Transcript Reactivity & Reductionism

Reactivity
&
Reductionism
Descartes & reductionism
Descartes introduced
reductionism, the study of the
world as an assemblage of
physical parts that can be
broken apart and analyzed
separately.
[Edward O. Wilson. Consilience. The unity of knowledge. A.A. Knoff. New York. 1998, p. 29]
REDUCTIONISM
 Since the 17th century, the mechanistic reductionist world view
associated with Descartes has dominated European and American
thought about nature and society.
 According to this view, the world is made up of separate objects,
things.

These things are essentially passive; they normally remain the way
they are but can be set in motion by external causes.
 They can be examined in isolation from each other and their
properties measured. The resulting quantitative differences are the
most important things about them.
 Finally, once we have measured and described them, we can combine
them into structures that will behave according to the properties
analyzed in isolation.
Richard C. Lewontin & Richard Levins, 1988
Stimulus - Reaction
Stimulus  Reaction
Today
 A fundamental issue in neurobiology is how
sensory stimuli guide motor behavior
A major component of this problem
involves understanding how the brain
represents sensory features (p. 487)
Ranulfo Romo & Emilio Salinas.
Sensing and deciding in the somatosensory system//
Current Opinion in Neurobilogy
1999, 9: 487-493
Reductionism & Fun
While Occam’s razor is a useful tool in the physical
sciences, it can be a very dangerous implement in
biology
Francis Crick
( … a vigorous habitual reducer …)
It is, of cause, always more fun reducing
than being reduced.
… Crick finds the over-simplicity of the physicists’ view of his own
subject much more obvious than his own over simplicity in
approaching the social sciences and humanities.
[Mary Midgley. The ethical primate. Humans, Freedom and Morality. London & New York.
Routledge. 1994, pg. 38.]
THE FRAGMENT OF THE RATIONALE OF THE
SYMPOSIUM “PERILS AND PROSPECTS OF
TNE NEW BRAIN SCIENCES”
(Stockholm, September 15 – 19, 2001)
The dominant tendency amongst
neurobiologists is severely
reductionist, whilst by contrast
amongst psychologists there remain
strong anti-reductionist predilections.
Reductionism
The Scientific Belief
A Scientific Theory of the
Mind
Our minds – the
By “scientific” … I mean a
behavior
of
our
description based on the
brains – can be neuronal and phenotypic
explained by the organization of an
interactions of nerve individual and formulated
cells (and other cells) solely in terms of
physical and chemical
and the molecules
mechanisms giving rise
associated with them.
to that organization.
[F. Crick. The Astonishing Hypothesis. New
York: Charles Scribner’s Sons. 1994, p.7]
[G.M. Edelman. The remembered Present.
New York: Basic Books. 1989, pp. 8-9]
THE CARTESIAN THEATER
Descartes held that for an event to reach
consciousness, it had to pass through a special
gateway … which Descartes located in the pineal
gland or epiphysis. But everybody knows that
Descartes was wrong (?!-Yu.I.A.). Not only is the
pineal gland not the fax machine to the soul; it is not
the Oval Office of the brain. It is not the “place
where it all comes together” for consciousness…
I call this mythic place in the brain where it all
comes together … the CARTESIAN THEATER.
Dennett D.C. Brainchildren. Essays on Designing minds. Penguin Books: London,
1998, p.132
THE NEURAL BASIS OF ROMANTIC
LOVE
• Nothing is known about the neural substrates involved in
evoking one of the most overwhelming of all affective
states, that of romantic love.
• The activity in the brains of 17 subjects who were deeply
in love was scanned using fMRI, while they viewed
pictures of their partners.
• The activity was restricted to foci in the medial insula and
the anterior cingulate coretx and, subcortically, in the
caudate nucleus and the putamen.
• A unique network of areas is responsible for evoking
this affective state.
Bartels A. & Zeki S. Neuroreport. 2000, 11 (17): 3829-34
Localization of Intelligence
A recent study by Duncan et al.
[7] has found evidence that
general intelligence is
localized to regions of the
lateral prefrontal cortex.
M. Atherton et al. Cognitive Brain Research, 16 (2003) 26-31, pg. 27
THE CONNECTIONS EXISTING
BETWEEN THE LIMBIC SYSTEM
AND THE PREFRONTAL CORTEX
OFFER A MATERIAL BASIS FOR
RELATIONSHIPS BETWEEN THE
EMOTIONAL AND COGNITIVE
SPHERES
[Changeux J.-P. & Dehaene S. Neuronal models of cognitive functions.
Cognition, 1989, 33, 63-109]
C- and U-neurons
“I divide the nervous system into two types of
neurons, those concerned with consciousness,
“C” neurons, and those which take care of
unconscious functions, “U” neurons (the use of
the word “neuron” in this context is shorthand for
“otherwise unspecified subpart of the brain”).
The goal of anesthesia is to interfere temporarily
with the function of C neurons without disturbing
the U neurons.”
[John C. Kulli. Is Searle conscious? BBS, 1990, 13:4, 614]
Left: microtubule, a cylindrical lattice of tubulin
proteins. Right: coupled to position of a pair of
quantum coupled electrons in an internal
hydrophobic pocket, each tubulin may occupy two
classical conformations (top) or exist in quantum
superposition of both conformational states (bottom).
A tubulin may thus act as a classical bit (top) or as a
quantum bit, or ‘qubit’
Microtubule simulation in which classical computing
(step 1) leads to emergence of quantum coherent
superposition and quantum computing (steps 2, 3)
in certain (gray) tubulins. Step 3 (in coherence
with other microtubule tublins) meets critical
threshold related to quantum gravity for
selfcollapse (Orch OR). A conscious event (Orch
OR) occurs in the step 3 to 4 transition. Tubulin
states in step 4 are noncomputably chosen in the
collapse, and evolve by classical computing to
regulate neural function. (b) Schematic graph of
proposed quantum coherence (number of
tubulins) emerging versus time in microtubules
(MTs). Area under curve connects superposed
mass energy E with collapse time T in accordance
with E=h−bar/T. E may be expressed as Nt, the
number of tubulins whose mass separation (and
separation of underlying space time) for time T
will selfcollapse. For T=25 ms (e.g. 40 Hz
oscillations), Nt=2×1010 tubulins.
Conduction pathways in microtubules, biological quantum
computation, and consciousness
S. Hameroff , A. Nip, M. Porter, J. Tuszynski
Byosystems,2002,64,149-168
FROM PREPARATION
TO THE BEHAVIOR

