1. Introduction
Market exchanges and gifts rest upon different belief systems, norms and values with a diversity of cultural and historical dimensions. Markets and gifts are examples of institutions that make up the institutional complementarity and diversity of modern economic systems (Negru, Reference Negru, Garnett, Olsen and Starr2009).
Although gift-giving embodies rules, customs, conventions and principles of action, thus constituting an institution, it has been somewhat neglected even by institutional economists, with exceptions such as Geoffrey Hodgson (Reference Hodgson1988) and Janet Landa (Reference Landa1995). Hodgson (Reference Hodgson1988) discusses the gift within a framework of formal and informal institutions that govern the space of market exchange. Landa (Reference Landa1995) draws on a conception of gift such as the symbolic Kula Ring exchange and shows that this can be seen as an efficient institutional arrangement for exchange.
The purpose of this symposium is to explore and to begin to fill the gap left by institutional research concerning the analysis of the gift and to advance a conception of the gift as an institutionalised transfer. The articles collected in this symposium indicate a research path for institutional research on gifts. The articles in this symposium proceed from theoretical–conceptual to more empirical studies. By reflecting on the contributing articles, in this introduction to the symposium we try to address the issue of how gift and gift-giving studies can be relevant to the study of institutions and vice versa as well as indicate a possible research path for institutional research on gifts.
2. The concept of the gift: Mauss and beyond
Since Mauss's well-known Essai sur le Don first appeared in 1925, gifts and gift exchange have often been studied and theorised within the field of anthropology, often the gift being portrayed as a non-market alternative to capitalism (Polanyi, Reference Polanyi1944). The Maussian conception of the gift rests on the assumption that people give because they expect to receive, and that people respond to a gift because they will fear others will stop bonding or interacting socially. The gift is based on three obligations: the obligation to give, to receive and to reciprocate, where the maintenance of social ties is considered to be essential (Mauss, Reference Mauss2002 [1925]).
In the Maussian tradition, Godbout and Caillé (Reference Godbout and Caillé1998: 20) define the gift as ‘any exchange of goods and services with no guarantee of recompense in order to create, nourish or recreate social bonds between people’. According to Caillé (Reference Caillé and Vandevelde2000: 47), the gift is: ‘every allowance of goods and services made without a guarantee of return, with a view to creating, maintaining or regenerating the social bond. In the relationship of the gift, the bond is more important than the good’. From the perspective of this tradition, the gift facilitates social relationships of friendship, helps avoiding war and destruction through rivalry and ensures social order. Thus, the gift serves a useful function by reducing uncertainty in some important social interactions. If we are to interpret the three Maussian obligations as underpinned by rules and customs then, this definition of the gift would be compatible with Hodgson's approach to institutions (Reference Hodgson2006: 2), where these are defined as ‘systems of established and prevalent social rules that structure social interactions’. In modern times, the institution of the gift has evolved culturally and socially and has been subject to many transformations. Some forms of gift are voluntary, free, disinterested and involve no return (e.g. gifts to beggars). This suggests we need a better definition of the gift, adapted to modern times and large-scale societies mainly made up of relationships among strangers.
Elder-Vass (Reference Elder-Vass2019) addresses the fundamental issue of how we should define the terms gift and giving in a way that acknowledges contemporary gift-giving. Elder-Vass notes the neglect of the analysis of the gift by both mainstream and heterodox economics. Rare but notable exceptions in economics are by Boulding (Reference Boulding1973) and Mirowski (Reference Mirowski, Mises, Amariglio and Ruccio2001). Elder-Vass argues that such definitions exclude many phenomena commonly understood as giving, as in the cases, for example, of gifts to strangers or charitable giving for environmental or animal causes, where no social bond can be created and no obligation to return can be expected. It is misguided to analyse gifts in contemporary settings in terms derived from anthropological discussions of very different kinds of smaller and/or archaic societies. Indeed, contemporary heirs of Mauss have strived to go beyond the studies of the gift in archaic societies and have acknowledged that the gift between strangers is a typical gift in modern times (Caillè, Reference Caillé1998; Godbout and Caillè, Reference Godbout and Caillé1998; Silber, Reference Silber, Wendy and Nicholas1998).
