Pragmatic Ontology Identifying Propensity as Substance

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Pragmatic OntologyIdentifying Propensity as
Substance

• Ian Thompson
• Physics Department, University of Surrey,
  Guildford.

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Views of Substance synopsis

• Aristotle
• matter in some form
• Descartes
• (essentially) extension
• Newton, Boyle
• corpuscles
• Leibniz
• whose nature requires its separate existence

• Locke
• real essence unknown
• Boscovich
• point centre of forces
• Whitehead, Russell
• only events

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Substance and Form

• Return to basic Aristotelian (physical) view
• Particular objects
• Exist, separately or in relation
• All composed of some substance in some form
• Form may be mathematical or qualitative.
• Substance (generic) to be determined
• called matter (hyle) by Aristotle.

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Form

• Examples
• shape, number, symmetry, function, field, wave,
  point, length, area, volume and amplitude
• also manner of aggregation of parts
• Pure forms without substance cannot exist,
• whether they be information, mathematics or
  functions
• the world may have triangular objects, but is not
  made of triangles (or wave functions)

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Dispositions

• Examples
• cause, propensity, power, capability,
  potentiality, energy (kinetic and potential),
  mass, charge, field coupling, force, pressure,
  momentum, impetus, elasticity or rigidity
• Propensities dispositions which manifest as
  probabilities
• Investigated in detail by the sciences
• Find explanations in terms of a few underlying
  dispositions structure of aggregation

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Dispositional Essentialism

• Necessary for Causation
• to answer what would happen, if ..
• Never explainable by non-dispositional
• So Dispositions are Essential to Nature
• See recently eg Molnar Powers (OUP)
• justification would require another talk
• Question now
• How are dispositions related to substance?

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Pragmatic Ontology

• Find what is sufficient for the dispositional
  causation of events
• interpret this realistically,
• postulate it to exist
• Try to find just what is necessary for a cause to
  give the effect.
• pragmatic, as existence inferred from effects. We
  find an effective ontology.

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Places where actions can occur

• Every thing is (at least) at the places (in space
  time) where it has a disposition to immediately
  act or interact
• pragmatic in the sense that there is no need for
  it to be anywhere else, since it can never have
  an effect there!
• Where and when both necessary to describe
  actions
• do not assume that everything is acting all the
  time (important for quantum physics)

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Substance

• The substance of a thing is defined as the set
  of propensities for how it can act.
• pragmatic, because there is nothing else needed
  to be given to specify an object, apart from when
  and where it is, and how it can act.
• The substance of an object is constituted by the
  set of underlying propensities for how it can act
  or interact (more specifically)

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Common Expressions

• Physicists often say
• electromagnetic force fields
• potential energy fields,
• matter is a form of energy.
• In each case,
• a dynamical property (force or energy) is being
  pragmatically identified as some kind of
  substance
• Is it possible to make philosophical sense of
  this?

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Fields

• The distribution of propensities over a region of
  space time is a field.
• this is the distributions form.
• Interactions from overlapping fields
• as both objects then act together
• Composite objects structure of many overlapping
  fields of its parts.

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Substance Form

• Propensity is the substance
• (Aristotle this is the matter, hyle)
• Field is the form
• Objects are substance in a form,
• ? fields of propensity.
• May be many kinds of propensity
• many specifications of how actions occur.
• e.g. mass, charge, masscharge, etc.

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Successive events

• We might well assume
• Between any pair of succeeding events in time of
  an object, other interactions are possible.
• We might also assume
• Such intermediate-in-time events are not
  necessary
• This distinguishes classical quantum

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Movable Substances

• Definition so far
• Substances endure over the time between
  successive events
• Generalise
• The same form (shifted in spacetime), the same
  propensities, before and after an event ?
  successive stages of the same substance (now
  movable)

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Quantum Substances?

