Raymond Williams once said: "To be truly radical is to make hope possible rather than despair convincing". Many now feel despair. We feel great loss. The things that we took as given have abruptly gone – like growth.

At such moments hope is key to avoid despair. Our history tells us that these turning points are dangerous moments – if we retreat.

We must contest this turning point. We can still win. My argument is not simply an argument about Labour; this is not about internal issues.

Think for a moment about the Tories. Earlier I talked about how declining economic growth has lost Labour its revisionist mode. But this is the same for the Tories. Camerons's "Progressive Conservatism" was built on the assumption of sharing the proceeds of growth; that the Thatcherite early 1980s resolved all the issues of economics.

Yet when the first economic storm clouds gathered they retreated. Think about what is emerging. Think about how despite the empathy everything coming out from The Centre for Social Justice is punitive. Think about the party of Daniel Hannan. Not some side show but a man whose central philosophy is hardwired into the mindset of the young Tories.

Think about their laboratories in Hammersmith, in Essex and in Barnet. It tells us of the brutality that lies ahead – the notion of "easycouncil"; of social care and housing cuts in west London; of a fundamental assault on local authorities wrapped up in the language of quangos.

Just think of this weekend's stories of regionalised benefits, mass privatisations and across the board cuts. Last week they signalled a moratorium on hew house building. Look who leads their group in Europe. Think and explore the Wisconsin benefits model. Look at the glint in the eye when they talk about cuts, the relish.

Why is it that after a summer in which the Tories have shown their true colours, we have barely laid a glove on them? Why is it that this Thatcherism has grabbed so easily the mantle of progressivism? I would suggest it is because we have lost our language, our empathy, our generosity; because we have retreated into a philosophical framework of the right.

This is an edited extract from the annual Compass Summer Lecture, delivered on Tuesday evening