scholarly journals When the Actual World Is Not Even Possible

2020 ◽  
pp. 233-254
Author(s):  
Christian Wüthrich
Keyword(s):  
Quantum Gravity ◽  
Actual World ◽  
Possible Worlds ◽  
Fundamental Theory ◽  
Fundamental Level ◽  
Fundamental Structure ◽  
Space And Time ◽  
Mere Existence ◽  
Spatiotemporal Relations

Approaches to quantum gravity often involve the disappearance of space and time at the fundamental level. The metaphysical consequences of this disappearance are profound, as is illustrated with David Lewis’s analysis of modality. As Lewis’s possible worlds are unified by the spatiotemporal relations among their parts, the non-fundamentality of spacetime—if borne out—suggests a serious problem for his analysis: his pluriverse, for all its ontological abundance, does not contain our world. Although the mere existence—as opposed to the fundamentality—of spacetime must be recovered from the fundamental structure in order to guarantee the empirical coherence of the non-spatiotemporal fundamental theory, it does not suffice to salvage Lewis’s theory of modality from the charge of rendering our actual world impossible.

scholarly journals Thinking about Spacetime

2021 ◽  
pp. 129-153
Author(s):  
David Yates
Keyword(s):  
Quantum Gravity ◽  
Philosophy Of Mind ◽  
Fundamental Theory ◽  
True Nature ◽  
Fundamental Ontology ◽  
Fundamental Structure ◽  
Space And Time ◽  
Spacetime Structure ◽  
Research Programmes ◽  
Emergent Spacetime

Several different quantum gravity research programmes suggest, for various reasons, that spacetime is not part of the fundamental ontology of physics. This gives rise to the problem of empirical coherence, which I frame in terms of entailment: how could a non-spatiotemporal fundamental theory entail spatiotemporal evidence propositions? Solutions to this puzzle can be classified as realist or antirealist, depending on whether or not they posit a non-fundamental spacetime structure grounded in or caused by the fundamental structure. These approaches place different constraints on our everyday concepts of space and time. Applying lessons from the philosophy of mind, I argue that only realism is both conceptually plausible and suitable for addressing the problem at hand. I suggest a role-functionalist version of realism, which is consistent with both grounding and causation, and according to which our everyday concepts reveal something of the true nature of emergent spacetime.

Possible worlds

2018 ◽  
Author(s):  
Joseph Melia
Keyword(s):  
Modal Logic ◽  
Actual World ◽  
Possible Worlds ◽  
Abstract Objects ◽  
Causal Powers ◽  
Possible World ◽  
Space And Time ◽  
Wide Range ◽  
Concrete Objects

The concept of Possible worlds arises most naturally in the study of possibility and necessity. It is relatively uncontroversial that grass might have been red, or (to put the point another way) that there is a possible world in which grass is red. Though we do not normally take such talk of possible worlds literally, doing so has a surprisingly large number of benefits. Possible worlds enable us to analyse and help us understand a wide range of problematic and difficult concepts. Modality and modal logic, counterfactuals, propositions and properties are just some of the concepts illuminated by possible worlds. Yet, for all this, possible worlds may raise more problems than they solve. What kinds of things are possible worlds? Are they merely our creations or do they exist independently of us? Are they concrete objects, like the actual world, containing flesh and blood people living in alternative realities, or are they abstract objects, like numbers, unlocated in space and time and with no causal powers? Indeed, since possible worlds are not the kind of thing we can ever visit, how could we even know that such things exist? These are but some of the difficult questions which must be faced by anyone who wishes to use possible worlds.

