Paivio Allan: IMAGERY AND VERBAL PROCESSES (Holt, Rinehart and Winston, 1971)
Paivio was the first to posit that the mind must use two different types of
representation, a verbal one and a visual one, corresponding to the brain's
two main perceptive systems.
Parfit Derek: REASONS AND PERSONS (Oxford Univ Press, 1985)
Parfit deals with matters of identity and consciousness. His famous thought
experiment asks what happens to a person who is destroyed by a scanner in
London and rebuilt cell by cell in New York by a replicator that has received
infinitely detailed information from the scanner about the state of each single
cell, including all of the person's memories.
Is the person still the same person? Or did the person die in London?
What makes a person such a person: bodily or psychologically continuity?
If a person's matter is replaced cell by cell with equivalent cells is the
person still the same person?
If a person's psychological state (memory, beliefs, emotions and everything)
is replaced with an equivalent psychological state is the
person still the same person?
The question eventually asks what is "a life": is it a continuum of bodily
states, whereby one grows from a child to an adult, or is it a continuum of
psychological states? Or both? Or none? Parfit thinks that psychological
continuity is what matters.
Parkin Alan: EXPLORATIONS IN COGNITIVE NEUROPSYCHOLOGY (Blackwell, 1996)
A survey of the field, from the split brain to connectionist models.
Pattee Howard Hunt: HIERARCHICAL THEORY (Brazillen, 1973)
Collects five essays. Herbet Simon's "The organization of complex systems"
proves that hierarchical organization is pervasive
Pattee's "The physical basis and origin of hierarchical control" proposes
general principles of organization and asks for a physical theory of the
origin of life that rely on such principles. One fundamental finding is that
hierarchical control does not reside in any one level of the hierarchy,
it operates between levels.
Pawlak Zdzislaw: ROUGH SETS (Kluwer Academic, 1991)
Rough sets are sets that are defined in terms of lower and upper bounds..
Rough sets are useful in classifying imprecise, uncertain or incomplete
knowledge.
The approximation space is a classification of the domain into disjoint
categories. The lower approximation is a description of the objects
that are known with certainty to belong to the domain.
The upper approximation is a description of the objects
that possibly belong to the domain.
Peacock Christopher: A STUDY OF CONCEPTS (MIT Press, 1992)
The book details Peacock's own theory of concepts.
Peak David & Frame Michael: CHAOS UNDER CONTROL (W.H.Freeman, 1994)
A textbook for beginners on complexity, with a good introduction to fractals.
Pearl Judea: HEURISTICS (Addison Wesley, 1984)
A well-organized and comprehensive technical textbook on heuristic methods for
problem solving: hill climbing, best first algorithms, and so forth. The second
part is an analysis of performance, the third part is devoted to game playing.
Pearce John: ANIMAL LEARNING AND COGNITION (Psychology Press, 1997)
A survey of a century of experiments on animals learning, memory and
communication.
Pearl Judea: PROBABILISTIC REASONING IN INTELLIGENT SYSTEMS (Morgan Kaufman, 1988)
A property of information is that it is relevant for some other type of
information. Relevance's dual property is dependence: if a piece of information
is relevant to another piece of information, than this piece of information
is dependent on the former. Relevance can be defined as "conditional
independence".
Pearl provides an axiomatic formulation of "conditional independence".
Pearl's causal networks (conditional dependency's graphical notation)
are direct acyclical graphs in which nodes represent
casual variables (which can have any value) and arcs express dependecies
among them.
By using Bayes' inversion formula the conditional probability of the nodes
of the graph can be computed as information becomes available.
A causal net is isotropic, i.e. it can be used to perform inferences in both
ways, top-down (to "predict" an event) and bottom-up (to "diagnose" an event).
Pearl thinks that experience is transformed into causal models so that it
be possible for the mind to make decisions.
Pearl's belief function measures how close a proposition is to necessity,
as opposed to classic probability which measures how close a proposition is
to truth.
Peirce Charles: COLLECTED PAPERS (Harvard Univ Press, 1931)
Peirce devised a graphical notation to express logical relationships alternative
to Peano's linear notation. Peirce then defined a set of operations to
manipulate such graphs which conserve truth (equivalent to inference rules).
