09 April // Prof. Dr Ulrich Gähde (Hamburg): What are thought experiments?

Thought experiments have often played a central role, especially in times of scientific crises and revolutions. For example, they flourished at the beginning of modern physics or in the formative phases of the special and general theory of relativity and quantum mechanics. Thought experiments have also been frequently used as intellectual tools in philosophy since ancient times. However, despite numerous attempts at clarification, the term "thought experiment" has remained colourful and ambiguous to this day. The lecture will attempt to provide an initial answer to the question of what characterises thought experiments and explain them using several classical examples. Particular emphasis will be placed on the similarities between philosophical and scientific thought experiments.

16 April // Dr Ulrich Kühne (Berlin): Stroke of genius or lazy magic? Critical remarks on the use of thought experiments as a scientific method

On the one hand, the history of science contains fantastic examples of discoveries of natural laws that seem to have been revealed by the mere reflection of pure reason. On the other hand, we know that in the natural sciences, nature can always provide surprises and has already disproved many seemingly reasonable speculations. The lecture will be a plea for critical thinking and a warning against false certainties. Used sensibly, however, thought experiments can even help to expose the prejudices in our thinking and support the search for empirically based theories.

23 April //Dr Werner Eisner (Hanover): Thought experiments in the history of quantum mechanics

In this lecture, the significance of the thought experiment for the development of quantum theory and the subsequent debate with critics (such as Einstein) will be analysed. Famous cases ("Schrödinger's cat", the "Heisenberg microscope", the "EPR experiment") will be discussed, partly on the basis of excerpts from the original sources, but also lesser-known considerations that can be found, for example, in the correspondence of physicists in the development phase of quantum theory. Many of these thought experiments are still a source of heated debate and numerous misunderstandings that need to be addressed, especially as some of these experiments can be technically realised today.

30 April // Prof. Dr Manfred Stöckler (Bremen): The paradox of Einstein, Podolsky and Rosen - On the fate of a former thought experiment

The thought experiment published in 1935, which became famous under the name "EPR paradox", allows a deep insight into the basic structure of the then newly developed quantum theory without any special knowledge of mathematics. In particular, it emphasises its non-local properties, which have led to all kinds of speculation about "spooky remote effects" and the limits of the classical atomistic view of the world. A closer look at the history of the EPR paradox shows that very different conclusions have been drawn from it depending on the background knowledge. What does this mean for the role of thought experiments in physics? What changed when the proposed experiment could be realised? How do different theories about thought experiments prove themselves in this case study? And what can we learn from the EPR paradox about quantum theory and the microworld from today's perspective?

07 May // Prof. Dr Alexander Hartmann (Oldenburg): Computer simulations: Thought experiments for the lazy?

The historical development of computer programming can be seen as a form of thought experiment. Algorithms were developed long before computers existed. Therefore, their "execution", e.g. to find prime numbers (Eratosthenes) or to calculate the number Pi (Archimedes), was often limited to thought experiments. With the development of powerful computers, not only could such "classical" algorithms be carried out, but the new research branch of computer simulations developed. Here, natural processes are reduced to the simplest possible basic principles, which is also essential for thought experiments (or theorising in general). On the other hand, computer simulations can be used to realise and run through very complex model systems. The implications of the initially mental rules, i.e. the behaviour of the model systems, could never be investigated in pure thought experiments. Are computer simulations therefore thought experiments for lazy (or clever) people?

14 May // Prof. Dr Falk Rieß (Oldenburg): Thought experiments in physics lessons

Criticism of (real) physics lessons focuses on the lack of interest and motivation that the lessons trigger, on the unsatisfactory learning outcomes that they achieve and on the inaccurate picture of the workings and systematics of science (Nature of Science) that is conveyed - often not consciously. The proposal to use thought experiments as a pedagogical tool goes back to Ernst Mach. Since then, there have been a number of proposals to include "classical" thought experiments in physics lessons (Galileo, Einstein, Franklin). It is always emphasised that these case studies must be embedded in a "narrative context" in order to be didactically effective. I will argue in favour of an imaginative combination of thought experiment and real-life experiment, which should represent the unity of mental and physical work in the process of scientific knowledge.

