Download Mechanisms and the Nature of Causation

STUART S. GLENNAN
MECHANISMS AND THE NATURE OF CAUSATION
In this paper I offer an analysis
ABSTRACT.
of causation
based upon a theory
a system's
nisms
"internal"
parts interact to produce
systems whose
complex
can be explained
I argue that all but the fundamental
laws of physics
behavior.
by
an epistemologically
to mechanisms.
Mechanisms
way
provide
unproblematic
of mecha?
"external"
reference
to explain
This
generalizations.
laws from other
the necessity
which
is often
taken to distinguish
account
to which
of necessity
leads to a theory of causation
according
reasons
related when
that connects
them. I present
there is a mechanism
account
of fundamental
physical
causation
does
not undermine
events
why
the mechanical
are causally
the lack of an
account.
1. HUME'S PROBLEM
[Experience
only teaches
us in the secret connexion,
us, how
which
one event
binds
constantly
them
together
follows
another,
and renders
them
without
inseparable
instructing
(Hume,
1777, p. 63).
to Hume,
cannot tell us about the "secret con?
according
binds together events. When we attend to a supposed causal
billiard ball colliding with a stationary
interaction, for instance, a moving
billiard ball, we can observe the motion of the first ball and then the motion
of the second, but we can not observe a connection
between
the two. Fur?
would
allow us to observe
thermore, no number of further observations
Experience,
nexion" which
any
connection.
Hume's
in nature,
is that, although we can observe
problem
we can never see the "secret connexion"
together. Itwould seem therefore
one event to follow another. His
define
the notion
regular conjunctions
which
binds them
that we can never have know what
causes
to this problem
is to
no reference
to
that it makes
solution"
"skeptical
in such a way
to constant conjunction.
of cause
a connection,
but only
He defines a cause to be
"an object, followed
by another, and where all the objects similar to the
first are followed
by objects similar to the second" (Hume, 1777, p. 76).
This definition
is the germ of the regularity theory of causation which has
of causation ever since.1
empiricist discussions
Hume's
can yield
Although
argument that no number of observations
an impression of a connection
in
at
view
is,
least, irrefutable, I do not
my
dominated
Erkenntnis
?
44:
1996 Kluwer
49-71,1996.
Academic
Publishers.
Printed
in the Netherlands.
STUARTS. GLENNAN
50
think that that argument requires us to adopt a regularity view of causation.
In this paper I will try to suggest an alternative
that I call a mechanical
behind
the
The
intuition
of
causation.
theory is straightforward.
theory
I claim that some event causes another event, say that my turning
When
I have
this simply because
the key causes my car to start, I do not believe
routinely
I believe
that turning the key is followed by the engine starting.
I believe
that connects
that there is a mechanism
observed
this because
to engine-starting.
I believe
that the key closes a switch which
key-turning
causes the battery to turn the starter motor and so forth. Furthermore,
this
I can look under the hood and see how the
is not a "secret connexion".
mechanism
There
works
works.2
is an obvious
to this sort of explanation.
it
Although
objection
the key starting the car, there is a very important
for instance, to look
for which
it does not. It is not possible,
for cases
class of cases
at the mechanism
like
which
causes
other. So far as we understand
attract each
to gravitationally
there is no
this interaction between bodies,
a
It
"brute
fact"
about the
it.
is
just
explains
two bodies
which
underlying mechanism
we
In this case we
live.
in
which
world
cannot
explain the interaction by
form of regularity
theory seems
theory is not that it is an incorrect
to any mechanism.
Here some
with
the
The
regularity
problem
plausible.
analysis of such cases, but that it fails to distinguish
The vast majority
there is a discernible mechanism.
reference
these from cases where
of cases are of the latter
sort.
My aim in this paper is to offer an analysis of the concept of mechanism.
can be put
of the paper I indicate how this analysis
the conclusion
I emphasize
the fact that this theory
to work
in a theory of causation.
I suggest that there should
in fundamental
cannot explain causation
physics.
the case of
between
of causation
in our understanding
be a dichotomy
At
fundamental
physics
and that of other
itself).
Mechanical
theories
the Mechanist
movement
of causation
sciences
(including
are not new.
The
much
central
of physics
tenet
of
century was that all natural
com?
as the result of the action of mechanisms
in the seventeenth
phenomena were explicable
To say that some event caused another event was
posed of corpuscles.3
the two, where
this
linkage between
just to say that there is a mechanical
or
a
as
bodies
was
of
collection
understood
larger rigid
corpuscles
linkage
to provide
movement
pushing on each other. The failure of the Mechanist
I
an enduringly
stems,
think, from two prob?
adequate account of causation
- one scientific and one
The scientific problem has
lems
epistemological.
of matter and
views about the microstructure
to do with the Mechanists'
the forces which
govern
interactions
between
matter. Mechanists
advocat
MECHANISMSAND THENATUREOF CAUSATION
51
style theories in which the universe consists of a large (or
of corpuscles which
interact with each other only by
infinite)
collision
of
(or perhaps more extended pushes). The admissible
principles
interaction are what we would
call "strictly mechanical
i.e.,
principles",
the sort of principles with which one would construct amechanical
(rather
ed Democritean
collection
non
than say an electronic)
device.