• See whether these ideas help understand quantum
  physics (QM)
• Newtons corpuscles are inadequate
• those with definite extension, hardness,
  impenetrability, mobility, and inertia of parts
• Need to have some ideas about
• wave-particle duality, nonlocality, measurements,
  etc

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Fields of Propensities

• Not necessarily located in small fixed volumes of
  space
• no centre as the true substance
• only source is the previous event
• only localised very briefly at times just after
  this event
• most of the time they may have significant
  spatial extensions
• Like the wave packet of QM.

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Measurements are Actual Selections

• Actual measurements are selections of alternate
  histories
• Unphysical alternatives actually removed by some
  (undiscovered) dynamical process.
• This sets to zero any residual coherence between
  nearly-decoherent histories, if a branch
  disappears.
• Different alternatives in QM often summarised by
  an operator of which they are distinct
  eigenfunctions.

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Wave Equation?

• I suspect that the field distributions may be
  described by wave equations.
• but that is another talk
• If it were so
• obtain wave behaviour
• (diffraction, interference, etc).

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No hidden particles!

• There are no such things as small particles like
  corpuscles with definite properties.
• Nor are there such things as small particles with
  uncertain or indeterminate properties.
• Measurements are not the process of assigning
  values to properties of particles, even if we
  allow that they are peculiar particles in not
  having definite properties at all past times.
• Nor are measurements the momentary production of
  particles with definite properties for that
  moment.

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Particle Behaviour?

• Yes
• Propensity fields (wave packets) are unitary
  objects
• Definite shape at any time
• Interact by overlaps (eg field quanta)

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Wholeness Non-locality

• The propensity fields
• extend over finite space regions and time
  intervals, so are non-local,
• act to select just one actual alternative,
• subsequent propensity fields develop from the
  actual alternative selected,
• whole substances, but
• usually contain many virtual substances in
  whole unitary compound
• So express using configuration space, not in 3D.
• We need further analysis of quantum composition.

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Conclusions

• Pragmatic approach to Ontology
• what is necessary and sufficient for the
  dispositional causation of events is interpreted
  realistically, and postulated to exist.
• Substance identified by dispositions
• not just the bare subject for dispositions.
• Forms of objects are spacetime fields,
• Substances are fields of propensity

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References

• Website
• www.generativescience.org
• Dispositional Essentialism
• Alexander Bird, Toby Handfield, Steven Mumford,
  George Molnar,
• Ian Thompson BJPS, 39 (1988) 67-79
• and others from Aristotle on.
• Propensity Fields
• Nicholas Maxwell (UCL)

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Revisit Hamiltonian QM
Active Energy
Propensity Wave
Actual Outcome
(Hamiltonian Operator)
(Wave function)
(Measurement)
Borns Probability Rule
Schrödinger Equation

• Energy operator generates the wave function,
• according to Schrödingers time-dependent
  equation
• Propensity wave generates the actual measurement
• according to Borns Probability Rule for ?2
• Actual measurements selections of alternate
  histories
• Energy, propensity waves are 2 kinds of
  propensity.

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Measurements are Actual Selections

• Actual measurements are selections of alternate
  histories
• Unphysical alternatives actually removed by some
  (undiscovered) dynamical process.
• This sets to zero any residual coherence between
  nearly-decoherent histories, if a branch
  disappears.
• Different alternatives ui often summarised by an
  operator A of which they are distinct
  eigenfunctions Aui ?i ui, labeled by
  eigenvalues ?i .

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Nonlocal Hidden Variables in ordinary QM

• Energy, propensity and actual events are
  all present, though hidden, in a generative
  sequence.
• Energy and propensity exist simultaneously,
  continuously and non-locally.
• Actual events are intermittent.
• Does this describe QM as we know it?

General connection Continuous existence ?
determinism Intermittent existence ? indeterminism
(why?)
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Wholeness Non-locality

• The propensity fields
• extend over finite space regions and time
  intervals, so are non-local,
• act to select just one actual alternative,
• subsequent propensity fields develop from the
  actual alternative selected,
• whole substances, but
• usually contain many virtual substances (see
  later) in whole unitary compound
• So express using configuration space, not in 3D.
• We need further analysis of quantum composition.