Hence, Elder-Vass (Reference Elder-Vass2019: 7) proposes a definition of gift-giving and the gift as the ‘practice of voluntarily transferring goods or services to another party without any compulsory requirement for a transfer in return’, although he has left unanswered questions such as how and when gift and gift-giving can become institutionalised.
In their article, Cedrini et al. (Reference Cedrini, Ambrosino, Marchionatti and Caillé2019) propose a reading of Marcel Mauss's insights into gift exchange using insights from institutional economics and elsewhere. They put forward two basic claims. On the one hand, the gift is to be interpreted as (essentially) an institution arising from the self-transcendence of social relationships that gifts themselves are expressly designed to create and according to which individuals orient their behaviour. This perspective, originally developed by Anspach (Reference Anspach2002), shows how institutions emerge as a ‘third term’ in a bilateral relationship between two parties engaged in an exchange. Also, by relying on Hodgson's (Reference Hodgson2004) rehabilitation of institutional economics in the tradition of Thorstein Veblen (Camic and Hodgson, Reference Camic and Hodgson2011), they try to rethink the relationships between market and gift exchange.
Both Elder-Vass (Reference Elder-Vass2019) and Cedrini et al. (Reference Cedrini, Ambrosino, Marchionatti and Caillé2019) discuss the Maussian definition of the gift and its implications for subsequent studies. On the one hand, Cedrini et al. present an argument of the ‘necessity of an institutional approach to economics’ that derives from a certain reading of Mauss. For Cedrini et al. systems of gift exchange ‘in their purity’ presuppose the existence of three institutional rules: the obligation to give, receive and return. On the other hand, Elder-Vass relies on Testart's (Reference Testart, James and Allen1998) critique of this definition implying an obligation and reciprocation: the obligation to reciprocate is a nonessential characteristic of gift and gift-giving. At the heart of these divergences there remain different conceptions of ‘obligation’, ‘freedom’ and their reciprocal tension, worthy of further explorations, as we shall see later.
Despite being overlooked in some institutional approaches, gift-giving is a social norm and an institution, governed by certain rules, which has enjoyed different connotations within different societies, across time. Before Mauss (Reference Mauss2002 [1922]) distinguished between economic and social exchange and used the example of exchange in the Kula Ring to point out that the gift is a type of social exchange. He saw power and custom, rather than utility maximisation as driving social relationships. The gift, as an institution, brings with it a set of values that govern the human relationships in society. The relevance of the gift and its roles in different phases of economic development, for any school of thought examining economic systems, is clearly visible in the contributions to this symposium.
3. Empirical institutional analysis of the gift and methodological implications
There is an institutional analysis of gift-giving in the articles in this symposium by Goodman and Herzberg (Reference Goodman and Herzberg2019) and Keith Taylor and Goodman (Reference Taylor and Goodman2019). They are also carefully executed empirical institutional analyses of two very relevant case studies of gift giving, based on dense case descriptions and the interpretation of contemporary and historical documents.
Goodman and Herzberg (Reference Goodman and Herzberg2019) – ‘Gifts as governance: Church Welfare and the Samaritan's Dilemma’ – scrutinise the welfare programme of the Church of Jesus Christ of Latter-day Saints in the USA and focuses on how the church devised institutions to deal with the Samaritan's dilemma (Buchanan, Reference Buchanan and Phelps1975; Gibson et al., Reference Gibson, Andersson, Ostrom and Shivakumar2005; Schmidtchen, Reference Schmidtchen, Brennan, Kliemt and Tollison2002; Skarbek, Reference Skarbek2016) of never ending and growing financial demands by claimants who have come to the conclusion that the church administrators will under no circumstances withdraw their assistance. The authors argue on the basis of a consequentialist, rational choice, game-theoretic framework and they consider the best enabling and constraining incentive structure for welfare recipients by the church, while the mechanisms described are actually strict social monitoring and control accompanied by a strong set of shared values and religious ideology which would suggest at least in part a deontological interpretation. Thus, there is another undercurrent different from the rational choice framework in the article. This is probably due to the influence of Boulding's (Reference Boulding1973) grants economics on the interpretation of the case. The authors also highlight parallels in their themes and findings with sociological and anthropological work on gift exchange and state: ‘we emphasize how gifts, social norms, culture, and ideology are mutually reinforcing’ (Goodman and Herzberg, Reference Goodman and Herzberg2019: 2). Moreover, they suggest in their conclusion that more detailed qualitative work – participant observation and interviewing the welfare recipients and church administrators – could further the investigation into the motivation for behaviour on both sides of the Samaritan Dilemma and enrich the insights of how the institutional mechanism works.