28 May // Prof. Dr Michael Stöltzner (Columbia / South Carolina): The Laboratory of Best Possible Worlds - Principles of Variation and Related Thought Experiments in Mathematical Physics

Hardly any other principle of theoretical physics has given rise to more philosophical controversy than the principle of least action and the associated extremal principles. This is not only due to its origin in the midst of a fiercely fought dispute over priorities in the middle of the 18th century, but also to its form. It compares the dynamics of a physical system with possible alternatives, whereby the actual dynamics are characterised in most, but not all, cases by the minimum of an integral expression. This comparison of possible worlds has repeatedly associated the principle with the idea of a sparsely governing nature or a teleology of nature. In the lecture, however, it will be analysed as a thought experiment on the applicability of mathematics, which allows the different levels of argumentation of this principle to be separated more clearly.

04 June // Prof. Dr Julian Reiss (Rotterdam): Thought experiments in economics: certainty and applicability

Thought experiments play an important role in many empirical sciences. Theorists of science even go so far as to claim that they have a central function in times of revolutionary theory change. The aim of this lecture is to clarify the relevance and justifiability of the method of the thought experiment in the field of economics. Understood as experiments carried out on hypothetical modelling systems, thought experiments are extremely numerous in economics and are mainly used for scientific explanatory purposes as well as for causal induction. Here I will describe these roles in more detail and determine whether and under what conditions thought experiments can adequately fulfil them.

11 June // Prof. Dr Daniel Cohnitz (Tartu): Can we trust thought experiments in philosophy? [different location: A05 0-056]

Thought experiments have been increasingly criticised in philosophy, especially in the last three decades. This discussion has then expanded into a general debate on methods in recent years. Such debates are generally fruitless in philosophy if they are understood as "metaphilosophy". Even a metaphilosophy seems to have to make epistemological and metaphysical presuppositions that are themselves philosophically controversial. However, this makes a metaphilosophy unusable as a neutral system within which philosophy can be practised. Is it therefore not possible to answer in general terms whether thought experiments can be trusted in philosophy?

18 June // Prof. Dr. Dagmar Borchers (Bremen): How to save world-famous violinists from death and stop runaway steamrollers - thought experiments and scenarios of moral dilemmas in ethics

There are many thought experiments in ethics, some of which are bizarre, but some of which are also really funny and original. But what exactly is their function? Generally speaking, the authors are interested in presenting their own intuitions and then evaluating and commenting on them in the context of the respective argument. But how we react to a thought experiment depends largely on how it was conceived and in what order we are confronted with different scenarios. So what do you gain from a thought experiment for an argument in ethics? In this context, we will also have to talk about the significance of intuitions for ethical argumentation - and this is controversial territory.

25 June // Prof. Dr Thomas Grundmann (Cologne): Has the armchair had its day? On the socio-psychological frontal attack on philosophical intuitions

Intuitions about hypothetical cases play a decisive role in philosophical thought experiments (Gettier cases, Twin Earth scenarios, Searle's Chinese Room). The almost naïve assumption that there is a stable intersubjective agreement here has been massively shaken in the last ten years by studies of so-called "experimental philosophy". Social psychological studies show that our intuitions about philosophical cases fluctuate extremely and are influenced by a number of extraneous factors (cultural or socio-economic background, affects, position and anchor effects). Some philosophers have drawn the conclusion that thought experiments based on intuitions have no epistemic value. The lecture will argue that and why this consequence is unfounded and unacceptable.

02 July // Prof. Dr Jörg H. Y. Fehige (Toronto): Thinking Thought Experiments. The current discussion about the thought experiment

Since the end of the 1980s, an intensive philosophical debate has been sparked around the thought experiment. At the centre of the lecture is the question: If the majority opinion is correct that thought experiments have played a prominent role in the formation of theories in the natural sciences and humanities, how should this role be qualified epistemologically? Accordingly, the most influential theories for explaining the cognitive effectiveness of thought experiments are presented and subjected to critical enquiry. In a concluding outlook, it will be suggested how the usefulness and success of thought experiments in the natural sciences and humanities could be explained with recourse to a naturalistic theory of intuitions.