Florence in the 13th-15th century is the focus of the state and market formation working group at Santa Fe Institute headed by John Padgett, with Duncan Watts (SFI postdoc), David Stark [Eastern Europe], Gernot Grabher [Germany], Woody Powell [US biotech], and Doug White [UCI].
Walter Fontana [chemist, Vienna], a full-time SFI resident researcher, also usually joins the group on regular basis. An assortment of other SFI regulars (see SFI web page) also interact with the group. June is the month of intensive group efforts in 1999.

Summarized below are the phase transitions described by Padgett (1998) for the transformation of family and banking systems (and the birth of the modern financial capital market) in Renaissance Florence, 1200-1500.

My question (DRW): are the phase transitions described by John the result of "exogenous shocks" at the level of changes in state politics, or are they (also?) the result of phase transitions in network evolution?

Florence
firm types and
logic of identity
local interactions: firms, marriage system punctuated orgzn. form
social structural changes
state level politics network evolution
affects logic of identity affects orgzn. form DRW: affects politics?
1200?....-1348 
family regime
large, patrilineal families
fa/son logic of identity
hypergamous alignments rise of popolani (elite) domination  vicious competition of great families "lines" not densely linked by daugher's marriages (they marry down)
1349-1378
guild regime
master-apprentice clusters (neighborhood and guild) and logic of identity deconcentration of firm sizes, biographic traject. (bilateralization?) Black Death depopulation,
neighborhood and guild, popolani partners w/others
elites seized control of the guilds, "solidaristic" local aggregation
interclass partnerships
1380-1433
popolani regime
multi-divisional firms (partners in diff.trades), low cross-industry mobilty, class logic of identity guilds crushed; popolani class endogamy, "family" includes in-laws Chiompi revolt: after which popolani again dominate partnerships elites exiled and exprop- riated, workers republic; quickly overthrown social class, "relinking" into giant bicomponents with local clusters, interlocking directorates, elite intermarr
1434-1494
Medici regime
rentier, separation btwn owners and managers, patronage logic of identity patronage and partner recruitment through the emergent court; relations personalized at top, marketized at base Medici patronage era, previously excluded middle class ("new men") share partnerships "class balancing" control technique of Medici as policy; high level financiers withdraw into state exploitation of strategic holes and central cross-strata links in network, esp. by Medici
Succession of firm-types (partnerships) of Florentine Guilds, especially Banks (summary from Padgett 1998)

John's data on 10,000 marriages are being converted into p-graph format for further network analysis. Hence network k-components and local interactions such as marital relinking patterns can be computed and compared over time.

This is one of the best linkages project applications of the p-graph methodology (DRW) to a large-scale social network, where the theory of emergent phases of small- and large-scale cohesion theory can be studied. In the earliest period of corporate patrilineages and family-run banks as non-transferrable patrimony, for example, social innovation included the invention of hereditary last names. The network structure was one of low density tree-like kinship structures corresponding to lineages that grow over time. The density of inter-lineage marriage ties is also relatively low because of hypergamy, marriage of daughters of the leading families with less know families of much lower rank. As families grew and intermarriages proliferated (1200-1340s) we hypothesize a first transition to locally relinked clusters in the guild regime, and a density transition to a giant bicomponent in the popolani (1380-1433) regime. This second transition would correspond to the emergence of a social class basis for the financially elite (popolani) families.

References:
John Padgett. 1998 ms. Organizational Genesis, Identity, and Control: The Transformation of Banking in Renaissance Florence. Seminar on Social and Institutional Change, Robert Woods Johnson Foundation, Princeton, N.J.
Current draft for Theory and Society (with Paul DiMaggio) entitled "The Social Relations Underpinning Florentine Markets: Evidence from the 1427 Catasto", conference paper presented to the 1997 Economic History meetings and to 1998 ASA meetings.

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