Clarke, Chris. “The Histories Interpretation of Quantum Theory and the Problem of Human/Divine Action."

The overall aim of Chris Clarke’s essay is to show how a modification of the consistent- histories interpretation of quantum mechanics provides a natural setting for understanding human and divine action. For Clarke, religion is largely about finding the meaning of the “good life,” and our aim is to help people live it. Hence we tell stories about the world we live in, some deriving from science, others from the great myths of religion. Weaving them together is important even though no part of the story represents a reality independent of ourselves and not all parts are equally supported by experiment. Clarke draws upon the phenomenology of Heidegger and Merleau-Ponty to argue that objective reality is located in the “second-person relationship” that lies between subject and object. Quantum theory plays an essential role in Clarke’s understanding of “the interplay of self, society, and Other” through which the concreteness of the world emerges.

Clarke then turns to the central problem of quantum mechanics: if it is a generalization of, and not an alternative to, classical mechanics, should we not use it to describe all of physics in a unified way? Yet if we do so, the theory predicts that macroscopic phenomena will be superpositions of states “flagrantly at variance with our experience,” as the Schrödinger’s cat experiment vividly depicts. Bohr and Von Neumann avoided this problem by dividing the world into the quantum system and its classical environment, and they characterized these realms by two separate time developments. But Clarke’s goal is an overall picture of the world that places the observer and the observed system on the same footing. To do so, Clarke focuses on the consistent-histories approach in which state reduction is unnecessary and only appearances are definite.

A “histories” approach links a sequence of preparation and measurement pairs such that each measurement becomes the preparation for the next. A “consistent” histories approach tries to rule out superpositions of macroscopically distinguishable states by considering only those histories whose probabilities obey classical logic. The approach was introduced by Robert Griffiths in 1984 and then extended to cosmology by Murray Gell-Mann and James Hartle, but problems were soon raised by Dowker and Kent. Clarke’s hope is to reformulate the approach to avoid these problems and then relate it to human and divine agency. To do so, he focuses on how we might restrict the possibilities of future histories given a fixed and acceptable history up to the present, looking at unmodified dynamics within sets of histories. This leads Clarke to propose a specific definition of consistency in terms of logical exclusivity and the rules of quantum mechanics, the physical significance of which arises through decoherence. As it turns out, although all classically acceptable histories are consistent, not all consistent histories are acceptable; additional structure is needed to single out acceptable histories. According to Clarke, the past history from which the future is predicted can help provide such a structure. This approach does not divide the world into classical and quantum domains, nor does it involve the collapse of the wavefunction. Moreover, in this approach, the history of the world, as both contingent and governed by decoherence, accounts for why the universe will continue to be classical.

Clarke then turns to the issue of human agency and, by analogy, divine action. According to Mae-Wan Ho, living organisms exhibit coherence, maintaining phase relations between the quantum states of their constituents over considerable distances and times. If so, our experience might not obey classical logic, and the nonBoolean aspects of an organism’s own history may be observationally detectable by an external observer. Quantum mechanics thus opens the possibility that we can share histories, at least momentarily. This provides Clarke with a way to engage the “other minds” problem. Drawing on Heidegger and Levinas he discusses the objective world in terms of the interrelation of beings-in-the-world. The “co-creation of the universe” then arises through the set of such intermeshing histories. The consistent-histories approach also allows us to move beyond the “determinism vs. random” debates about free will. Instead, decision-making involves a shift from one consistent Boolean logic to another. We experience this as creativity, though the shift appears random to others. Our free will is thus characterized by the simultaneous creation of volition and a framework of meaning which justifies this volition.

Clarke describes his experience of the divine as of a guidance that is immanent in the concrete flow of events and yet transcendent, not contained in any horizon. He uses the idea of “entrainment” in quantum theory, where previous events are realized in the present, to describe divine action as top-down entrainment, coordinating and informing the individual acts of will that it contains, rather than as a divine influence at the atomic level. This concept of divinity goes beyond pantheism, but coheres with panentheism and with a view of divinity embodied in the world as suggested by the second mahavakya of the Upanishads.

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