The rise of Aristotle
For me, one of the biggest 'big ideas' of our time is the return of Aristotle, and the concomitant move beyond liberalism (what David Goodhart calls 'post-liberalism') and towards a more Aristotelian conception of the good life and the good society. I've argued that this 'rise of neo-Aristotelianism' began in the 1980s with Alasdair MacIntyre's After Virtue, and gathered pace over the next two decades with the works of Martha Nussbaum, Charles Taylor, Michael Sandel and Amartya Sen, and the trickle-down of this revival of virtue ethics into modern policy thinking, via the likes of Richard Reeves, Geoff Mulgan, Jon Cruddas, Philip Blond and the New Economics Foundation.
For a visual image of this process at work, look at this Google ngram graph, showing the rise in the use of the word 'Aristotle' in Google's database of books since the 1960s. The precipitous rise begins in the late 1980s - as a backlash against neo-liberalism begins and writers start to look for older ideas of personal and civic virtue and well-being. At least...I think that's what's happening.