Paul M. Näger

The causal problem of entanglement

This paper expounds that besides the well-known spatio-temporal problem there is a causal problem of entanglement: even when one neglects spatio-temporal constraints, the peculiar statistics of EPR/B experiment is inconsistent with usual principles of causal explanation as stated by the theory of causal Bayes nets. The conflict amounts to a dilemma that either there are uncaused correlations (violating the causal Markov condition) or there are caused independences (violating the causal faithfulness condition). I argue that the central ideas of causal explanations can be saved if one accepts the latter horn and explains the unfaithful independences by a stable fine-tuning of the causal parameters.

Impact of Loop Statistics on the Thermodynamics of RNA Folding

Loops are abundant in native RNA structures and proliferate close to the unfolding transition. By including a statistical weight approximately l(-c) for loops of length l in the recursion relation for the partition function, we show that the heat capacity depends sensitively on the presence and value of the exponent c, even for a short explicit tRNA sequence. For long homo-RNA, we analytically calculate the critical temperature and critical exponents which exhibit a nonuniversal dependence on c.

Physical Composition by Bonding

Van Inwagen proposes that besides simples only living organisms exist as composite objects. This paper suggests expanding van Inwagen’s ontology by also accepting composite objects in the case that physical bonding occurs (plus some extra conditions). Such objects are not living organ-isms but rather physical bodies. They include (approximately) the complete realm of inanimate ordinary objects, like rocks and tables, as well as inanimate scientific objects, like atoms and mol-ecules, the latter filling the ontological gap between simples and organisms in van Inwagen’s origi-nal picture. We thus propose a compositional pluralism claiming that composition arises if and on-ly if bonding or life occurs.

Entanglement and Non-locality: EPR, Bell and Their Consequences

Entangled states are a specific feature of quantum physics that neither have a counterpart in classical physics nor in the realm of our ordinary experiences. In this chapter we outline the debate about these particular states both historically and systematically. We delineate how the debate originated in an argument for the incompleteness of quantum mechanics by Einstein, Podolsky and Rosen, and we show why, on the one hand, the argument is not considered convincing today, on the other hand, however, still affects present discussions. In a second part we give a systematic overview over the contemporary debate on entanglement which focusses on Bell’s theorem and its consequences. Discerning different levels, we reconstruct the theorem and its premises in a clear way and discuss possible consequences. We analyze in detail the received view that Bell’s theorem implies non-locality and relate it to concepts such as “non-separability” and “holism”. Especially we examine the question whether the phenomena involving entangled systems can be explained causally and whether the central conflict between a non-locality and the theory of relativity can be solved.

Causation, Constitution, and Existence

Contemporary debates about mechanisms in the philosophy of science raise the question about the relation between constitutive and causal relations. These discussions so far have not received Ernest Sosa’s “Varieties of Causation” (1980), which addresses similar questions from a metaphysical point of view. The present paper reconstructs and evaluates Sosa’s arguments from the perspective of the contemporary debates. We argue that while Sosa’s arguments are probably not suited to advance the current debate, his claim that there are different varieties of causation might be an interesting idea to consider for those who assume that there are interlevel causal relations.

Verschränkung und Nicht-Lokalität: EPR, Bell und die Folgen

Die Probleme, die wir in diesem Kapitel diskutieren, haben ihren formalen Ursprung in der Art und Weise, wie in der Quantentheorie zusammengesetzte Systeme beschrieben werden (vgl. Abschn. 3.1.2).