It was believed
that all apparently
mechanical
and magnetism,
could ultimately be
forces, such as gravitation
as
the
actions
of
mechanisms
of
explained
consisting
pushing
corpuscles
on each other. This point of view has proved untenable
in light of sub?
scientific
sequent
developments.
have resisted
Physical
forces
such as gravitation
and
narrowly mechanical
explanation.
with
Mechanism
has
problem
seventeenth-century
to do with the testability of mechanical
theories. Mechanist
explanations
are often dominated
of natural phenomena
by baroque accounts of mech?
anisms
that are not of discernible
(see, e.g., the
consequence
physical
electromagnetism
The epistemological
discussion
of gravity
in Descartes,
Descartes
and other
1664). Although
that all phenomena
claimed
could be explained
in terms of
of corpuscles,
size, shape and motion
very little was said about how these
and
their
could
be
observed
(or how we could make
corpuscles
properties
Mechanists
inferences
about
them on the basis
of observables).
that I will develop
is largely inspired by
I hope, however,
that my anal?
insights of the Mechanical
philosophers.
two
will
avoid
these
In
the
first
must be
mechanisms
ysis
pitfalls.
place,
in such a way that there are not a priori restrictions on the sorts
conceived
The
account
of allowable
of mechanisms
interactions
which
may take place
analysis of causal connections
when
there are ways
(even
between
a mechanism's
in terms of mechanisms
if indirect) of acquiring
of their parts and the interactions between
them.
knowledge
In the remainder of the paper I will present an account of mechanisms
and show how it provides
the foundation
for a theory of causation. Section
parts. Additionally,
is only meaningful
2 of
this paper presents my analysis
of mechanisms.
Section
3 applies
to two simple systems. Section 4 discusses
this analysis
some relation?
and laws. Section 5 shows how the analysis of
ships between mechanisms
can
mechanisms
be used to formulate a theory of causation.
2.
are two senses
There
AN ANALYSISOFMECHANISMS
in which
the term
'mechanism'
is commonly
used.
refers narrowly
to the internal works of machines,
as when
of a clock mechanism.
The second refers more generally
to
The first sense
one
speaks
complex
systems
analogous
to machines,
as when
one speaks
of a human
STUART S. GLENNAN
52
perceptual mechanism
marized
by a defmition
or a market
which
mechanism.
is meant
My
to capture
analysis can be sum?
this latter usage:
a behavior
is a complex
system which
underlying
that behavior by of the interaction of a number of parts
to direct causal laws.
A mechanism
(M)
produces
according
a behavior'
of a 'mechanism
Notice
that (M) is a definition
underlying
even
a
cannot
rather than amechanism
One
mechanism
simpliciter.
identify
without
does. The boundaries
of the
saying what it is that the mechanism
of it into parts, and the relevant modes
of interaction
these parts depend upon what the behavior we seek to explain.
Furthermore,
systems do many
complex
things at once. If one isolates a
one can identify
system by some kind of physical
complex
description,
system,
between
the division
ofthat
1970). A complex
system (Kauffman,
indefinitely many behaviors
its
different
behaviors.
has
mechanisms
many
system
underlying
behavior of complex
The polymorphous
systems can be illustrated by
the behaviors of the human body. Two of the many subsystems
considering
and respiratory
body are the cardiovascular
for
has
mechanisms
systems
doing certain things
and with
carbon-dioxide)
inhaling oxygen and exhaling
Each
of
of the human
systems.
these
(pumping blood,
regard to one of
interact in such a way
that
the two systems
blood)
(oxygenating
a
as
must
These
divide
the
considered
be
systems
body
composite.
they
it into the heart,
system divides
up in different ways. The cardiovascular
etc. The respiratory system divides it into lungs,
veins, arteries, capillaries,
these
etc. The physical
of the systems
extensions
diaphragm, windpipe, mouth,
there are, e.g., veins and arteries running through
and their parts overlap;
the various parts of the respiratory
system. The choice of decomposition
to be explained
into parts depends upon the capacity or behavior
(Wimsatt,
1972).
Although
the choice
of decomposition
are not merely
is being
upon what
depends
artifacts of the description. Veins
bodies, even though they overlap.
decompositions
explained,
and lungs are both really parts of human
are good descriptions
of mechanisms
Descriptions
what
is "really"
of
dependence
there. This
point deserves
decomposition
systematic
realism or relativism.
Simple examples
there is no such implication.
insofar as they describe
the context
emphasis because
to imply anti
such as the one above show that
is often
taken
was designed
amechanism
may be something
two
not
of a
behaviors
be. Consider
to do (or selected for), but it need
of heat.
of a drive shaft and the production
combustion
engine: the motion
Either of these behaviors may be legitimately
explained.
mechanically
The behavior
in question
MECHANISMS AND THE NATUREOF CAUSATION
However,
produced
or systems
is designed
the engine
a side-effect.
is merely
to move
When
the drive
one considers
53
shaft, while
designed
the heat
artifacts
con?
pressures,
explanatory
text often dictates analyzing
the system in terms of its production
of the
or selected behavior,
but one could choose any other behavior
designed
as
In
of these systems
well.
which
fact, one can investigate mechanisms
that have
evolved
under
selection
sense be said to have a purpose. One can con?
in any interesting
solar
the
the motions
of
sider, e.g.,
system as a mechanism
underlying
the earth (or the planets) even though one believes
that this motion
is not
cannot
purposive.4
In order
for (M) to be sufficiently
it is important that a very
general
of
entities
be
of
mechanisms.