Peirce's "existential graphs" can represent first-order predicate logic as
well as modal logic (through colored contexts) and higher-order logics.
The theory of signs was originally developed by Charles Peirce and then revised
by C.W. Morris.
A sign is
something that stands for something else. Syntax is the study of the
relations that signs bear to other signs. Semantics is the study of the
relations that signs bear to what they stand for. Pragmatics is the study of the
relations that signs bear to what they stand for and their users.
Icons are signs that work by virtue of a relation of resemblance to what they
stand for (e.g., photographs).
Indices are signs that work by virtue of a relation of cause or
effect with what they stand for. (e.g., dark clouds suggest rain).
Symbols are signs that work by virtue of a conventional association
to what they stand for (numbers, nouns, etc).
For all three categories of signs,
types are kinds of things, tokens are their instances.
Penfield Wilder: MYSTERY OF THE MIND (Princeton Univ Press, 1975)
Penfield showed that memory is distributed in the brain.
Penrose Roger: THE EMPEROR'S NEW MIND (Oxford Univ Press, 1989)
Penrose reviews the historical debate pro and cons Artificial Intelligence,
from Turing's test to Searle's chinese room experiment, and provides economical
and clear explanations of the mathematical tools involved, from Turing machines
to lambda calculus.
Following John Lucas, Penrose claims that
Goedel's theorem asserts the preminence of the human mind over the machine: some
mathematical operations are not computable, still the human mind can treat them
(at least to prove that they are not computable). Therefore Artificial
Intelligence is impossible.
Then Penrose surveys scientific theories, from Euclides' geometry to
Einstein's relativity.
A long introduction to quantum theory brings Penrose to prove its inadequacy
to deal with macroscopic phenomena.
"Central to our feelings of awareness is the sensation of the progression of
time". Penrose looks for the origin of time in cosmological models and in
the second law of thermodynamics.
After a short introduction to neuroscience, Penrose hints that
consciousness could be a quantum phenomenon.
Penrose Roger: SHADOWS OF THE MIND (Oxford University Press, 1994)
Click here for full review
Penrose Roger: THE LARGE THE SMALL AND THE HUMAN MIND (Cambridge Univ Press, 1997)
Penrose rehashes his theory of the universe and his theory of consciousness,
and responds to criticism by distinguished colleagues. Goedel's theorem implies
that thinking must be non-computational. Penrose carefully separates
determinism from computation and looks for a deterministic but noncomputational
solution to the puzzle of consciousness. The solution lies in "objective
reduction", a type of collapse of the wave function which occurs when the
universe must choose between significantly differing spacetime geometries.
Objective reduction controls the operation of the brain through its effects on
coherent flows inside microtubules of the cytoskeleton.
Pereira Nelson & Grosz Barbara: Natural Language Processing (MIT Press, 1994)
A collection of articles from the Journal of Artificial Intelligence.
Piaget Jean: EQUILIBRATION OF COGNITIVE STRUCTURES (University of Chicago Press, 1985)
Piaget's theory of knowledge (or genetic epistemology)
Knowledge is constructed by each individual through her interaction with
the environment, knowledge is a developing relationship between the individual
and her environment. Knowledge is not simply absorbed, but it is also organized,
for the purpose of adaptation.
Knowledge develops through a process of self-organization based on feedback
from the environment.
The goal is to reach a sequence of progressive states of equilibrium through
a process of "equilibration". Development is viewed as a progressive
equilibration leading from a lesser to a higher state of equilibrium, i.e.
as a progressive increase in equilibrium.
The passage from one equilibrium state to the next is driven by maturation
(physiological growth of hereditary structures), experience and social
transmission, besides equilibration.
At different ages (developmental stages) the child exhibits different
knowledge structures. The stage of sensory-motor behavior include:
a stage of hereditary reflexes,
a stage of acquired adaptations (one to four months),
a stage of circular reactions (four to eight months),
a stage of intentional behavior (eight to twelve months),
a stage of directed groping (twelve to eighteen months),
a stage of symbolic representation (eighteen to tweentyfour months).
Through them the individual develops from a biological organism to a social one.
At this point the child is beginning to symbolize. Thoughts are actions that
take place in the mind, and Piaget calls them "operations". At this point
cognitive development begins. From concrete operations (seven-twelve years)
the child moves on to formal operations (twelve-fifteen years) and eventually
to the hypothetico-deductive thinking of adults.