Taylor and Goodman (Reference Taylor and Goodman2019) – ‘The stakeholder-empowering philanthropy of Edward Filene’ – develop a historical case study that addresses how the free-rider problem may hamper cooperation. The argument is built on the interpretation of historical documents and describes the important role played by Edward Filene's empowering philanthropy in creating and sustaining a whole raft of thriving building societies across the USA. The institutional analysis shows convincingly how grants and philanthropy are used to overcome social dilemmas and create self-governing organisations which would otherwise be undermined by debilitating collective action problems and unsurmountable transaction costs. While the study focuses on individual incentives, there is also an alternative ontology of cultural cohesion, solidarity, community values, common bonds and the spirit of volunteer work apparent in the case description.
The fifth research article of this symposium is also strongly empirical in nature. Hudik and Fang's (Reference Hudik and Fang2019) ‘Money or in-kind gift? Evidence from red-packets in China’, focuses on Chinese social norms and advances a model of gift-giving based on social conventions. In particular, this paper focuses on the acceptability of money or red packets in China and poses the following question: ‘When do Chinese consider gifts appropriate?’ (Hudik and Fang, Reference Hudik and Fang2019: 2). The relationship between the giver and the recipient, alongside various occasions for gifting are of significance for the acceptability of certain forms of gift-giving. Two sizeable surveys were carried out. In the first survey, the authors focused on gift-giving norms in general for various occasions and different types of relationships. The second survey has concentrated on two important Chinese occasions where gift-giving behaviour takes place: The Chinese New Year and birthdays. Contrary to other studies, the authors find occasions essential in determining the forms of gift-giving behaviour and although they focus on the role of conventions in determining forms of gift-giving, they conclude that gift forms are influenced by multiple causal factors. Red-Packets or money gifts are seen as a ritualised gift, part of a ceremonial exchange between individuals, while gift vouchers are found to be the least popular form of gift. So, cultural context matters.
Reflecting on the methodological implications of these three empirical contributions to the symposium, one may ask: what kind of empirical research of gift giving is most fruitful in demonstrating the institutional framework underlying such behaviour? The first empirical study by Goodman and Herzberg (Reference Goodman and Herzberg2019) is founded on interpreting texts issued by the Church of Jesus Christ of Latter-day Saints and a historical study, the second inquiry by Taylor and Goodman (Reference Taylor and Goodman2019) is based on interpreting historical studies and archival documents on the role of Edward Filene in his support of cooperatives. The third study is based on a survey. While limited, this shows a variety of qualitative and quantitative methods employed.
However, to this day the core empirical method for anthropology in analysing institutional change is ethnography or fieldwork – the dense description of human interaction drawn from a participant observer who tries to keep as open a mind as possible when reporting and interpreting what he or she sees, hears and picks up in other ways (Engelke, Reference Engelke2017: 14). Moreover, in their Economic Anthropology, Hann and Hart (Reference Hann and Hart2011: 8) also emphasise: ‘we are sceptical of evolutionary models grounded in notions of efficiency and abstract individual rationality, and argue instead for a more rounded approach to economic organization that does justice to the material, historical and ethnographic record’. Empirical evidence is recorded in the following way: ‘On the basis of this participant observation the anthropologist amasses data, often in the form of diaries and fieldnotes’ (Hann, Reference Hann2000: 41). Ostrom (Reference Ostrom1990) has championed the use of anthropological field work to inform institutional economic theory, but there are also industry and problem specific ethnographic studies which illustrate such fruitful interdisciplinary collaboration (Graeber, Reference Graeber2011; Zaloom, Reference Zaloom2006). As suggested by Goodman and Herzberg (Reference Goodman and Herzberg2019) at the end of their article, one may ask whether employing ethnographic studies may not further enhance our institutional understanding of the gift.