Introduction

2021 ◽  
pp. 1-15
Author(s):  
Christian Wüthrich ◽  
Baptiste Le Bihan ◽  
Nick Huggett
Keyword(s):  
Quantum Gravity ◽  
Philosophical Work ◽  
Material World ◽  
Fundamental Structure ◽  
The Third ◽  
Space And Time ◽  
Methodological Challenges ◽  
Fertile Ground

Quantum gravity offers a fertile ground for philosophical work, particularly through its suggestion that spacetime may not be fundamental but merely a derivative structure. As such, theories of quantum gravity stand in a long tradition of physical theories with deep implications for the nature of space and time, and indeed the fundamental structure of our material world. This Introduction summarizes the contributions to this collection by structuring them around three themes. The first group of chapters analyses various aspects of the search of lost spacetime in quantum gravity. The second group studies metaphysical and epistemological aspects of the emergence in play in quantum gravity. The third group widens the investigations to several key methodological challenges arising in the context of quantum gravity.

The World Essence

Dialogue ◽  
1990 ◽  
Vol 29 (2) ◽  
pp. 205-218 ◽  
Author(s):  
John Bigelow
Keyword(s):  
Natural Kind ◽  
Actual World ◽  
Possible Worlds ◽  
Natural Kinds ◽  
Laws Of Nature ◽  
Joint Paper ◽  
Essential Properties ◽  
The World ◽  
Natural Necessity

Recently, Brian Ellis came up with a neat and novel idea about laws of nature, which at first I misunderstood. Then I participated, with Brian Ellis and Caroline Lierse, in writing a joint paper, “The World as One of a Kind: Natural Necessity and Laws of Nature” (Ellis, Bigelow and Lierse, forthcoming). In this paper, the Ellis idea was formulated in a different way from that in which I had originally interpreted it. Little weight was placed on possible worlds or individual essences. Much weight rested on natural kinds. I thought Ellis to be suggesting that laws of nature attribute essential properties to one grand individual, The World. In fact, Ellis is hostile towards individual essences for any individuals at all, including The World. He is comfortable only with essential properties of kinds, rather than individuals. The Ellis conjecture was that laws of nature attribute essential properties to the natural kind of which the actual world is one (and presumably the only) member.

The Actual World

2015 ◽  
pp. 64-85
Author(s):  
Donald Rutherford
Keyword(s):  
Actual World ◽  
Possible Worlds ◽  
The World

This chapter discusses Gottfried Wilhelm Leibniz’s theory of the actual world as the best of all possible worlds. The chapter opens with Leibniz’s response to the two most basic questions of metaphysics: Why is there something rather than nothing? And, why do certain things exist while other equally possible things do not? It examines Leibniz’s critique of Baruch Spinoza’s metaphysics, with particular reference to the argument that God must make a choice among possible worlds because not all possibles are “compossible.” In addition, it explores Leibniz’s claim that the best of all possible worlds is the world containing the highest level of perfection or reality, intelligibility, order, and harmony. The chapter concludes by looking at three theological doctrines underlying Leibniz’s conception of the best of all possible worlds: divine creation, conservation, and concurrence.

Analysing Modality

2020 ◽  
pp. 22-73
Author(s):  
Alastair Wilson
Keyword(s):  
Actual World ◽  
Possible Worlds ◽  
Modal Realism ◽  
Possible World ◽  
Metaphysical Modality ◽  
Novel Theory ◽  
Reductive Theory

This chapter presents and defends the basic tenets of quantum modal realism. The first of these principles, Individualism, states that Everett worlds are metaphysically possible worlds. The converse of this principle, Generality, states that metaphysically possible worlds are Everett worlds. Combining Individualism and Generality yields Alignment, a conjecture about the nature of possible worlds that is closely analogous to Lewisian modal realism. Like Lewisian modal realism, Alignment entails that each possible world is a real concrete individual of the same basic kind as the actual world. These similarities render EQM suitable for grounding a novel theory of the nature of metaphysical modality with some unique properties. Also like Lewisian modal realism, quantum modal realism is a reductive theory: it accounts for modality in fundamentally non-modal terms. But quantum modal realism also has unique epistemological advantages over Lewisian modal realism and other extant realist approaches to modality.