The construction of stages proceeds according to a law of temporal
displacement, i.e. it is a nonlinear process of continous reconstruction
of the constructions of earlier stages (relearning) at a higher level.
This reconstruction provokes reflective abstraction, or reorganization of
knowledge at a higher level.
Cognitive structures are forms of equilibrium between the individual and the
environment. At each stage of development the process of equilibration is
repeated. At each stage of equilibrium there is an urge toward adaptation
based on feedback from the environment. At every cycle the structures of
thought ("structures d'ensemble") become more sophisticated.
Progress is driven by the need to find solutions to current problems and
anticipating possible ones.
In the process of cognitive development a number of events occur:
decentration (the individual becomes less and less egocentric),
internalization (of action), temporal displacement, reflective abstraction,
and awareness. Following Claparede, Piaget
thinks that as long as the individual can cope with the environment she
does not develop self-consciousness.
Pinker, Steven: WORDS AND RULES (Basic, 1999)
Click here for the full review
Pinker Steven: HOW THE MIND WORKS (Norton, 1997)
Click here for the full review
Pinker Steven: THE LANGUAGE INSTINCT (William Morrow, 1994)
Click here for the full review
Pinker, Steven: THE BLANK SLATE (Viking, 2002)
Click here for the full review
Platts Mark: WAYS OF MEANING (MIT Press, 1997)
An introduction to philosophy of language.
Plotkin Henry: DARWIN MACHINES AND THE NATURE OF KNOWLEDGE (Harvard University Press, 1994)
The British psychologist Henry Plotkin defines knowledge as incorporating the
knower. His focus is on the harmony established over the centuries between the
organization and structure of a living being and the world it inhabits.
Adaptation is the act of incorporating the outside world into the organism's
structure and organization. More properly, this is "biological" knowledge.
But human knowledge is simply a subset of biological knowledge. Plotkin
therefore advocates a science of knowledge that would be based on evolutionary
theory. Darwinism is likely to become the basis of all science, the idea
spreading beyond biological evolution. Plotkin views brains themselves as
Darwin Machines (just like Calvin). "Universal darwinism" will be a theory
based on darwinism but general enough to encompass everything. A likely
candidate structure for an empirical science is one based on the concepts
of replicator (an entity that can make copies of itself) and interactor
(an entity that can propagate replicators in space and conserve them in time
while interacting with the environment). The presence of this combination is
evidence that evolutionary algorithms are at work. They occur in life, in
the brain, in the immune system, in memes.
Plotkin Henry: THE ROLE OF BEHAVIOR IN EVOLUTION (MIT Press, 1988)
A collection of essays that deal with behavior as a cause of evolution.
Evolution determines behavior, but Plotkin and others believe that, in turn, behavior determines evolution.
In 1960 the British biologist Conrad Hal Waddington pointed out that animals can choose the environment where they will live and therefore pass on to future generations a new class of selective pressures, indirectly influencing their evolution.
Plotkin builds upon Waddington's intuition.
What an individual does affects the evolution of its species.
Individual behavior causes an acceleration in population evolution because it exposes the phenotype to a broader range of selection pressures than it would otherwise not experience.
David Hull discusses interactors and replicators in general.
Replicators are units that reproduce their structure directly. Interactors are entities that interact directly with their environment. The difference between Hull's interactors and Dawkins' "vehicles" is not trivial: genes are both replicators and interactors (they have a physical structure that interacts with an environment), and some interactors are also replicators (the paramecium that splits in two).
Robert Brandon, inspired by Lewontin and others, offers a hierarchy of interactors. The biosphere is hierarchically arranged and selection operates at all levels.
Robert Brandon defines natural selection as the process of differential reproduction due to differential fitness to a common selective environment. The "selective" environment (measured in terms of the relative fitnesses of different genotypes across time or space) is distinguished from the "external" environment and the "ecological" environment (measured using the organism itself as the measuring instrument so that only that part of the external environment that affects the organism's contribution to population growth is taken into account). The selective environment is the one that is responsible for natural selection.