Parts may be simple
may
parts
variety
or complex
in internal structure, they need not be spatially localizable,
and
in a purely physical
In certain
they need not be describable
vocabulary.
wide
to consider genetic
for instance, one might wish
contexts,
whose parts are genes or information processing mechanisms
are software modules
or data structures. There are, however,
mechanisms
whose
parts
certain kinds
of entities which, to prevent
to be parts of mechanisms.
robustness
(M) from being vacuous, should not be allowed
must have a kind of
The parts of mechanisms
from
their
within
that mechanism.
It
apart
place
and reality
to take the part out of the mechanism
should in principle be possible
and
consider its properties
in another context. Care must be taken so that parts
are neither merely properties
of the system as a whole nor artifacts of the
I shall summarize
these restrictions
descriptional
vocabulary.
by saying
that parts must be objects.5
can be illustrated by considering
The significance
of these restrictions
to give a mechanical
whether or not it is possible
of the behav?
explanation
ior of the electromagnetic
field (as it is codified by Maxwell's
I
equations).
in the only natural decomposition
it is not, because,
of the field into
parts, the parts of the system are not objects in my sense. This case is sig?
the electromagnetic
nificant because
field is an example of a law-governed
believe
entity whose behavior
The electromagnetic
is not subject to mechanical
explanation.
field is an important part of many mechanisms,
from particle accelerators
to TVs to the mechanism
which produces
the
It is probably fair to say that electromagnetic
Aurora Borealis.
fields play a
role in producing
the great majority
of physical phenomena.
Furthermore,
are
fields
electromagnetic
objects of a kind. They have a variety of prop?
erties
for instance energy and momentum.
The properties
of a field can
be completely
described
field
B.
magnetic
by two vector
fields,
the electric
field E and the
54
STUART
Is there amechanism
S. GLENNAN
that explains
the properties
of the electromagnetic
field? If there is, then it should be possible to decompose the field itself
into parts. There is at least one sense
to talk about the electric
appropriate
in which
this can be done.
It is quite
in a region - for
or magnetic
field
two capacitor plates, or the magnetic
instance, the electric field between
field of the earth. These fields are parts of the electromagnetic
field, if
as
we conceive
the entirety of space. What
of this field
jus?
occupying
is their relatively
these parts as objects
tifies characterizing
high degree
this kind of
from the field in surrounding
of separability
However,
space.
to describe a mechanism
that
of parts would not be adequate
articulation
an electromagnetic
field.
produces
articulation
into parts consistent
So far as I can see, the only possible
field
involves
of
the
with the classical
thinking
theory
electromagnetic
as
in
Each
of
these
of the parts of the field
space.
parts have the
points
fails
field strength. Such an analysis
of electric and magnetic
properties
in my sense. Such points are not
because points in space are not objects
to differentiate
It is not possible
in themselves.
isolable or manipulable
field that are suffi?
between points in the electromagnetic
experimentally
in
between
points
ciently close to one another. There are no boundaries
the
field
between
there are boundaries
in which
the way
between,
e.g.,
to alter
fields.6 It is not possible
the capacitor plates and the surrounding
at a single point. The points, while part of the
of the field as a whole, have no physical
signif?
account
It is crucial to a mechanical
icance apart from this description.
that a system display some behavior which can be explained by reference
But there are not, in this case,
of its constituents.
to underlying
properties
"Maxwell's
with underlying
constituents
properties. As Hertz remarked,
field
the electromagnetic
mathematical
description
equations".
theory isMaxwell's
be different
The situation would
if there were
a detectable
aether.
If
an underlying
of
for the transmission
medium
in any
to
then it might have been possible
and magnetic
electrical
disturbances,
of
Itmight have been composed
the properties of this medium.
investigate
these
how
forces
have
been
there
and
particles
explaining
might
particles
interacted when disturbed by external sources (a light bulb or whatever).
to our accepted physical
But according
theory there is no aether and there
sense
there were
is no mechanical
explanation
in any physically meaningful
between
The interactions
governed
Goodman.
of the electromagnetic
sense go deeper.7
field. One
cannot
then
to (M),
are, according
parts of mechanisms
as
same
the
use
term
in
here
'law'
I
the
laws.
way
essentially
by
which
universal
Laws are generalizations
sup?
(or
propositions)
port counterfactuals.
Lawlike
or nomic
generalizations
are distinguished
MECHANISMSAND THE NATUREOF CAUSATION
55
from accidental
because
accidental
offer
generalizations
generalizations
no such support (Goodman,
ch.
1947; Nagel,
1961,
4).
Some may
account of laws is not adequate
argue that Goodman's
because
it does not provide a criterion for demarcating
"deep" laws (like
law of universal
Newton's
from less interesting counterfactual
gravitation)
whenever
you leave bread on the counter
(like
supporting generalizations
for two weeks,
itmolds). Although
it is true that Goodman's
account does
not provide such a criterion, for the purposes of my account of mechanisms,
the lack of a clear distinction
between
these two sorts of counterfactual
is a virtue. The laws used to describe
the inter?
supporting generalizations
actions between parts of mechanisms
and the laws which can be explained
can be of the most profound or banal sort. In
a
by mechanisms
explaining
we must
whose parts are interacting gravitationally
invoke a
rather deep law, while to explain mechanisms
like lawn mowers we most?
counterfactual
such as
ly invoke uninteresting
supporting generalizations,
mechanism
laws about
A more
it appeals
it seems
the behavior
of valves.
tomy use of Goodman's
serious objection
to an unanalyzed
notion of counterfactual
analysis
of laws is that
support. Furthermore,
that any analysis of counterfactuals
that we could give will
to causal notions. Given
that I intend to use
implicitly or explicitly
likely
appeal
to explain the nature of causation,
this appeal
my analysis of mechanisms
threatens to make my analysis
of causation
circular. In Section 4 I will
can be appealed
indicate how mechanisms
to in a non-circular manner
to
explain the notion of counterfactual
support.