Predictions are
fallacious
Many results regarding ...
physiology and
pharmacology during
anesthesia cannot be
extrapolated to behavioral
conditions
[West M.R. Anesthetics eliminate somatosensory-evoked discharges
of neurons in the somatotopically organized sensorimotor
striatum of the rat. The Journal of Neuroscience, 1998,18, 90559068]
Reductionism and fundamental
understanding
Continued reductionism and
atomization will probably not,
on its own, lead to fundamental
understanding.
[Koch Ch. & Laurent G. Complexity And The Nervous System. Science, 1999,
284, 96-98]
REDUCTIONISM & $
• The most productive scientists, installed in
million-dollar laboratories, have no time to
think about the big picture and see little
profit in it.
• The eyes of most leading scientists, alas, are
fixed on the GOLG.
• It is therefore not surprising to find physicists
who do not know what a gene is, and
biologists who guess that string theory has
something to do with violins.
[Edward O. Wilson. Consilience. The unity of knowledge. A.A. Knoff.
New York. 1998, pp. 31, 39]
Behaviorism represented an important, progressive force. BUT
ALL THINGS MUST END, WHETHER GOOD OR BAD,
†and behaviorism began to give way in the final decades of the 20th century †
BUT
Explanatory reductionism still reigns
in biology, neurobiology, and in much of cognitive science. BUT
Now, however, this strategy is starting to show signs of strain around the edges
It is weak when it comes to supplying explanations for many biological
problems that involve numerous components interacting as a system.
New ways of thinking are needed to grapple with these problems
Systems level of explanations are both possible and achievable.
The essence of Aristotle’s
teleology is thus his rejection
of a reductive understanding
of living things.
The central thesis of Aristotle’s
anti-reductive view is that the
change by which the form of a
mature animal or plant comes to
be in appropriate matter cannot
be understood solely in terms of
…. the elements, of which both
parent and offspring are
made.
Mirus C. V. ARISTOTLE’S TELEOLOGY AND
MODERN MECHANICS. A Dissertation, Notre
Dame, Indiana, 2004.
Aristotel (384-322 years BC)
Causes are the concern of the applied
sciences
“The prime aim of the physical sciences is not the discovery of causes or causes
chains... The study of the causes of this or that event is … always an application of
physics. It is, then, still in case where our interest is in how one might … produce
or counteract some spot-lighted development, that we talk about causes. … From
this we can see why the term “cause” is at home in the … applied sciences, such
as medicine and engineering, rather than in the physical sciences. For the theories
of the physical sciences differ from those of the diagnostic and applied sciences
much us maps differ from itineraries. In the physical sciences … the regularities
we find … are represented in a way which is application-neutral. …Simple chainlike prescriptions can be given only in restricted sets of circumstances: we can
confidently match causes and effects only in a given context. So once we shift
from the diagnostic to the physical sciences the idea of a causal chain is of as
little use as the term “cause” itself. ”
Stephen Toulmin The philosophy of science. Hutchinson’s university library, Hutchinson House,
London. 1958
PRO:
Development of Western science is based on two great achievements:
the invention of the formal logical system (in Euclidean geometry) by
the Greek philosophers, and the discovery of the possibility to find out
causal relationships by systematic experiment (during the Renaissance).
Albert Einstein
CONTRA:
“The prime aim of the physical sciences is not the discovery of causes
or causes chains... Causes are the concern of the applied sciences
[medicine, engineering, etc].”
Stephen Toulmin