Plotkin Henry: EVOLUTION IN MIND (Allen Lane, 1997)
Plotkin provides a delightful
introduction to evolutionary psychology via ethology and sociobiology,
assuming the tenet that most of an animal's behavior is functional to
survival and hard-coded in its genes by evolution (we are "bundles of
adaptations").
Nurture has nature: predispositions form and then execute.
The book reviews several theories by contemporary thinkers to frame the
borders of evolutionary psychology, from child development to Dawkins'
memes.
Plotkin Henry: LEARNING, DEVELOPMENT, AND CULTURE (Wiley, 1982)
A collection of essays on evolutionary epistemology (evolution as a knowledge process) and classic papers on evolution (Bateson, Campbell, Popper,
Lorenz, Mayr, Piaget, Waddington, Williams).
founded by Donald Campbell on pioneering ideas by Popper
similarities between bioogical and sociocultural evolution
Polya George: MATHEMATICS AND PLAUSIBLE REASONING (Princeton Univ Press, 1954)
A multi-volume survey of plausible reasoning.
Plausible reasoning is what supports and yields human knowledge of the world,
as opposed to demonstrative reasoning, which is incapable of yielding new
knowledge.
Volume one is devoted to induction and analogy.
Volume two is devoted to patterns of plausible inference,
nondemonstrative thinking and the theory of probability.
Plotkin Henry: EVOLUTION IN MIND (Allen Lane, 1997)
Click here for the full review
Polya George: COLLECTED PAPERS (MIT Press, 1974)
Four volumes of collected papers.
Polya George: HOW TO SOLVE IT (Doubleday, 1957)
This thin book summarizes Polya's studies on the methods of solving
mathematical problems. Polya's mathematics is not a monolotic deductive
system in which the mathematician is a mindless machine performing mechanic
operations, but an open game in which the mathematician must create a plan for
achieving the desired solution. The book is written as a tool for teachers and
students, but it really offers a comprehensive analysis of heuristic reasoning,
from analogy to generate and test.
Polya George: MATHEMATICAL DISCOVERY (Wiley, 1965)
A textbook on understanding, learning and teaching problem solving. Polya defines "heuristic" the study of the methods for problem solving.
Polya describes general, recurring patterns of behavior in trying to solve problems.
Popper Karl: THE LOGIC OF SCIENTIFIC DISCOVERY (Hutchinson, 1959)
Popper challenged logical positivism's hypothetico-deductive model of theory
formation. Criticizing any inductive form of reasoning that attempts
to derive a general proposition from specific instances, Popper proposes
to focus on demonstrating that hypotheses are false.
The scientific process should be one of conjectures and refutations.
Popper Karl & Eccles John: THE SELF AND ITS BRAIN (Springer-Verlag, 1977)
Popper's interactionism is "tri-alist": abstract objects of mathematics,
scientific theories and art products are examples of activities that
belong to neither the mental world nor the physical world. Mind plays the role
of intermediary between the imaginary world (World 3) and the real world
(World 1).
The mind is basically an operator that related abstract objects and physical
ones.
Since the mental world and the physical world are distinct,
mental states cannot be physical states.
"Downward causation" operates from World 3 to World 1.
Natural selection does not apply to World 3 and the mind as it does to World 1.
In World 3 and the mind the application of trial and error does not entail
the violent elimination of some of the individuals which are the objects of
the test. Natural selection trascended itself when it brought about the
emergence of mind and of World 3.
Along the way Popper also offers a comprehensive introduction to the
mind-body problem (Aristotle, Descartes, Leibniz, etc).
Eccles provides a comprehensive view of neural processes underlying various
cognitive functions. Then he advances his theory of the self-conscious mind
and the brain: the mind is an independent entity that exercises a controlling
role upon the neural events of the brain by virtue of its interaction across
the interface between
World 1 and World 2. The mind is always searching for brain events that are
interesting for its goals.
Popper Karl: KNOWLEDGE AND THE BODY-MIND PROBLEM (Routledge, 1994)
In these lectures Popper recapitulates his theory of the mind.
Popper distinguishes objective knowledge ("I know that water is liquid") from
subjective knowledge ("I know that I am wrong").
Popper posits the existence of a first world (the world of physical bodies), a
second world (the world of mental states) and a third world (the world of
products of the mind). The second world communicates with both the others.