The final part of (M) that I wish to clarify is the stipulation that the
laws governing
interactions between parts of mechanisms
laws. The stipulation
that the laws be causal is meant
be direct
causal
to exclude
lawful
which can be explained by common
causes. For instance,
generalizations
it is a lawful generalization
that night follows day, but certainly day does
not cause night. Rather,
the onset of day and of night are events which
are both caused by the earth's rotation. Relations
between
parts must be
otherwise
the parts could not be said
governed
by causal laws because
truly to interact.8
The further stipulation
that causal laws be direct can be illustrated by
the following
a system consisting
Consider
of a series of three
example:
or more gears of various
sizes. Given
information
about the number of
teeth on the gears, one can state a law Li describing
the rotation of the last
does not
gear as a function of the rotation of the first gear. Li, however,
describe an direct interaction between
the first and last gear. The interaction
is mediated
transmit the rotation from the first to the
by other parts which
last gear. By contrast, a law L2 describing
the rotation of the second gear
STUARTS. GLENNAN
56
as a function
stipulation
the behavior
of the first
is the sense
is direct. What
that a mechanism
we
are trying
is a collection
to capture by this
of parts, in which
stems from a series of local interactions
the aggregate
an
In
that
immediate
interaction
is local, I am not
parts.
saying
is
that
the
interaction
but
supposing
spatially local,
only that there are no
were
a
For
if
of
instance,
parts.
intervening
gravitation
genuine example
action at a distance,
the gravitational
interaction between
the earth and the
of
between
sun would
be direct, because
there would be no intervening
that the notion of directness
is relativized
the consequence
parts. This has
to a particular
1992, ch. 3).
(Glennan,
decomposition
The analysis
that I have
of mechanisms
a number
given resembles
of decompositional
for
Kauffinan's
artic?
strategies
explanation,
notably
ulation of parts explanation
Cummins'
and
functional
(Kauffman,
1970),
and Haugeland's
(Cummins,
1975,1980),
system?
analysis
morphological
several important
atic analysis
1978). There are, however,
(Haugeland,
of
these
authors
have
differences.
each
the role of these
First,
emphasized
a
within
for Cummins
science
strategies
special
(psychology
explanatory
and biology
for Kauffman),
whereas my account is intend?
and Haugeland,
I have
fundamental
ed to apply to all sciences
Second,
except
physics.
between
tried to illustrate the connection
decompositional
strategies and
most
I have
and
role of mechanisms.
the explanatory
Finally,
importantly,
(and will at the end of this paper) argued
and more generally,
causal explanations,
are
that these sorts of explanations
two events
that a relation between
is causal when and only when
events)
(other than fundamental
physical
in the appropriate way by a mechanism.
these events are connected
3.
can be analyzed
two simple mechanisms
in
a
to
the
The
first
(M).
system
regulate
example,
suggested by
account.
in a toilet tank, is clearly a mechanism
by anyone's
In this section
the manner
water
TWO SIMPLEMECHANISMS
level
Iwill
show how
to which
the parts interact
according
(excepting
gravity)
principles
a voltage switch, relies on
are "strictly mechanical".
The second example,
I will show that both
of
"non
mechanical"
different,
operation.
principles
The
of these systems may be analyzed
are mechanisms
inmy sense.
A. A Float
the lines of (M), and thus that they
Valve
a simple mechanism
to regulate
level in a
the water
a float valve.
It should be familiar to anyone who has
in accordance
with
the top of their toilet. Let us consider,
1 pictures
Figure
tank. It is called
ever
along
opened
MECHANISMSAND THE NATUREOF CAUSATION
57
Fill
Point
Water
Fig.
Source
1. A float
valve.
(M), what the behavior of this mechanism
is, what its parts are, and what
occur between
causal interactions
these parts to produce
the behavior
of
the mechanism.
The purpose of a float valve is to regulate the water level of
a tank, so it is natural (though not required) to single out the maintenance
of a certain water
in the tank (the fill point) as the behavior
of the
mechanism.
The operation
of the mechanism
is quite simple. A float is
attached to a lever which opens and closes an intake valve. When
the lever
level
is down
the intake valve is open, allowing pressurized water to fill the tank.
the lever is raised to a certain point, the intake valve closes, stopping
the flow of water. The float is heavy enough that in the absence of water
When
it will pull the lever down, opening
the intake valve. On the other hand,
it is sufficiently
that
the
buoyant
rising water level will force the float up,
water
the
intake
valve
when
reaches the fill point.
closing
In describing
number of parts:
a
the operation
of this mechanism
I have articulated
the tank, the valve,
water
the pressurized
source, the
lever and the float. I have also specified the ways
in which
these parts are
that is to say, I have described
the causal interactions between
connected;
one
one
the parts. If
could formulate precise laws describing
these
wished,
interactions. One would do this by specifying
of
the
parts, and
properties
to represent these laws.
equations
of the valve raises an important issue concerning
the
of mechanisms
In the above description
I have treat?
generally.
using mathematical
The description
description
ed the valve
as a kind of "black box"
switch. It could be replaced by any
into the tank only while
the lever is in
I have not specified how the valve itself works, only how
certain positions.
to the operation
as a whole.
it contributes
of the float valve mechanism
some more detail. According
The accompanying
to the
diagram suggests
a
the
valve
is
As
the
lever
is
the
is
low?
raised,
diagram,
piston.
piston
ered by a mechanical
Since
under
normal
conditions
linkage.
operating
device
which
allows water
to flow
STUART S. GLENNAN
58
SOURCE
R2
'out
in
Ri
Ground
Fig.
