Changes of the Scientific Paradigm in String Theory

The project will analyse the philosophical implications of string theory. It shall discuss to what extent characteristics of string physics are at variance with aspects of the classic conceptions of science and can offer new perspectives on conceptual questions in philosophy of science. String theory holds a highly influential position in particle physics and parts of cosmology despite its theoretically incomplete and empirically unconfirmed status. It shall be analysed in how far this situation can be understood in terms of specific shifts of the scientific paradigm which go along with the recent evolution of elementary particle physics. The question shall be discussed by comparing the case of string theory with a fundamental physical theory that lies closer to `scientific orthodoxy` (loop-quantum-gravity) and with a position in philosophy of science (Nancy Cartwright`s) that rejects the fundamentalism that serves as a guideline of the particle physics research program. Potential philosophical implications of string physics shall be addressed by discussing the question of limitations to the underdetermination of scientific theory building by the available empirical data and by analysing string theory`s possible affinities with the philosophical position of structural realism. While the main emphasis of the project will be on string physics itself, it will be important to understand and specify the continuities which connect the string theoretical case with empirically confirmed theories in particle physics.

The project aimed at analysing the mechanisms of theory assessment in contemporary high energy physics. The focus of the investigation was laid on string theory. New conceptions in particle physics and string physics are developed in an unusual context. On the one hand, their empirical predictions - if they can be specified at all - often lie far beyond the reach of today`s experimental methods. Theories therefore are often developed for several decades without substantial empirical confirmation. On the other hand, however, the evolution of those theories often shows a consistent directedness over decades and leads to a high level of trust in the theory`s validity despite the lack of empirical confirmation. String theory is the most conspicuous example in this respect. Trust in the theory is based on theoretical assessments which take into consideration the characteristics of theory dynamics as well as the theory`s conceptual characteristics. Project research was concerned with an analysis of this strategy of theory assessment. The idea was formulated that the process of theory assessment in contemporary high energy physics constitutes a paradigmatic shift where theoretical methods of theory assessment acquire a significance that had seemed unacceptable at earlier stages of physics. One symptom of this paradigmatic chance is the fundamental and often remarkably sharp disagreement between critics and exponents of string theory with regard to the theory`s status. Supporters of the old paradigm argue against exponents of the new paradigm of theory assessment in this case. The Principle of the assessment of underdetermination of scientific theory building was introduced as the basis of the new strategies of theory assessment. All essential elements of the new kind of theory assessment were argued to be reducible to that principle. If a scientist comes to the conclusion that the underdetermination of scientific theory building is strongly limited in a given context, this provides the basis for taking the theory to be probably viable. A number of scientific contexts other than string physics were discussed where the question of underdetermination plays a significantly more important role than it had been acknowledged.