Voigt (Reference Voigt2013) also suggests more application of qualitative research methods. This is apparent when one looks at the empirical case studies referred to by him to underpin his arguments and which are based on ethnographic field work, surveys, in-depth interviews and other qualitative methods (for instance Bernstein, Reference Bernstein1992, Djankov et al., Reference Djankov, LaPorta, Lopez-de-Silanes and Shleifer2003, Ellickson, Reference Ellickson1986, de Soto, Reference de Soto1990). Moreover, he states that: ‘factually observed behavior needs to be measured’ (Voigt, Reference Voigt2013: 17) and that surveys without ethnographic field research conducted in parallel are unreliable (ibid.: 18) or not ‘objective’ (ibid.: 19). So, inspired by the sociological, historical and anthropological influence on the empirical studies represented in this symposium, one may wonder, whether a focus on the gift may lead to a stronger emphasis on and even richer variety of qualitative research methods employed by institutional researchers in future.Footnote 1
The gift has iconic status for theory construction in social anthropology. Mauss (Reference Mauss2002 [1925]) who never did any ethnographic research himself took Malinowski's (Reference Malinowski2002 [1922]) observation of the Kula Ring and numerous other examples, from a diverse range of cultures dispersed widely in time and space, to develop his theory of the gift and its tendency to create reciprocity, to then draw conclusions for the industrial society of France in the 1920s. Though this interpretation of the Kula Ring has been critically examined and convincingly questioned (Landa, Reference Landa1995; Testart, Reference Testart, James and Allen1998: 101–102) and led to other critical reviews, it has nonetheless inspired scholars in diverse social sciences (Bataille, Reference Bataille1988 [1967]; Boulding, Reference Boulding1973; Dillon, Reference Dillon1968; Perroux, Reference Perroux1961; Polanyi, Reference Polanyi1944, Reference Polanyi and Dalton1968a, Reference Polanyi and Dalton1968b) as well as decades and even centuries of methodological battles fought within anthropology (Firth, Reference Firth1967; Sahlins, Reference Sahlins1972) and paradigm wars between anthropologists and economists (Hann and Hart, Reference Hann and Hart2011; Marchionatti and Cedrini, Reference Marchionatti and Cedrini2017; Polanyi, Reference Polanyi and Dalton1968a, Reference Polanyi and Dalton1968b). So, when institutional economics engages with analysis of the gift, this poses the question whether empirical methods employed by anthropologists could be used for theory development in these analytical inquiries.
4. Institutionalised gift-giving: lines of tension and future explorations
The reason why it is interesting to reflect on the possibility of a cross-fertilisation between the studies on gift and those on institutional economics is because both perspectives are partly overlapping, have areas of tension and critical issues not sufficiently studied. Collaboration could be fruitful. We limit ourselves here to indicating two particularly important problems for both perspectives: the problematic relationship or tension between obligation and freedom on the one hand, and between state and market on the other. In particular, two major institutions of modernity are at the heart of these tensions: the welfare state and the third sector. It is no surprise that two contributions to this symposium focus on case studies from the third sector: Goodman and Herzberg (Reference Goodman and Herzberg2019) as well as Taylor and Goodman (Reference Taylor and Goodman2019).
Furthermore, focusing on these institutions underlines the problem of the relevance of the gift phenomenon in modernity, and, at the same time, to avoid an understanding of this phenomenon as merely belonging to the sphere of private present-giving (Cheal, Reference Cheal2015).
To understand the problematic relationship between obligation and freedom, it is useful to ask: to what extent can gift-giving practices and norms of reciprocity be institutionalised and even legally enforced without losing some of its characteristics such as spontaneity, freedom and voluntariness?
Anthropological studies have remained trapped in an unfruitful contrast between those who consider the social state's redistribution mechanisms and welfare policies as a modern system of gift circulation (Mauss, Reference Mauss2002; Titmuss, Reference Titmuss1970), and those upholding that the state's institutionalised redistribution is incompatible with any idea of the gift (Godbout and Caillè Reference Godbout and Caillé1998: 51–64).Footnote 2 The basic argument of the latter can be formulated as follows: if the citizen has a duty to pay taxes, and if the freedom implicit in voluntary giving implies the freedom to give and not to give, then paying taxes is not a gift. As Godbout and Caille argued, criticising Titmuss: ‘a gift that's imposed is not a gift’ (ibid.: 60). We may call this issue the gift/duty dilemma. How to resolve it?