2.
A
voltage
switch.
laws, it is easy to treat it as a black
of its operation. The valve is itself
box, abstracting
a mechanism
within
the larger water-level
regulator mechanism.
Though
I have treated the valve as a simple part, one could equally well remove
the valve
behaves
according
away from
to simple
the details
to the piston,
to the valve, and replace it with references
the
is
the lever-piston
chamber,
linkage, etc. This kind of reductive analysis
not limited to the valve. One could also, for instance, give an explanation
the water and the float; One could,
of the details of the interactions between
so to speak, take the buoyancy mechanism
out of its black box. In general,
references
are inex?
the parts of a mechanism
to
it will be possible
in terms of any deeper physical mechanism,
plicable
take apart the parts and look at how they themselves work.
unless
the laws of interaction
between
B. A Voltage Switch
The float valve
by pushing
valve; water
is amechanism
each other. Water
not understand
ceases
in the ordinary sense. The parts all interact
pushes float; float pushes lever; lever closes
century scientists would
as
we
as well
do today, the qualita?
count as
to them. The float valve would
to push. Though
the fluid mechanics
were
seventeenth
well known
in Figure 2
switch illustrated
their
lights. The voltage
by
an
electric
rather
to
This
is
different
operates according
quite
principles.9
switch. There are, at least at the macrophysical
than amechanical
level, no
tive principles
a mechanism
it is easy to provide a mechanical
parts. Nevertheless,
moving
to the one provided
for the float valve.
this circuit analogous
analysis
of
MECHANISMSAND THE NATUREOF CAUSATION
V
59
SOURCE
?IIIIHII
?| Cutoff??
^
|| Region ?||
\
Saturation
A*
/.Region..
A A A A A A ..**
A
(vrF)
CESSATlliilil?ll
"?"a"?"?"a"a
fi. A
A A A A A
VYOFFVvON
Fig.
Already
3.
Input/output
behavior
for a voltage
switching
circuit.
in describing
the circuit in Figure 2 as a voltage switch, I have
a characterization
of its behavior. The switch has two terminals,
suggested
an input and an output. The behavior
this circuit as a switch is the variation
of importance
of input voltage
can be described
in characterizing
V{n with respect
to output voltage Vout. This behavior
quantitatively
by
=
For circuits of this type, the graph of this
giving a function Vout
f(Vin).
function has a distinctive
shape illustrated in Figure 3.When V{n is below a
certain voltage Voff, Vout is constant and equal to the voltage of the power
source VsourceF?r values of V{n below T^ff the transistor is said to be
in the cutoff region. Then, for a certain interval beyond T^off (the transient
region), Vout decreases
linearly as V{n increases. Finally,
approximately
as Vin increases beyond
the voltage Vqn? the output voltage
levels out at
a value
near
to 0, the collector-emitter
saturation voltage
(T/ce)sat? and
constant
for
values
of
If
V?n.
V{n < Voff,
approximately
larger
the switch is off, indicated by Vout = ^sourceIf Vin > ^on? the switch
is on, indicated by Vout = (Vce)sat ? 0.
remains
To analyze the mechanism
for the switching behavior, we
responsible
now articulate
the parts of the circuit. The central part is a junction
transistor (hereafter, simply transistor). The transistor has three terminals:
the base (left), the emitter (bottom) and the collector
(top). The relevant
of the transistor are given by the saturation voltage
properties
(Vce)sat
and a parameter ? that determines
the cutoff and saturation regions for
the transistor. In addition
there are two resistors,
the bias resistor with
must
resistance
and
the load resistor
with resistance ?2- There
is also a
a
rail
with
and
positive voltage
(top)
voltage Va
ground (bottom).
These might be terminals of a battery. Finally
there are input and output
as indicated in the circuit diagram.
terminals. These parts are connected
R\
source
STUART S. GLENNAN
60
The
circuit's
behavior
can be
summarized
by
Define Voff to be 0 and Von to be (R\Vsource/?Ri)-
two
simple
equations.
Then the equations
are:
(1)
Vin< V0?? =? (Vout= ^SOURCE) Switch off
(2)
Vin > V0N =* (Vout? 0)
switch on
a kind of current valve. When
is functionally
V?n < Voff
is
the
base
is
the
valve
closed
and no
(i.e., voltage
entering
negative),
>
current passes from the emitter to the collector. When
V{n
Von (i.e.,
The
circuit
the base is above a small positive
the valve is
value),
entering
current
to
and
from
the
emitter
the
collector.
When
passes
open
freely
current
<
is
<
the
valve
restricted
Vin
Voff
Von?
part way open, allowing
flow between
the emitter and the collector. Properties
of the load resistor
voltage
the voltage
for the output terminal in the on
(R2) and battery determine
the valve is open, these properties
also determine
and off states. When
the
current
the resistance of the bias resistor
output
Increasing
Ic(= Va/R2).
the valve opens.
the voltage Von at which
illustrates a number of important features of mechanisms
in accordance with (M). Most
and how they can be analyzed
importantly,
to mechanical
this circuit is susceptible
analysis even though it is not, in
as in the water
device. Additionally,
the engineer's
sense, a mechanical
R\
increases
This
circuit
are susceptible
to
themselves
regulator valve, the parts of the mechanism
to
It
is
mechanical
mechanical
(in my
give
explanations
analysis.
possible
of the resistors,
transistor, battery and conductors
sense) of the properties
this circuit
indicate why they have the properties
they do. Moreover,
itself be a part of larger mechanisms.
