Causation and the Objectification of Agency

This dissertation defends the so-called 'agency-approach' to causation, which attempts to ground the causal relation in the cause's role of being a means to bring about its effect. The defence is confined to a conceptual interpretation of this theory, pertaining to the concept of causation as it appears in a causal judgement. However, causal judgements are not seen as limited to specific domains, and they are not exclusively attributed to human agents alone. As a methodological framework to describe the different perspectives of causal judgments, a method taken from the philosophy of information is made use of – the so-called 'method of abstraction'. According to this method, levels of abstraction are devised for the subjective perspective of the acting agent, for the agent as observer during the observation of other agents’ actions, and for the agent that judges efficient causation. As a further piece of propaedeutic work, a class of similar (yet not agency-centred) approaches to causation is considered, and their modelling paradigms – Bayesian networks and interventions objectively construed – will be criticised. The dissertation then proceeds to the defence of the agency-approach, the first part of which is a defence against the objection of conceptual circularity, which holds that agency analyses causation in causal terms. While the circularity-objection is rebutted, I rely at that stage on a set of subjective concepts, i.e. concepts that are eligible to the description of the agent’s own experience while performing actions. In order to give a further, positive corroboration of the agency-approach, an investigation into the natural origins and constraints of the concept of agency is made in the central chapter six of the dissertation. The thermodynamic account developed in that part affords a third-person perspective on actions, which has as its core element a cybernetic feedback cycle. At that point, the stage is set to analyse the relation between the first- and the third-person perspectives on actions previously assumed. A dual-aspect interpretation of the cybernetic-thermodynamic picture developed in chapter six will be directly applied to the levels of abstraction proposed earlier. The level of abstraction that underpins judgments of efficient causation, the kind of causation seemingly devoid of agency, will appear as a derived scheme produced by and dependent on the concept of agency. This account of efficient causation, the ‘objectification of agency’, affords the rebuttal of a second objection against the agency-approach, which claims that the approach is inappropriately anthropomorphic. The dissertation concludes with an account of single-case, or token level, causation, and with an examination of the impact of the causal concept on the validity of causal models

Arquitectura multiagente para E/S de alto rendimiento en clusters

La E/S constituye en la actualidad uno de los principales cuellos de botella de los sistemas distribuidos de propósito general, debido al desequilibrio existente entre el tiempo de cómputo y de E/S. Una de las soluciones propuestas para este problema ha sido el uso de la E/S paralela. En esta área, se han originado un gran número de bibliotecas de E/S paralela y sistemas de ficheros paralelos. Este tipo de sistemas adolecen de algunos defectos y carencias. Muchos de ellos están concebidos para máquinas paralelas y no se integran adecuadamente en entornos distribuidos y clusters. El uso intensivo de clusters de estaciones de trabajo durante estos últimos años hace que este tipo de sistemas no sean adecuados en el escenario de computación actual. Otros sistemas, que se adaptan a este tipo de entornos, no incluyen capacidades de reconfiguración dinámica, por lo que tienen una funcionalidad limitada. Por último, la mayoría de los sistemas de E/S que utilizan diferentes optimizaciones de E/S, no ofrecen flexibilidad a las aplicaciones para hacer uso de las mismas, intentando ocultar al usuario este tipo de técnicas. No obstante, a fin de optimizar las operaciones de E/S, es importante que las aplicaciones sean capaces de describir sus patrones de acceso, interactuando con el sistema de E/S. En otro ámbito, dentro del área de los sistemas distribuidos se encuentra el paradigma de agentes, que permite dotar a las aplicaciones de un conjunto de propiedades muy adecuadas para su adaptación a entornos complejos y dinámicos. Las características de este paradigma lo hacen a priori prometedor para abordar algunos de los problemas existentes en el campo de la E/S paralela. Esta tesis propone una solución a la problemática actual de E/S a través de tres líneas principales: (i) el uso de la teoría de agentes en sistemas de E/S de alto rendimiento, (ii) la definición de un formalismo que permita la reconfiguración dinámica de nodos de almacenamiento en un cluster y (iii) el uso de técnicas de optimización de E/S configurables y orientadas a las aplicaciones