to be monitored, ad infinitum). For Alchian and Demsetz, the firm, therefore, is an entity that brings together a team that is more productive working together than at arm's length through the market, because of informational problems associated with monitoring of effort. In effect, therefore, this is a "principal-agent" theory, since it is asymmetric information within the firm which Alchian and Demsetz emphasise must be overcome. In Barzel (1982)’s theory of the firm, drawing on Jensen and Meckling (1976), the firm emerges as a means of centralising monitoring and thereby avoiding costly redundancy in that function (since in a firm the responsibility for monitoring can be centralised in a way that it cannot if production is organised as a group of workers each acting as a firm). The weakness in Alchian and Demsetz’s argument, according to Williamson, is that their concept of team production has quite a narrow range of applications, as it assumes outputs cannot be related to individual inputs. In practice, this may have limited applicability (small work group activities, the largest perhaps a symphony orchestra), since most outputs within a firm (such as manufacturing and secretarial work) are separable so that individual inputs can be rewarded on the basis of outputs. Hence team production cannot offer the explanation of why firms (in particular, large multi-plant and multi-product firms) exist. Asset specificity For Oliver E. Williamson, the existence of firms derives from ‘asset specificity’ in production, where assets are specific to each other such that their value is much less in a second-best use. This causes problems if the assets are owned by different firms (such as purchaser and supplier), because it will lead to protracted bargaining concerning the gains from trade, because both agents are likely to become locked into a position where they are no longer competing with a (possibly large) number of agents in the entire market, and the incentives are no longer there to represent their positions honestly: large-numbers bargaining is transformed into small-number bargaining. If the transaction is a recurring or lengthy one, re-negotiation may be necessary as a continual power struggle takes place concerning the gains from trade, further increasing the transaction costs. Moreover, there are likely to be situations where a purchaser may require a particular, firm-specific investment of a supplier which would be profitable for both; but after the investment has been made it becomes a sunk cost and the