One way to rethink this dilemma is to bring the problem of legal–political obligation into the institutional discourse: why follow a rule or obey the law or authority? It would seem that while institutional economic studies neglected, with a few exceptions, the problem of obligation, anthropological studies, instead, ended up emphasising Mauss's insistence on the universal obligation to reciprocate too much. In this regard, though we may agree that one of Mauss's main concern was to show that ‘human institutions everywhere are founded on the unity of individual and society, freedom and obligation, self-interest and concern for others’ (Hart, Reference Hart2007: 9), the mere insistence on the fact that gift conjugates ‘freedom and obligation’ risks overshadowing their always problematic tension.
In particular, the universal obligation to reciprocate is not only empirically ‘false’, but also it obfuscates the different nuances that are given in the range of types of obligation, from moral to legal obligation and related sanctions (Elder-Vass, Reference Elder-Vass2019; Testart, Reference Testart, James and Allen1998). On the other hand, there is no a priori reason that allows us to exclude that a moral sanction is perceived, by the individual, as heavier or more compelling than a legal one.
Furthermore, although it is true that institutional economics has dealt with the different types of sanctions and enforcement mechanisms (Dequech, Reference Dequech2006; Voigt, Reference Voigt2013), it is also true that conceptions of institutions as constraints (see Hodgson, Reference Hodgson2006 on North) and norms as incentives (or rewards and punishments) has reduced the problem of obligation to a cost-benefit calculation. This is partly due to behavioural assumptions built on the utility maximising individual. This model, evades the possibility of rule-following behaviours based on habits, morality, sense of duty, justice, beliefs or perceived legitimacy of authority (Hodgson, Reference Hodgson2013, Reference Hodgson2014; McCloskey, Reference McCloskey2015; Searle, Reference Searle2001; Sen, Reference Sen1982). The dominance of utility maximisation helps explain why mainstream economics has largely neglected the gift phenomenon and its institutionalised forms.
The literature on homo reciprocans (Fehr and Gächter, Reference Fehr and Gächter1998, Reference Fehr and Gächter2000; Fehr et al., Reference Fehr, Fischbacher and Gächter2002) is more promising, in so far as it has shown how people can obey or disobey the law and respond to the behaviour of other subjects starting from a certain sense of duty or fairness or reciprocity, even if this is ‘costly’ for them.
Not surprisingly, another way to rethink the welfare state, redistributive policies and the problem of their legitimacy is to try to re-read them in the light of studies on reciprocity (Bowles and Gintis, Reference Bowles and Gintis2000; Goodin, Reference Goodin2002; Ullrich, Reference Ullrich2002; Wax, Reference Wax2000). Above all, some studies have tried to conceptualise the welfare state as an economic arena of redistribution ‘institutionalized’ by different types of reciprocity norms as ‘norms of social exchange’ according to different historical–cultural types of welfare regimes (Mau, Reference Mau2004).
This approach seems to us to be promising, even if it deserves an analysis in itself to understand how these reciprocity norms are internalised and perceived as legitimate, and how the tension between freedom and obligation operates at an individual and social level as well as at an institutional level.
As for the tension between state and market, the questions are: to what extent does the state/market dichotomy allow us to grasp the identity of the third sector as an institutionalised sphere of the gift? And how do third sector organisations interact with the state and the market?
Distinguished scholars have long insisted on the limits of this dichotomy in understanding society, the economy and institutions (North, Reference North1990, Reference North2005). Ostrom, in particular, urged us to look 'beyond markets and states' (Ostrom, Reference Ostrom2010) given its incapacity to grasp the nuances, the specificity and the variety of hybrid cases in between state and market. Sociologists and anthropologists (Adloff and Mau, Reference Adloff and Mau2006; Godbout and Caillè, Reference Godbout and Caillé1998) have long recognised the relevance of the third sector as the arena par excellence that mediates the extended circulation of gift in modern society. But these approaches have rarely learned from each other.
The state/market dichotomy has not helped much to grasp the specific identity of the third sector. The very labelling as ‘third sector’ marks it as being perceived as either a residual of the state and the market, or merely as functional to the state and the market, i.e. designed to make either one or the other work well (Donati, Reference Donati, Rossi, Boccacin and Anheier2008). Not to mention the concept of ‘non-profit’ which, on the one hand establishes a negative identity – the non-profit – and on the other hand stems from an US American cultural horizon from which it originates, and does not capture the historical–cultural differences of the types of institutions that make up the third sector, especially those developed on the European continent.Footnote 3
The challenge that the third sector therefore poses to the institutional economics is to be able to think of its identity through the logic of the circulation of the gift, and beyond the state and the market. However, this does not mean thinking of it as isolated from the state and the market.