Indeed, the chief interest of
switching circuits is that they can be used as parts of larger electronic
logic
or control devices. Finally,
this circuit indicates how what the mechanism
which
can
I have given of the
is depends upon how you look at it. The description
Itwould also
electronics.
circuit has been largely in the terms of elementary
to give a description
of the system.
in terms of the microphysics
be possible
the
of the system in which
lead to a decomposition
This description would
parts were
be possible
lattices, or other such entities. Itwould also
electrons, molecular
for other purposes.
to consider this same circuit as amechanism
that produces
heat in the
so that the input current always falls into
bias resistor. Also, by arranging
the transient region, the same circuit can be used as a linear amplifier. The
has emphasized
the potential
logical
given, though electronic,
description
to cases where
of the circuit. Other descriptions,
appropriate
properties
We
could
for instance
input voltages
typically
linear behavior.10
consider
lie within
the mechanism
the transient
region, will
emphasize
its
MECHANISMS AND THE NATUREOF CAUSATION
61
to illustrate my analysis are both
them to illustrate
the point that
physical
no
a
on
nature
restriction
the
of
interactions
(M) places
priori
physical
between
is in no way limited to
parts. On the other hand, my analysis
mechanisms
that are physical
to apply to
in nature. It is meant
equally
The mechanisms
mechanisms.
that I have
I have
chosen
selected
and other higher level mechanisms.
I
biological,
psychological
this
because
the
of
the
is
emphasize
point
generality
analysis
key if it is to
for a theory of causation.11
provide a foundation
chemical,
4.
FUNDAMENTALAND MECHANICALLYEXPLICABLELAWS
of amechanism
such as the voltage switch can be described
in
terms of one or more laws (i.e., counterfactual
supporting generalizations)
like those given
in equations
of the
(1) and (2) above. A description
internal structure of the mechanism
this
I
behavior.
call
such
laws
explains
The behavior
mechanically
explicable.
There
is an important class of laws that are not mechanically
expli?
cable
laws. The essential
fundamental
feature of fundamental
laws is
that they are taken to represent facts about which no further explanation
is possible.12 While
it is difficult to define the notion of fundamental
law
and arguably impossible
to devise an adequate test to determine whether
or not a law is fundamental,
it is not hard to come up with a small body
are nearly unanimously
Exam?
regarded as fundamental.
include the law of universal
and
ples from classical
physics
gravitation
Maxwell's
In
this
status
is
to
accorded
equations.
contemporary
physics,
of laws which
to space-time
curvature or
equation
relating mass distribution
to Schr?dinger
for
equations
quantum mechanical
systems. There are also
are not fundamen?
many laws which, while
scientifically
quite significant,
tal: for example,
the ideal gas law, Hooke's
law, and laws of classical
Einstein's
genetics.
The claim
for which Iwill argue is that all laws are either
mechanically
or
tertium non datur. I will refer to this thesis
fundamental,
explicable
as the thesis of the mechanical
of non-fundamental
laws.
explicability
In arguing for this thesis, we must be careful to construe
it in such a
false nor trivial. A strong reading of it is
way that it is neither obviously
that every instance of a particular
lawlike regularity
is explained
by the
some
of
of
mechanism.
This
seem
would
operation
particular type
reading
to entail that laws describing
the behavior
of higher level mechanisms
would be type-reducible
to laws of a lower level theory. But a number of
widely
accepted
arguments
(Davidson,
1970; Fodor,
1974; Kitcher,
1984;
STUARTS. GLENNAN
62
Putnam,
1973; Wimsatt,
seldom possible.
A weaker
reading
1976)
suggest
that type reductions
of this sort are
of
the thesis of the mechanical
of
explicability
is that every instance of a non-fundamental
law
is explained
of some mechanism;
but it need not be the
by the behavior
case that the mechanisms
which explain the various
instances are all the
laws
non-fundamental
same, or even of the same kind. For a higher level law to be mechanically
itmust be realized by some lower-level mechanism,
but itmay
explicable,
This reading would
entail that laws describing
be multiply-realized.
the
are token-reducible
to lower-level
of higher level mechanisms
are
not
that
but
laws,
they
type-reducible.13
that there are higher level
The weak reading allows for the possibility
laws, every instance of which must be explained by a different mechanism,
behavior
perhaps even by a mechanism
the laws in question would
because
these mechanisms,
of a radically different kind. In such cases,
not genuinely
to
be explained
by reference
can
said
about
of
be
how the type
nothing
Such strongly irreducible laws
is produced by mechanisms.
mechanical
but would,
resist
like fundamental
laws,
explanation,
on
lower-level
mechanisms.
fundamental
laws, supervene
of non
the weaker reading, the thesis of the mechanical
explicability
lawful behavior
would,
unlike
On
laws is very plausible. The problem with the weaker reading is
that it seems to entail little more than the claim that higher-level
processes
on physical
insofar as I am committed
However,
processes.
supervene
about
the thesis says something
to a particular
analysis of mechanisms,
fundamental
be
in which
the way
occurs, and in this regard it might
supervenience
in
discussed
false. This point can be illustrated by the aether example
continuous
7. If there were a genuinely
2 and footnote
Section
aether,
we would
of
supervene on properties
say that electromagnetic
properties
the aether, but we would not be able
and magnetism
the laws of electricity
to say (without revising
(M))
were mechanically
explicable.