Epilogue

2016 ◽  
pp. 113-116
Author(s):  
Maria Rosa Antognazza
Keyword(s):  
Actual World ◽  
Possible Worlds ◽  
Theoretical Understanding ◽  
The Core ◽  
Practical Project ◽  
Scientific Advancement ◽  
Way Of Thinking ◽  
The Mind ◽  
Good And Evil

The ‘Epilogue’ concludes that it is possible to trace important elements of Leibniz’s way of thinking back to many different traditions, all of them reshaped and remodelled with the help of conversations with many hundreds of individuals, into a strikingly original outlook. It was in order to explain the actual world as we experience it, and what good and evil we find in it, that Leibniz took us on a journey through possible worlds and the mind of God. This theoretical understanding was for him at the core of an ultimately practical project of scientific advancement for the benefit of humankind.

scholarly journals A NEW SPIN ON QUANTUM GRAVITY

2008 ◽  
Vol 17 (03n04) ◽  
pp. 567-570 ◽  
Author(s):  
MARK G. JACKSON ◽  
CRAIG J. HOGAN
Keyword(s):  
Quantum Gravity ◽  
Cosmological Constant ◽  
Laboratory Tests ◽  
Space Time ◽  
Quantum Spin ◽  
Inherent Property ◽  
Fundamental Level ◽  
Bose Statistics ◽  
Gravitational Entropy

We suggest that the (small but nonvanishing) cosmological constant, and the holographic properties of gravitational entropy, may both reflect unconventional quantum spin statistics at a fundamental level. This conjecture is motivated by the nonlocality of quantum gravity and the fact that spin is an inherent property of space–time. As an illustration we consider the "quon" model, which interpolates between Fermi and Bose statistics, and show that this can naturally lead to an arbitrarily small cosmological constant. In addition to laboratory tests, we briefly discuss the possible observable imprint on cosmological fluctuations from inflation.

The Nature of Possibility

1986 ◽  
Vol 16 (4) ◽  
pp. 575-594 ◽  
Author(s):  
D.M. Armstrong
Keyword(s):  
Simple Form ◽  
Combinatorial Theory ◽  
Logical Space ◽  
Space And Time ◽  
The World ◽  
Mere Existence

I want to defend a Combinatorialtheory of possibility. Such a view traces the very idea of possibility to the idea of the combinations – all the combinations which respect a certain simple form – of given, actual, elements. Combination is to be understood widely enough to cover the notions of expansion and contraction. (My central metaphysical hypothesis is that all there is is the world of space and time. It is this world which is to supply the actual elements for the totality of combinations. So what is proposed is a Naturalistic form of a combinatorial theory.)The combinatorial idea is not new, of course. Wittgenstein gave a classical exposition of it in the Tractatus. Perhaps its charter is 3.4: ‘A proposition determines a place in logical space. The existence of this logical place is guaranteed by the mere existence of the constituents’ (my italics). There is a small additional combinatorial literature. I myself was converted to a combinatorial view by Brian Skyrms’ brief but fascinating article ‘Tractarian Nominalism.’

Modern Mathematics in Germany

1936 ◽  
Vol 29 (8) ◽  
pp. 390-393
Author(s):  
W. Threlfall
Keyword(s):  
Scientific Knowledge ◽  
Golden Age ◽  
Possible Worlds ◽  
The Other ◽  
Space And Time ◽  
The World ◽  
Modern Mathematics ◽  
Mathematics And Physics

Since I am speaking to you about modern German mathematics, I wish to call your attention to a most important subject, namely to the world which surrounds us, and to our scientific knowledge of its extent in space and time. There can be no doubt about the fact that this world we are living in is not the best of all possible worlds. Financial, industrial, and political dieases, you know them just as well on the other side of the great pond as we do on this side. Nevertheless in one respect we are living just now in a golden age. The world of science is in an excellent state and few eras have seen as important successes of mathematics and physics as ours.

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