An example in politics could be the US and its stance on the Kyoto agreement.
On the Bush years, US wanted nothing to do with it. Obama promised to change that. Bourgeois media or history books would view that as a proof of Obama being more progressive, in touch with his era and its problems etc.
A materialist would argue that a person's behaviour (or a rulling class' policies and stance on matters) isn't something that exists independently of this world, the material sphere, and the economy, which is the base of everything.Instead, it is born out of it. Also, that it is the outcome of many "collisions" between groups that see they have conflincting interests as they interract with each other.
In that case, Bush acted in a certain manner not because he believed those saying there is no global warming, but because he represented the interests of Big Oil and polluting industries. US dependence on that type of production was what led to the middle east wars.
Obama on the other hand was backed by that part of the bourgeoisie that sees in the so called "green economy" a great profit opportunity. He was also against the war in Iraq as his sponsors, the capitalists that hired him to do their bidding and whom he represented, wouldn't have much to gain from it. This side grew in strength really fast as only recently renewable forms of energy became financially viable and as science is making great leaps.
So, what did change wasn't that a more progressive man walked into office but that the part of the bourgeoisie that sees a bigger chance for profit in "going green" has for the time being the upper hand in the ongoing "struggle".
The procedure to use it seems to be looking at the right place, which is the economy and the social relations that arise from it.