that
In
a claim about the relation of higher
is not primarily
addition,
but rather a claim about
level laws to fundamental
physical mechanisms,
If
laws to lower-level mechanisms
the relation of higher-level
generally.
the thesis
second
that explains Mendel's
one considers,
for instance, the mechanism
the
natural
in
assortment
of
law
of
law (the
genes
gametes),
independent
second law holds (when it
Mendel's
is cytological.
level of explanation
because
genes are often
same
on
the
chromosome),
away
created by choosing
"randomly"
holds)
pair. And
while
one could
on different chromosomes
(or far
and given how meiosis works, a gamete is
one chromosome
from each chromosome
located
look at the mechanisms
that explain
meiosis,
MECHANISMSAND THENATUREOF CAUSATION
that explain
the mechanisms
Mendel's
second
physical.
A key feature of mechanically
lematic way to understand
a generalization
about my
explicable
the counterfactuals
63
law are cytological,
not
laws is that there is an unprob
which they sustain. Consider
car starting when I turn the key. I am justified in
to
turn
the key, the car would start" because I know that
asserting
I also
which connects key-turning
with car-starting.
there is a mechanism
"If Iwere
know
the sorts of circumstances
in which
the counterfactual
would
to be false, namely breakdown
conditions
for the mechanism
it. I know for instance that my key-turning
would not
explains
out
turn
which
lead to
is too cold, or if there is no gas in the gas tank,
car-starting
I understand
the role of the battery and the gas in the ignition
because
can be understood
in this way
mechanism.
Counterfactual
generalizations
if the weather
without
world,
We
appealing
or the like.
to unanalyzed
notions
of cause,
propensity,
possible
are now
to partially address the worry raised in section
in a position
use
II about whether
the
of laws to describe
the interactions
of parts of
mechanisms
involves
tion are mechanically
character
supporting)
a circular appeal to causal notions. If the laws in ques?
then their lawlike (i.e., counterfactual
explicable,
can be explicated
to the further mech?
by reference
anisms which explain
these laws. There remains the difficulty
of under?
source
the
of
for
not offer
lawlikeness
I
fundamental
laws.
will
standing
a solution
to this last problem here, but I will argue in the final section
that the absence of an account of the lawlikeness
of fundamental
laws
a mechanical
does not undermine
of
laws
and
causal
analysis
higher-level
relations.
5.
I claimed
towards
a mechanical
theory
of causation
at the outset
of this paper that my theory of mechanisms
could
the foundation
for a theory of causation. Although
to spell out
provide
such a theory and defend it in any detail is beyond the scope of this paper,
I can indicate briefly how such a theory would
some
go, and suggest
of the theory.
consequences
Before outlining
such a theory, we should consider very generally
the
are
of
a
causation
should
solve.
There
stan?
number
of
problems any theory
dard ones: distinguishing
real from spurious correlations;
distinguishing
lawlike from accidental
real effects from
generalizations;
distinguishing
artifacts. These are all instances of what we can, using Humean
terminol?
ogy, call the connection-conjunction
problem. How does one distinguish
connections
from conjunctions?
Humean
seek to solve the
approaches
STUART S. GLENNAN
64
problem by giving
ties. Anti-Humean
necessity
nections.
(logical
I think
criteria
how
to some
typically appeal
approaches
or natural) which distinguishes
that both of these approaches
not discuss
but I will
difficulties,
to indicate
true from accidental
that distinguish
a mechanical
regulari?
further notion of
from con?
conjunctions
run into insurmountable
I want
here.14 Rather,
the connection-conjunction
these difficulties
theory
tackles
problem.
put, amechanical
suggests that two events
Roughly
theory of causation
con?
are causally
there is a mechanism
connected when and only when
a
a
case
most
in
is
the
works
clear
where
them.
How
such
necting
theory
switch
Take for instance the voltage
by a conditional.
3. The behavior of the voltage
switch can be
three
conditionals:
by
can be described
behavior
discussed
summarized
(1)
(2)
(4)
in Section
Vin < Vow
=> Vout = VsOURCE
Vin > Von =*Vout = (Vcd)sat ~ 0
Voff < Vin < Von => (Vce)sat < Vout < ^source
this behavior, we can say,
which underlies
there is a mechanism
than Voff to greater than
from
less
the
that
e.g.,
input voltage
increasing
to Vsource
a
causes
Von
change in the output voltage from (Vce)sat
the connection-conjunction
The chief virtue of the theory is that itmakes
can
one.
one
a
formulate
and confirm a theory that
If
scientific
problem
a
two
then one has produced
mechanism
events,
connecting
postulates
Because
evidence
are causally
from accidental
that dis?