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Multiple Generative Levels

• Description of ordinary quantum mechanics
  requires the idea of multiple generative levels
• General idea
• Multiple generative levels are a sequence A?B?C
  ? .. in which A generates or produces new
  forms of B using the present form of B as a
  precondition.
• Then B generates C in the same way,
• and so on until end when nothing is active.

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Multiple Generative Levels II Reality

• In the general case, Multilevel Propensities are
  parallel processes all equally real.
• Level B, for example, is not just an approximate
  description of successive forms of other levels A
  or C.
• Neither is B a microscopic constituent of either
  of levels A or C.
• Rather, levels A, B, C,... are real processes
  in parallel that interact with other by
  relations of generation and pre-condition.

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Principles, Causes and Effects

• The sequence energy ? propensity ? actual
  event, does not have the three levels playing
  homogeneous roles as in the general case A?B?C
• If we look in more detail, we see
• energy ? principle
• Conservation of energy via H governs the process
• propensity ? cause
• Time evolution and propagation of influence
• actual event ? effect
• The final result
• Pattern appears Principle ? Cause ? Effect

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Potentials from Virtual Particle Exchange

• Where does the Hamiltonian come from? We cannot
  just invent it!
• We know that the potential energy part of the
  Hamiltonian really comes from field-theoretic
  virtual processes. What are these events?
• Kinetic energy, also, has a mass which is
  dressed by virtual processes.
• Propose the Energy Operator is itself
  generated by (further) previous levels.

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Propensities for Virtual Processes

• Propose 2 linked sets each of three generative
  levels
• both with (broadly) corresponding processes,
• i.e. still in pattern Principle ? Cause ?
  Effect.
• Virtual processes (in some way) generate the
  terms of the Energy Operator (the Hamiltonian).

Field Lagrangian
Virtual Quantum Fields
Virtual Events
Energy Operator
Propensity Wave
Actual Events
Principle
Effect
Cause
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Virtual Principle ? Cause ? Effect

• The field-theoretic Lagrangian Variational
  Principle starts the generative sequence.
• Propagating field quanta (virtual quantum field
  substances),
• e.g. photons, gluons, quarks, leptons, ...
• derived from the Lagrangian by a Variational
  Principle.
• generate virtual events when interacting.
• Virtual events (of quantum field theory) are
  point events which generate the potential energy
  part of the Hamiltonian operator.
• They do not all actually occur because, for
  example, they may generate potentials that are
  never active in the selected sequence of actual
  outcomes.

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Virtual and Actual Events

• VIRTUAL EVENTS
• Point events
• (notpoint measurements)
• Interactions
• Microscopic interactions
• Continuous
• Deterministic (apparently)
• Contribute to alternate futures
• Have intrinsic group structure (e.g. gauge
  invariance, renormalisation)

• ACTUAL EVENTS
• Visible events in history
• (e.g. measurement)
• Selections
• Macroscopic decoherence
• Discrete
• Probabilistic
• Definitely occur (or not)
• Have branching tree structure

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Complications are all the stages needed?

• Some physicists try to derive probabilities of
  actual outcomes directly from field theory,
  without a Hamiltonian or potential. Is the idea
  of a potential only an approximation suitable for
  some energy scales?
• I would ask Are there not still some roles for
  mass, kinetic and potential energy, energy
  conservation?
• I agree that a Hamiltonian (etc) is a composite
  object, whose detail reflects its genesis

Natural things are more complicated, and more
beautiful, the more you look into them
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A BIGGER Picture?
Spacetime formation?
Some speculative ideas!
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Conclusions

• I hope that this is an accurate classification of
  the several stages in nature, as seen in QM.
• Should help to understand quantum physics and
  what really goes on.
• We can find what the wave function describes,
  if we think carefully and with imagination.
• More work needed to understand the mathematical
  substructures at each level,
• We should look for new physics (new theories and
  new experiments).