Objective knowledge belongs to the third world. The third world evolves through
the growth of objective knowledge. Objective knowledge confers a degree of
autonomy to the third world (numbers are created by the mind, but then
mathematical laws determine what happens to them, regardless of the mind).
Popper derives biological phenomena of survival and evolution from the same
formula that determines the growth and evolution of objective knowledge
(basically, trial and error).
Consciousness emerged evolutionary with the faculty of language.
Consciousness emerges during growth with the faculty of language.
Therefore it must be related to the brain region that deals with speech.
Porges Stephen & etc.: PSYCHOPHYSIOLOGY SYSTEMS PROCESS (Guilford, 1986)
A collection of articles on psychophysiology, a close relative of cognitive
neuroscience which investigates psychological phenomena from their physiological bases.
Chapters are devoted to attention, memory, learning, emotion, stress, sexuality.
Port Robert & Van Gelder Timothy: MIND AS MOTION (MIT Press, 1995)
A collection of papers on the dynamical approach to cognition.
Posner Michael: FOUNDATIONS OF COGNITIVE SCIENCE (MIT Press, 1989)
A monumental, comprehensive introduction to the field by a number of
distinguished authors. Includes chapters on cognitive architectures (such as
ACT and SOAR), connectionism, model-theoretic semantics, neurophysiology,
discourse, mental models, vision, memory, action, etc.
Power Michael: COGNITION AND EMOTION (Psychology Press, 1997)
A survey of philosophical and psychological studies on the relationship
between emotion and cognition, with an attempt to integrate the two.
Priest Stephen: THEORIES OF MIND (Houghton Mifflin, 1991)
Priest provides a good, scholastic, down-to-earth coverage of
dualism (Plato and Descartes), monism (Spinoza, Russell),
behaviorism (Hempel, Ryle, Wittgenstein)
idealism (Berkeley, Hegel), materialism (Place, Davidson, Honderich, Putnam,
Lewis) and phenomenology (Husserl).
Pribram Karl: LANGUAGES OF THE BRAIN (Prentice Hall, 1971)
Pribram's holonomic model of memory is based on the hologram.
Memory is distributed in the brain. Memories do not disappear all of a sudden,
but slowly fade away. This is consistent with Penfield's experiments.
A sensory perception is transformed
in a "brain wave", a scheme of electrical activation that propagates through
the brain just like the wavefront in a liquid. This crossing of the brain
provides the interpretation of the sensory perception in the form of a
"memory wave", which in turn crosses the brain. The various waves that travel
through the brain can interfere. The interference of a memory wave and a
visual wave generates a structure that resembles an hologram.
Consciousness is due to fields within the cerebral hemispheres. Because of the physical properties of fields, they can store information in a form analogous to holograms.
Pribram Karl & Eccles John: RETHINKING NEURAL NETWORKS (Lawrence Erlbaum, 1993)
Proceedings of a conference on neurodynamics. Includes R.L. Dawes'
"Advances in the theory of quantum neurodynamics".
Pribram Karl: BRAIN AND PERCEPTION (Lawrence Erlbaum, 1990)
A collection of lectures that review Pribram's holographic (or, better,
"holonomic") theory of the brain.
The theory employs Fourier transformations to deal with the dualism between
spacetime and spectrum, and Gabor's phase space to embed spacetime and spectrum.
All perceptions (and not only colors or sounds) can be analyzed into their
component frequencies of oscillation and therefore treated by Fourier analysis.
Dirac's "least action principle" (which favors the least expenditure of energy)
constrains trajectories in such a space. Gabor's uncertainty principle sets a
limit with which both frequency and spacetime can be concurrently
determined (the fundamental minimum is Gabor's "quantum of information").
A rigorous description of transformations leading from perceptions to feature
extraction is provided for a variety of visual and cognitive activities.
Processes local to specific brain regions are studied in neurophysiological
detail.
Pribram expresses a few innovative viewpoints along the way.
Both distributed and localized functions characterize brain functions.
Structure and process are two aspects of the same entity, distinguished only
by the scale of observation (from a distance an entity looks like a structure,
but close enough it is a process).
The formalism of quantum theory applies to the modeling of brain functions
such as vision (brain microprocesses and physical microprocesses can be
described by the same formalism).
Pribram Karl: ORIGINS (Lawrence Erlbaum, 1994)
Proceedings of a conference on neurodynamics.
