberty and equality.
Engels wrote: "The Revolution was the victory of the 3rd estate - ie, of the great masses of the nation, working in production and in trade, over the privileged idle classes, the nobles and the priests. But the victory of the 3rd estate soon revealed itself as exclusively the victory of a smaller part of this "estate", as the conquest of political power by the socially privileged section of it - ie, the propertied bourgeoisie".
Saint-Simon's arguments were framed as an attack on the "idlers" - the lazy upper classes. He included among the "workers" factory owners as well as their employees. Nonetheless, his main sympathies lay with the poor.
Charles Fourier took a more forensic look at the conditions of early capitalist society. He mercilessly compared the high-minded rhetoric of the bourgeoisie, who liked to pose as the guardians of enlightenment ideals and civilised behaviour, to what life was actually like for most people. He saw history as moving through stages - from savagery, to barbarism, the patriarchate and civilisation (i.e. capitalism). Like the philosopher Hegel, he argued that history was impelled forward by contradictions. Capitalism simultaneously produces sparkling wealth and grinding poverty, to the extent that Fourier argued that "under civilisation poverty is born of superabundance itself."
Robert Owen was a factory owner. As such he glimpsed the way exploitation worked - observing that although factory workers were producing more wealth than ever before, they lived wretched lives because the capitalist class was siphoning off a surplus.
Owen agued that it was the working class who that produced the wealth under capitalism. This is an important insight, because it means that workers are not merely passively recipients of ill treatment, but are in fact the force that continually reproduces capitalism through their labour. If they can do that, then they also have the potential to bring capitalism to a grinding halt.
Because they took the side of the poor and the working class, Saint-Simon, Fourier and Owen wanted to create an alternative social system. So Owen famously created a cotton mill in New Lanark, where workers were better paid, and had access to good education for their children and social housing. The trouble was that such projects ended up reproducing the evils they were trying to trump. Owen still had to make a profit and soon realised that despite his good intentions, "the people are slaves at my mercy".
Engels embraced the utopians socialists' criticisms of the system, but was determined to push their analysis further to show how the working class could act to dismantle class society. It wasn't enough to show that the system was irrational and unfair - socialist needed to be able to show how it could be got rid of. Workers' power lies at the centre of capitalist production, not in attempting to craft an ideal alternative elsewhere.
As Owen later discovered when he threw himself into the early trade union movement and the Chartist uprisings, the collective centrality of the working class in capitalist production sows the seeds for radically democratic forms of organising. In the self-activity of the working class, Marx and Engels saw the bridge between the material conditions of capitalism and the ideal of a socialist future.
Marxists are idealists in the sense of championing ideals of democracy and liberation that capitalism is systemically incapable of upholding, but, crucially, we're also materialists in that we see the potential for socialism rooted in the structure of capitalist society.
This is why Engels praised the emancipatory vision of the utopian socialists, while sharply criticising their abstract notions of how capitalism could be overcome.
You can't transform society with the power of a beautiful daydream; but nor can you hope to succeed without one.