Indeed, some studies on the relationship between the welfare state and third sector organisations have focused on their relationship in terms of conflict or cooperation or as institutional crowding-out or institutional crowding-in. For example, critics of the welfare state as a modern form of gift circulation believe that the welfare state is always susceptible to perverting or crowding out the very idea of gift or even destroying the ‘true’ gift circulation occurring at the level of the civil society. In this perspective, the true actors of such circulation are the voluntary or third sector, associations, social networks and families, and not the state (Godbout and Caillé, Reference Godbout and Caillé1998: 51–64). However, to pose the problem in terms of a pure trade-off between the third sector and the welfare state, and between the third sector and the market, seems a little sterile and reductive.
It should first be clarified whether it is a normative or a positive analysis. In the first case, one should at least make explicit and then analyse the values at stake or the values that one wishes to defend, for example the values of civil society and the third sector, or autonomy or individual freedom, the freedom to donate or to associate, etc., against the state or against the market. But this way of thinking will also have to pay attention to the fact that in many cases, the third sector is highly dependent on the financing that keeps it alive, both from the state (e.g. in European countries) and from the market (e.g. in the United States). And this is also one of the (not trivial) reasons for which it does not make much sense to contrast these spheres or to read them in the light of other simplifying dichotomies, such as the ‘social’ (=the ‘gift’ provided by the ‘state’ or the ‘third sector’) and the ‘economic’ (=provided by the ‘market’), especially if one considers that some types of third sector institutions as social enterprises are ‘perfect’ hybrids in between the ‘social’ and the ‘economic’. A generalised criticism of the market or the state risks cutting off the branch on which the third sector is sitting.
Moreover, empirical inquiries of ‘crowding out’ or ‘crowding in’ phenomena produced very different results depending on the historical context in which they were carried out (for a survey of this literature see Pestoff, Reference Pestoff2008: 225ff) thus, showing the weight of the cultural background in which both the welfare state and the ‘other’ spheres of gift are located. Again, therefore, this should be a fertile ground for studies conducted by institutional economists.
Also, we need to better understand the dynamics of complementarity and conflict between the third sector and the state as well as the market. There are a few institutional economic studies on the third sector that have focused on these aspects, especially emphasising the cases of complementarity (Valentinov et al., Reference Valentinov, Hielscher and Pies2015) or synergy (Christoforou, Reference Christoforou2010). Other studies (Amendola et al., Reference Amendola, Garofalo and Nese2011), on the other hand, have attempted a more explicit institutional conceptualisation of the third sector drawing inspiration from Aoki's definition of institutions (Reference Aoki2001, Reference Aoki2007) as a bundle of formal rules and subjective shared beliefs, and showing the substantial complementarity of the third sector to the state and to the market and how it contributes to promoting a culture of cooperation, altruism and solidarity.
5. Conclusion
A central proposition advanced in this introduction and in the symposium is the possibility of establishing a new research domain aimed at integrating institutional studies and gift studies, based on the definition and interpretation of the gift as an institution. In this paper, we not only summarised the contributions of the five research articles comprised in it, but also sketched the main aspects of this research domain such as its subject matter, its methodology and the tensions between gift, gift-giving and institutions in particular relevant areas such as the third sector and the welfare state.
The gift is essential for economic and also for institutional analysis for two reasons: we need a better understanding of human behaviour in economics and we need to enhance the potential of the institutions of the gift in explaining processes of economic development, alongside markets and the state.
We have explored this possible way of integration between these fields of study, and now a new path of research seems to open up before us. We could tentatively call it ‘Institutional Economics of Gift’.
Acknowledgements
This article is the result of a common effort and a continuous dialogue between the three authors. More in particular, Ioana Negru has written Sections 1 and 2, Stefan Kesting Section 3 and Paolo Silvestri Section 4, while abstract and conclusions are the result of a three-handed writing. The authors wish to thank Professor Geoffrey M. Hodgson for helpful comments on various drafts of this Introduction.
Financial support
Ioana Negru acknowledges support by Lucian Blaga University of Sibiu & Hasso Plattner Foundation research grants LBUS-IRG-2019-05. Paolo Silvestri acknowledges funding from the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme (FP7/2007-2013) under REA grant agreement no. 609305.