Sandel was arguing, overall, for a 'better kind of politics', one oriented 'less to the pursuit of individual self-interest and more to the pursuit of the common good.'
First he showed that our present politics is too influenced by the ideology that allows markets to intrude where they do not belong - we have drifted 'from having a market economy to being a market society'. In fact not all values are quantifiable or economic, and not every good should be treated as a commodity.
In the second lecture he showed that the right way to value things (for political or other purposes) is to 'figure out the purpose, the end of the social practice in question'. This took him into Aristotle's theory of justice. He concluded that we cannot and should not avoid substantive moral questions in politics - questions of what we mean by the 'good life', which determine the nature of justice. We need a much more open and robust debate about this.
In the third, he applied all this to the question of genetics, and the growing threat of a new 'liberal' or non-coercive eugenics movement, which erodes our fundamental sense of human life and of our own talents and abilities as 'gift'.
Finally, in the fourth lecture, he spoke of the end of 'market triumphalism' and the need for a new philosophy of public life. We need to return to traditions of solidarity and civic virtue instead of trying to avoid moral questions by relying entirely on the mechanism of the market. Economics is not a 'value-neutral science'. The attempt to empty politics of moral controversy (by always trying to be 'non-judgemental') is actually 'corrosive of democratic life'. We should regard ourselves less as consumers and more as citizens.
'So rather than focus on access to private consumption, a politics of the common good would make the case for rebuilding the infrastructure of civic life; public schools to which rich and poor alike would want to send their children; public transportation systems reliable enough to attract commuters from all walks of life; public health clinics, playgrounds, parks, recreation centres, libraries and museums that would, ideally at least, draw people out of their gated communities and into the common spaces of a shared democratic citizenship.'And he concludes that 'the virtues of democratic life - community, solidarity, trust, civic friendship - these virtues are not like commodities that are depleted with use. They are rather like muscles that develop and grow stronger with exercise.' 'A politics of moral and civic renewal depends... on a more strenuous exercise of these civic virtues.'
Well, it seems a bit like wishful thinking in some ways. Very true though! Lets see if the Pope can do better.