a good example of this phenomenon is the elimination of mechanisms that decide which promises are binding and which are not. Causa and laeso enormis served this particular purpose in the continental European private law systems before the great codifications. They were eliminated in the codification process, or immediately after that, because of their uselessness in a system that put so much emphasis on the absolute bindingness of contracts. It would however have been fruitful to have these concepts available in a later period of time, when contract law had to find a mechanism for deciding which contracts have to be binding upon the parties and which are not. But in most European legal systems, courts were not able to refer to these concepts anymore: they now had to use other legal concepts(good faith, the reliance principle in contract law and so on)to reach the desired result. It was only in the common law that the requirement of consideration still could play the role of distinguishing between promises that were enforceable and those that were not -although even here this role has become diluted The coming into being of a common European market may very well be a new evolutionary crisis in the evolutionary sense. It is highly likely that-again-legal institutions will receive a different content while keeping their identity in a process of adaptationism. The new environment that is now emerging at high pace is the European environment of a common market, in contrast to the national environment of a national market that most of the rules have adapted themselves to Joerges rightly points out that market integration leads to a rationalisation process in which all national law that constitutes an obstacle to the functioning of the internal market is under a pressure to change. This calls for a survey of which areas of private law will be most affected by this process 5.3 Path Dependence and Areas of European Private Law It is usually held that the process of emergence of a common market only calls for the unification of those parts of the law that are vital to that market, namely contract law and parts of the law of property(in particular security interests). From the evolutionary perspective that is chosen in this paper, we should however not be concerned with which parts are to be unified from a normative perspective, but-more descriptively- which parts are most likely to be affected by the changing environment To decide to what extent uniformity of private law can come about in Europe, it is at first useful to follow roe67 in his concept of -what he calls-weak-form path dependence. This type of path dependence only explains what has survived; it does not entail that the survivor is better than another: a society chose between two institutions and the choice became embedded, but the On this. see JAMES GORDLEY THE PHILOSOPHICAL FOUNDATIONS OF MODERN CONTRACT DOCtrine (1991) e Christian Joerges, The Europeanisation of Private Law as a Rationalisation Process and as a Contest C. Antonio Gambaro, Perspectives on the Codification of the Law of Property: An Overview, 5 ERPL 497(1997); Andrea Bonomi, La necessite d harmonisation du droit des garanties reelles mobilieres dans le marche umique europeen, in L'EUROPEANISATION DU DROIT PRIVE 497(F. Werro, ed, 1998) I leave aside the view of Richard Epstein, A Taste for Privacy? Evolution and the Emergence of a Naturalistic Ethic, 9 J. LEGAL STUD. 665(1980), who defends the socio-biological thesis that those who follow rules of conduct have a better chance of surviving than others who do not Roe, supra note 48, at 64610 A good example of this phenomenon is the elimination of mechanisms that decide which promises are binding and which are not. Causa and laesio enormis served this particular purpose in the continental European private law systems before the great codifications.63 They were eliminated in the codification process, or immediately after that, because of their uselessness in a system that put so much emphasis on the absolute bindingness of contracts. It would however have been fruitful to have these concepts available in a later period of time, when contract law had to find a mechanism for deciding which contracts have to be binding upon the parties and which are not. But in most European legal systems, courts were not able to refer to these concepts anymore: they now had to use other legal concepts (good faith, the reliance principle in contract law and so on) to reach the desired result. It was only in the common law that the requirement of consideration still could play the role of distinguishing between promises that were enforceable and those that were not – although even here this role has become diluted. The coming into being of a common European market may very well be a new evolutionary crisis in the evolutionary sense. It is highly likely that – again – legal institutions will receive a different content while keeping their identity in a process of adaptationism. The new environment that is now emerging at high pace is the European environment of a common market, in contrast to the national environment of a national market that most of the rules have adapted themselves to. Joerges rightly points out that market integration leads to a rationalisation process in which all national law that constitutes an obstacle to the functioning of the internal market is under a pressure to change.64 This calls for a survey of which areas of private law will be most affected by this process. 5.3 Path Dependence and Areas of European Private Law It is usually held that the process of emergence of a common market only calls for the unification of those parts of the law that are vital to that market, namely contract law and parts of the law of property (in particular security interests).65 From the evolutionary perspective that is chosen in this paper, we should however not be concerned with which parts are to be unified from a normative perspective, but – more descriptively – which parts are most likely to be affected by the changing environment.66 To decide to what extent uniformity of private law can come about in Europe, it is at first useful to follow Roe67 in his concept of – what he calls – weak-form path dependence. This type of path dependence only explains what has survived; it does not entail that the survivor is better than another: “a society chose between two institutions and the choice became embedded, but the 63 On this, see JAMES GORDLEY, THE PHILOSOPHICAL FOUNDATIONS OF MODERN CONTRACT DOCTRINE (1991). 64 Christian Joerges, The Europeanisation of Private Law as a Rationalisation Process and as a Contest of Disciplines, 3 EUROPEAN REVIEW OF PRIVATE LAW [E.R.P.L.] 179 (1995). 65 Cf. Antonio Gambaro, Perspectives on the Codification of the Law of Property: An Overview, 5 ERPL 497 (1997); Andrea Bonomi, La nécessité d’harmonisation du droit des garanties réelles mobilières dans le marché unique européen, in L’EUROPÉANISATION DU DROIT PRIVÉ 497 (F. Werro, ed., 1998). 66 I leave aside the view of Richard Epstein, A Taste for Privacy? Evolution and the Emergence of a Naturalistic Ethic, 9 J. LEGAL STUD. 665 (1980), who defends the socio-biological thesis that those who follow rules of conduct have a better chance of surviving than others who do not. 67 Roe, supra note 48, at 646