Les objectifs principaux de cette thèse sont expliquer l’émergence de nouvelles dynamiques concurrentielles caractérisées par une symbiose entre concurrence et pouvoir de marché et élucider comment elles peuvent être appréhendées sous l’angle de la théorie de la concurrence. Le chapitre I investigue l’évolution des formes de la concurrence aux États-Unis de 1840 jusqu’à nos jours. On montre qu’alors que dans certains cas le pouvoir de marché s’est traduit par l’entrave à la concurrence (et vice-versa), dans d’autres les deux établissent une relation symbiotique. Le chapitre II fait une revue des théories de la concurrence et conclut qu’elles ne rendent pas compte de la coexistence de deux faits stylisés majeurs propres à la forme de concurrence hégémonique actuelle : des différentiels de taux de profit de long terme et une forte concurrence par les prix.Le chapitre III développe une contribution à la théorie de la concurrence entre et au sein des chaînes globales de valeur (CGV). On montre que l’interdépendance inégale est la source du pouvoir de marché intra-CGV, ce qui explique les différentiels de taux de profit entre firmes appartenant à une même CGV. On montre par la suite comment ils peuvent être compatibles avec une forte concurrence par les prix. Le chapitre IV étudie le capitalisme de plateforme en se focalisant sur les « firmes de coordination algorithmique basées sur la confiance » (FCABC). En s’appuyant sur le cas de la firme de VTC Uber, on argumente que la FCABC conjugue du pouvoir de marché avec une forte concurrence par les prix dans une dynamique concurrentielle dans laquelle il y a une tendance à la monopolisation. / The main objectives of this thesis are to explain the emergence of competitive dynamics characterized by a symbiosis between competition and market power and to elucidate how they can be apprehended through the lenses of competition theory. Chapter I investigates the evolution of forms of competition in the United States from 1840 to today. We show that while in some cases market power has translated into hindering competition (and vice versa), in others the two establish a symbiotic relation. Chapter II reviews competition theories and concludes that they do not account for the coexistence of two major stylized facts characteristic of the current hegemonic form of competition: long-run profit rate differentials and strong price competition. Chapter III develops a contribution to competition theory within and between global value chains (GVC). We show that uneven interdependence is the source of intra-GVC market power, which explains long-run profit rate differentials between firms belonging to the same GVC. Then we show how they can be compatible with strong price competition. Chapter IV studies platform capitalism with a focus on “trust-based algorithmic coordination” (TBAC) firms. Building on the case of the ride-hailing firm Uber, we argue that the TBAC firm conjugates vertical market power with strong price competition in a competitive dynamics in which there is a tendency towards monopolization.

Copyright is conventionally justified as an incentive to produce and disseminate works of authorship. We can justify and theorise copyright more richly, not least because empirical evidence does not support the incentive narrative. Rather than focussing on quantitative matters such as the number of works incentivised and produced, we should consider copyright's qualitative influence on culture. A threshold objection to such an approach is the risk of cultural paternalism. This objection can be overcome. Rather than specifying paternalistic standards of merit for works, we can target the conditions under which their creation and consumption takes place. I argue, firstly, that we should adopt the following high-level principles: (i) that the conditions of creation and consumption of works should be conducive to democratic deliberation (democracy) and (ii) that they should facilitate the development of human capabilities (autonomy). Secondly, I propose that we pursue three mid-level objectives, which are helpful indicia of democracy and autonomy: - a fair and wide distribution of communicative and cultural power (inclusiveness); - diversity in the content and perspectives available to the public (diversity); and - conditions that permit authors and users of works to engage rigorously with the conventions of the media in which they operate (rigour). It is often said that copyright obstructs important qualitative objectives, like freedom of expression, and that we could better pursue these goals by weakening copyright and relying on non-proprietary alternatives. My approach produces a more optimistic, but also more complicated, view of copyright. While copyright's qualitative influence is not optimal, reductions in the strength and scope of copyright sometimes produces conditions and incentive structures that are worse for inclusiveness, diversity and rigour than stronger copyright. For example, both attention and wealth are highly concentrated in networked information economies driven by free sharing of content, and this is bad for diversity or inclusiveness. Online business models, based on surveillance of users' consumption of free works, are corrosive of autonomy and democracy. Merely removing copyright-based restrictions on the sharing of works is not a panacea for copyright's ills. A qualitative theory such as mine equips us to better understand and calibrate more richly the trade-offs involved in copyright policy decisions, and encourages us to treat copyright as part of a broader, qualitatively-oriented information and cultural policy.