Cass Sunstein’s #Republic: Divided Democracy in the Age of Social Media is very timely, as we all, horrified, watch the American republic splinter ever more irreparably since the election last November. The book links the literature on filter bubbles and social media dynamics with the actual political impact in the US context, and the constitutional implications.

It cites the growing empirical literature on political polarisation as a result of the spread and increasing use of social media, especially Facebook. (Of course, conventional media have contributed to the polarisation as well – there are some empirical studies such as this one.) Some of the figures Sunstein cites are startling, such as the polling showing that both Republicans and Democrats have growing increasingly likely to express “displeasure” if their child were to marry someone with the opposite political affiliation (49% and 33% respectively in 2010, up from 5% and 4% in 1960, presumably higher still now). This far exceeds the “displeasure” expressed about inter-racial relationships.

Much of the book concerns the scope for deliberative democracy, or getting people to talk to each other and talk through problems. Technology could in principle enable this, although it currently does the opposite. At the same time, the other occasions on which we would all ‘meet’ different kinds of people, from different classes and races, and different opinions, have shrunk. There is more social sorting in real life. The conventional broadcast media are being displaced, and narrower themselves. (Not to mention now being under attack by Trump and Bannon.) Sunstein isn’t too starry eyed about democracy, though: “For many political questions, what matters is getting the facts straight, and for that you need experts, not deliberative opinion polls.” Hooray!

Communications and the media are exceptionally important in a democracy (cf Amartya Sen) and are at the epicentre of the current maelstrom of populism. I was interested in Sunstein’s emphasis on the importance of media ‘solidarity goods’, a special form of merit good that promotes social interaction, debate, understanding, a sense of shared citizenship and solidarity. He suggests solidarity goods are essential to build social capital.

The book resists the temptation to offer quick fixes – there aren’t any. Instead it underlines the priciples of any measures that might make things better: exposing people to material and ideas they wouldn’t otherwise choose or experience; ensuring citizens have a range of common experiences; ensuring policy debates have substance – ‘expertise’. It’s clear to me there are some sharp questions about the regulatory framework governing social media and the online world in general, questions regulators have been pretty keen to avoid so far. It’s time for them to do so now.

I just finished (re-)reading Amartya Sen’s Collective Choice and Social Welfare. The parenthesis isn’t because I can’t remember but because the original 1970 book has been republished with a chunky new section. It isn’t an easy read, even with the corralling of the technical proofs into alternate, starred chapters. Sen addresses the dilemma raised by Arrow’s impossibility theorem and the wider family of impossibility results, which state that a few totally reasonable-seeming assumptions about principles of social choice end up with no decision rule able to satisfy them. The technical language is that between them the assumptions – transitivity, independence of irrelevant alternatives, unrestricted domain, the Pareto (or unanimity) principle, and non-dictatorship – leave a null set. I’ve always thought of it in the shorthand of there being unavoidable conflicts/trade-offs/dilemmas in social choice. Sen shows that for many social choice questions, the assumptions are too restrictive. ‘Unrestricted domain’ means throwing away relevant information; the Pareto condition forbids interpersonal comparisons such as between the rich and the poor. He argues that welfare economics has been impoverished by the Lional Robbins diktat that interpersonal comparisons could not be permitted: it is bizarre that the subject has had so little to say about the distribution of resources and incomes, self-hamstrung for decades.

The additional chapters extend the original and present in a more rigorous manner some of the material in Sen’s The Idea of Justice. There’s a timely chapter on democracy: “Given the mixed bag of results that we can actually get from majoritarian democracy, its defence, important as it is, needs to be seriously supplmented by probing scrutiny of its limits and conditionality.” This written after last November’s US Presidential election.

Not a book for the general reader – The Idea of Justice is a better presentation of Sen’s important work for that audience. But economists should have read Collective Choice and Social Welfare, especially those working on or in public policy. For all its logical abstractions, this is a very practical book.

It’s fair to say the average economist doesn’t pay much attention to sociologists, but to the extent that (s)he does, Mark Granovetter will be a familiar name. His concept of the distinct roles of ‘strong’ and ‘weak’ ties has become widely-cited in the economics literature. Now Granovetter, a Professor of Sociology at Stanford, has published a new book – intended as the first of two volumes – aiming at a synthesis of his views on how the economy and society are enmeshed with each other (it’s out in 2 weeks, can be pre-ordered now)

. Society and Economy: Framework and Principles, sets out at a high level of abstraction definitions and relationships between concepts such as trust, power, norms, values, as they relate to economic decisions and actions.

The book starts out by quite fairly skewering the ‘Just So’ character of some economists’ uses of sociological concepts to explain how economic norms or institutions have come about. The book suggests that if economics wants to use a concept such as ‘social norm’, then it must engage with questions of how norms come about, which will involve cognition and emotion and social relations. Economics has of course started to dabble in psychology with the ‘behavioural’ revolution, but in the limited sense of simply noting behavioural regularities. Here Granovetter echoes Daniel Hausman (Preference, Value, Choice and Welfare) in arguing that it “does not seem a good recipe for scientific progress” to claim that how people reach economic decisions, or how groups settle on social norms, is simply outside the domain of economics.

If this seems a bit high-fallutin, just consider how much influence social norms have on outcomes. In the 1970s, for corporate executives to pay themselves many hundreds of times what they paid their average employee lay outside the ‘moral economy’ of the times; within a generation that norm had shifted entirely. Surely it is important for economists to understand how that came about?

The book has a particularly interesting chapter on trust, which notes that the outcome of trusting behaviour can arise for different reasons. Granovetter argues that many researchers define trust narrowly to be trust due to their favourite reason, whether that’s an internal psychological state, or an expectation of reciprocal behaviour, or risk-taking with regard to others’ behaviour for some expected benefit.

The promised second volume will apply the concepts defined and analysed in this first volume to specific topics such as corporate governance, organisational forms, and corruption. That’s something to look forward to – this first volume is pretty abstract as it concerns definitions and methodological debates in the literature. Still, the challenge to economists is a fair one, I think. We don’t all have to become competent psychologists or sociologists, but I agree that somehow economics does have to take up the methodological challenge of making sure our borrowing of concepts such as trust or norms is meaningful.