Contributions by Prigogine ("mind and matter: beyond the cartesian dualism"),
P.J. Werbos ("self-organization"), J. Gyr ("psychophysics"), C. Game
("non-equilibrium thermodynamics and the brain"), and neurophysiological models.
Pribram Karl & Broadbent Donald: BIOLOGY OF MEMORY (Academic Press, 1970)
A collection of articles on models of memory. It includes Endel Tulving on different retrieval mechanisms for short- and long-term memories.
Price Huw: TIME'S ARROW AND ARCHIMEDE'S POINT (Oxford University Press, 1996)
The australian philosopher Huw Price advances a solution to the biggest dilemma
of Quantum Physics: the mystery of the collapse of the wave function.
He starts by examining asymmetry in Physics: the asymmetry of Thermodynamics,
due to the second law, the asymmetry of radiation and the asymmetry of
cosmology (entropy was very low at the beginning, will be very high at the
end). Richard Feynman and John Wheeler had offered an explanation to
unify all asymmetries, but Price thinks that all asymmetries must instead be
reduced to a fundamentally coordinated behavior of the universe. The preferred
direction from the past to the future is due to the fact that our universe
contains sources of coordinated behavior.
Nonetheless, Price believes that our theories are asymettric because we
are conditioned by folk concepts of causality. Physical theories are built
starting with the assumption that the future cannot influence the past, and
therefore it is no surprise that they prescribe that the future cannot
influence the past.
Price thinks that backward causation (that future can influence the past), or
advanced action, is a legitime option. By using it, one redraws the laws of
Quantum Physics and finds that Einstein was right with his hypothesis of
hidden variables, that Quantum Physics provides an incomplete description of
the universe. A complete Quantum Physics will not assign any critical role
to the observer.
Priest, Stephen: THEORIES OF THE MIND (Houghton Mifflin, 1991)
A collection of seminal papers on the various schools of philosophy of mind
(materialism, dualism, behaviorism, etc).
Prigogine Ilya: THE END OF CERTAINTY (Simon & Schuster, 1997)
Prigogine investigates the role of irreversibility in nature.
The arrow of time, as expressed by biological, geological and cosmological
evolution, is not only a subjective illusion, it is a fundamental property of
nature.
A widespread interpretation of macroscopic irreversibility of things is that
it simply arises from our ignorance of the microscopic state of things.
Prigogine counters this argument by stating that unstable systems are real and
that it is instability that breaks the symmetry of time. It does so because
instability requires probability (the evolution of an unstable state can only
be described as a range of probable evolutions) and probabilities introduce
irreversibility. Stable systems allow for certitude, but unstable systems only
allow for probabilities, and probabilities cannot be undone.
Instability also solves the dilemma of the quantum observer: it is not the
observer that breaks the symmetry of time, it is the instability related to
the observation.
The Prigogine shows that, far from being an illusion, the arrow of time is
a source of order in nature.
Prigogine Ilya: INTRODUCTION TO THERMODYNAMICS OF IRREVERSIBLE PROCESSES (Interscience Publishers, 1961)
Prigogine introduced the minimum entropy principle (stable near-equilibrium
dissipative systems minimize their rate of entropy production)
to characterize living organisms.
Prigogine Ilya: FROM BEING TO BECOMING : TIME AND COMPLEXITY IN THE PHYSICAL SCIENCES (W. H. Freeman, 1980)
In classical and quantum Physics, equations are invariant with respect to
time inversion. Future and past are equivalent. Time is only slightly
different from space. Time is therefore a mere geometrical parameter. And
Physics offers a static view of the universe. The second law of Thermodynamics
made official what was already obvious: that many phenomena are not reversible,
that time is not merely a coordinate in space-time. Irreversible processes
are not only ubiquitous but they also play a fundamental role in biological
phenomena.
Prigogine shows, using Boltzmann's theorem, that irreversibility is the
manifestation at macroscopic level of randomness at microscopic level.
A theory of "instability", based on Aleksander Lyapounov's, is made necessary
by two observations: that
classical Thermodynamics is about destruction of structure, while
structures spontaneously appear in nature; and that
near instabilities large fluctuations invalidate probability theory (upon which
Thermodynamics is founded).
Prigogine attempts a microscopic formulation of the irreversibility of laws of
nature. He associates macroscopic entropy (or Lyapounov functions) with a
microscopic entropy operator. Time too becomes an operator, no longer a mere
parameter. Both time and entropy are therefore operators.
This way, Prigogine turns the table around: instead of having a basic theory
expressed in terms of wave functions (i.e., of individual trajectories), he
obtains a basic theory in terms of distribution functions (i.e., bundles of
trajectories). Time itself depends on the distribution and therefore becomes
itself a stochastic quantity, just like entropy, an average over individual
times. As a consequence, just like entropy cannot be reversed, time cannot:
the future cannot predicted from the past anymore.
This formulation unifies physical and biological phenomena.
Traditionally, physical space is geometrical, biological space (the space in
which biological form develops) is functional
(for example, physical time is invariant with respect to rotations and
translations, biological space is not).
This is the concept of time used by Nicholis and Prigogine in their
"bifurcation theory" (Thom's catastrophe theory being a particular case).
Prigogine Ilya & Stengers Isabelle: ORDER OUT OF CHAOS (Bantham, 1984)
This is the english edition of "La Nouvelle Alliance" (1979). Prigogine
analyzes the history of science and scientific thought and derives
a new vision of the world.
Living organisms function as dissipative structures, structures that form as
patterns in the energy flow and that have the capacity for self-organization
in the face of environmental fluctuations.
Dissipative systems maintain their structure by continous dissipation of
energy.
Classical science (and quantum mechanics) describes a world as a static and
reversible system that undergoes no evolution, whose information is constant
in time. On the other hand the second law of thermodynamics describes the
world as evolving from order to disorder, while biological evolution is
about the complex emerging from the simple (structure, i.e. order, arises
from disorder). Irreversible processes are an essential part of the universe.
Conditions far from equilibrium foster phenomena such as life that classical
physics does not cover.
Prigogine focuses on the peculiar properties exhibited by
systems far from equilibrium.
Non-equilibrium conditions favor the spontaneous development of
self-organizing systems (i.e., dissipative structures), which maintain
their internal organization, regardless of the general increase in entropy,
by expelling matter and energy in the environment. Most of Nature is made of
dissipative systems, of systems subject to fluxes of energy and/or matter.
Dissipative systems conserve their identity thanks to the interaction with
the external world.
The concept of organization is deeply rooted in the physical universe.
Prigogine considers living organisms as dissipative structures in states of
non-equilibrium. A system that is not in equilibrium exhibits a variation of
entropy which is the sum of the variations of entropy due to the internal
source of entropy plus the variation of entropy due to the interaction with
the external world. The former is positive, but the latter can equally be
negative. Therefore total entropy can decrease.
An organism "lives" becausa it absorbs energy from the external world and
processes it to generate an internal state of lower entropy.
An organism "lives" as long as it can avoid falling in the equilibrium state.
Probability and irreversibility are closely related. Boltzman had already
proved that entropy grows because probability grows.
Prior Arthur: PAST, PRESENT AND FUTURE (Clarendon Press, 1967)
Prior's temporal logic assumes that the temporal reference is negligible and
therefore provides an underlying theory for an
instant-based ontology (as opposed to the interval-based ontology) of Time.
Time is formalized by means of modal operators that express properties such as
"always" and "sometimes", "before" and "after", "while" and "when".
Prior's theory finds a logical correspondent to many past and future tenses
by reducing them to two fundamental modal operators, one for the past and one
for the future. Nonetheless, Prior cannot represent "since" and "until", which
can easily be expressed by classical logic.
Prior Arthur: WORLDS, TIMES, AND SELVES (Duckworth, 1977)
Prior investigates structural analogies between modal logic (the formal study
of necessity and possibility) and quantification theory (the formal study of
universality and existentiality) and develops a modal system Q with
an operator Q that picks out instants, worlds, or selves, as the case may be.
Purves Dale: NEURAL ACTIVITY AND THE GROWTH OF THE BRAIN (Cambridge Univ Press, 1994)
Brain cells are in a continual state of flux, creating and destroying synapses
all the time. Neural activity caused by external stimuli is responsible for
the continual growth of the brain, and for sculpting a unique brain anatomy in
every individual based on the individual's experience.
Putnam Hilary: MIND, LANGUAGE AND REALITY (Cambridge Univ Press, 1975)
The same mental state may be implemented by different physical states.
Putnam imagines a world called "Twin Earth" exactly like Earth in every respect
except that the stuff which appears and behaves like water, and is actually
called "water", on Twin Earth is a chemical compound XYZ. If one Earth and one
Twin Earth inhabitant, identical in all respects, think about "water", they
are thinking about two different things, while their mental states are
absolutely identical. Therefore the content of a concept depends on the context
("externalism"). Meanings are not in the mind, they also depend on the objects
that the mind is connected to.
Putnam classifies mental states based on their function, i.e. their causal roles
withing the mental system, regardless of their physical structure.
Putnam originally suggested that the psychological state of an individual
be identified with the state of a Turing machine. A psychological state would
cause other psychological states according to the machine's operations.
Belief and desire correspond to formulas stored in two registers of the machine.
Appropriate algorithms process those contents to produce action.
Putnam Hilary: REASON, TRUTH AND HISTORY (Cambridge Univ Press, 1981)
Putnam provides a formal proof that model-theoretic semantics fails as a theory of meaning, because he found a fundamental contradiction between the definition of meaning in model theory (a function which assigns a truth value to a sentence for all possible cases) and the constraint that the meaning of the parts cannot be changed without changing the meaning of the whole.
Putnam proves that meaning does not stand in the realtionship between symbols
and the world.
His criticism of symbol systems is based on the observation that, since we are part of reality, there can be no complete and true description of the world: we are part of the reality that we observe, we cannot claim the role of independent observer.
The definition of truth depends on the meaning of the words of the language
and each definition of truth should list all conditions that meaning depends
on (including the definition of truth which is being defined).
Putnam Hilary: REPRESENTATION AND REALITY (MIT Press, 1988)
Putnam abandons his functionalist theory of the brain.
Mind cannot comprehend itself. An automaton cannot explain its own behavior.
The same mental state may be implemented by different computational (functional)
states, therefore mental states cannot be computer programs.
Explanation and prediction of intentional phenomena such as belief and desire
belong to the realm of interpretation: concepts do not exist in the mind,
are the output of interpretation. Interpretation can be "normative", when it
employs Davidson's principle of charity or Dennett's principle of "rationality",
which state that an organism behaves as it should given the circumstances
(most of its beliefs are true, it believes in the implications of its beliefs,
no two beliefs contradict each other, and so on); or "projective" (Stitch),
when it attributes to an organism the propositional attitudes that we would
have were we in its situation.
Meaning exhibits an identity through time but not in its essence (such as
momentum, which is a different thing for Newton and Einstein but expresses the
same concept). An individual's concepts are not scientific and depend on the
environment. Most people know what gold is, and still they cannot explain
what it is and even need a jeweler to assess whether something is really gold
or a fake. Still, if some day we found out that Chemistry has erred in
counting the electrons of the atom of gold, this would not change what it is.
The meaning of the word "gold" is not its scientific definition, but the
social meaning that a community has given it.
It is not true that every individual has in its mind all the knowledge needed
to understand the referent of a word. There is a subdivision of competence among
human beings and the referent of a word is due to their cooperation.
Meaning is not in the mind.
Pylkkanen Paavo: MIND, MATTER AND ACTIVE INFORMATION (Univ. of Helsinki, 1992)
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Pylyshyn Zenon: COMPUTATION AND COGNITION (MIT Press, 1984)
Zenon Pylyshyn believes in a variant of Fodor's language of thought.
He has applied that theory to the debate on mental imagery, his
"descriptionalism" being opposed to Stephen Kosslyn's pictorialism.
Pylyshyn recognizes three levels of description for cognitive tasks: the
knowledge level (which explains actions of the system as functions of what
it knows and its goals), the symbolic level (which codifies the semantic
content of the knowledge and the goals), and the physical level. Unlike Marr,
Pylyshyn believes that all three levels must be studied to understand
cognitive functions.
The primitive operations of the mind's cognitive architecture can be
recognized because they are those defined solely by the biology of the brain,
that is those that cannot be altered by no other cognitive activity, that
are "cognitively impenetrable".
Images are simply the product of the manipulations of knowledge encoded in the
form of propositions.