The necessity
is to be understood
conjunctions
that these events
connected.
connections
tinguishes
as deriving from a underlying mechanism,
and nature
where the existence
The
mechani?
is open to empirical
of such a mechanism
investigation.
cal account
allows
connection-conjunction
to any metaphysical
There
is however
us to escape
with the
the regularity theory's difficulties
as
Hume did, reference
problem, while eschewing,
notion of necessity.
an obvious
to the mechanical
theory. Sooner
of a system into parts must come to an
laws. At this point we cannot point to
how do we
Since there is no mechanism,
limitation
or later the process of decomposition
end. This is the level of fundamental
any further or deeper mechanism.
between
explain the causal connection
events
at the level of fundamental
and I will not try to
theory offers
physics? The mechanical
to
it is sufficient
add anything about the problem here.15 For the moment,
is
in
relations
fundamental
causal
that
whatever
physics
explains
recognize
at
level.
causal
relations
which
that
higher
very different from
explains
us no answers,
There
presented.
are two potentially
The first of these
serious
alleges
to the theory that I have
objections
of causation
that
that any analysis
MECHANISMSAND THENATUREOF CAUSATION
65
on mechanisms
of the concept
since any explication
is circular,
of mechanism
requires the use of causal concepts. Of course one may
a system into parts and describing
a
mechanism
identify
by articulating
the behavior of the various parts; one may formulate statements describing
relies
these parts and show how the behavior
of the
from
the
derives
between
interactions
these
(the
effect)
system
mean
to
what
it
that
Is
does
these
interact?
it not
say
parts. However,
parts
some
to the mechanical
that
in
essential
the
of
theory
changes
properties
the interactions
between
as a whole
parts cause changes
This circularity
in the properties
of other parts?
is only apparent.
In describing
the mechanism
that
connects
the two events I have explained
how these events are causally
connected.
How
the parts are connected
is a different
I can
question.
this second question
another account of the
try to answer
by offering
mechanisms
which connect
them, but I need not give such an account to
between
the events. Indeed, such an account would
explain the connection
the causally
relevant features of the original explanation.16
only obscure
to the apparent circularity
The supposed circularity
is analogous
involved
in the recursive definitions
of sentences of predicate logic. A typical clause
of such a definition
'if p and q are sentences,
then (p & q) is
a string of symbols
also a sentence'. Whether
is a sentence depends upon
are sentences,
whether
certain other strings of symbols
but we are not
a
circular
because
sentences
the
in
used
the definition
definition,
offering
can themselves
to
be defined without
reference
the sentence
in whose
would
be
in giving account of how two
they are being used. Similarly,
are causally connected,
I refer to a mechanism
in turn refers
which
to causal relations, but these latter causal relations are different
(and more
one
am
than
I
relations
to
the
which
basic)
explain.
seeking
definition
events
cannot so easily be defeated. Even granting that
second objection
can progressively
at one level in terms of mecha?
explain interactions
nisms at the next, sooner or later, we are going to run out of levels and come
to interactions
laws. I grant without
governed
by fundamental
argument
The
we
that these fundamental
theory. But
interactions
interactions
cannot be explained by the mechanical
theory gives us no account of such
the fact that the mechanical
combined with the fact that any mechanism
depends ultimate?
on
there
at
causal
connections
the level of fundamental
ly
being
physics
that the mechanical
us
no
has
account
might lead us to believe
theory
given
of causation
at all. The objection
It is confessed,
that the utmost
of natural
phenomena,
effort
to a greater
... But
causes.
into a few general
their discovery-The
attempt
our ignorance
a little longer....
most
ismade
of human
eloquently
reason
is to reduce
and to resolve
simplicity,
as to the causes
of these
perfect
(Hume,
1777,
philosophy
pp. 30-31)
by Hume:
the principles,
productive
the many
effects
particular
we
in vain
should
causes,
of a natural
kind
only
staves
off
STUARTS. GLENNAN
66
Certainly
is correct
Hume
that there must
be some facts which
we cannot
to further more
explain by reference
must
Our explanations
this ultimate dependence
theory and adopt a regularity theory of causation.
why we are not forced to adopt a regularity
theory, we
up the mechanical
To understand
must
(or mechanisms).
general principles
at
somewhere.
The
issue is whether
stop
question
on unexplained
demands
that we give
regularities
look at how
it is that we
in fact evaluate
the truth of causal
claims.
to do this, I submit that the best way to
there are many ways
Although
to
evaluate such claims is
find the mechanism
for the supposed
responsible
causal connection.
If for instance, we want to show that smoking causes
the mechanism
cancer, the best way to do so would be to discover
by which
tar, nicotine,
etc.,
interact with
might provide overwhelming
between
and cancer,
smoking
mechanism
in question,
we
the body to produce cancerous
cells. We
to show the correlation
statistical evidence
but so long as we do not understand
the
can still wonder whether or not the correlation
that smoking causes cancer.17 Not only are regularities
insuffi?
are
as
cient to establish
causal connections,
well.
Once
unnecessary
they
we need not acquire additional
we have identified
the mechanism,
evi?
indicates
dence
for the regularities
it produces. Also,
or operations of the parts of the mechanism
further detail
about
the nature
are not relevant. The best way
to find out if it is a dead battery that is preventing my car from starting is
to use a voltmeter
to test the battery's charge. Once I have established
that
confirmed my hypothesis,
and
the battery has no charge, I have sufficiently
evidence. Although
the
taking apart the battery will provide no additional
two events may
for connecting
supervene
upon
responsible
on mechanically
and ultimately
lower-level mechanisms,
inexplica?
it is not these laws which make the causal
ble laws of fundamental
physics,
mechanism
other
true; rather, it is the structure
of its parts.
properties
claim
of the higher
level mechanism
and the
treats causa?
of a point of view which
Iwould
from
level
causation,
higher
physics differently
to sketch how the point of view of the mechanical
theory can
To illustrate
some of the benefits
tion in fundamental
like briefly
in the quantum theory. It is often said
shed light on an interpretive problem
as a predictive
successful
while
that the quantum
extraordinarily
theory,
to
cannot
that it predicts. This
be said
instrument,
explain the phenomena
predicament
correlations
illustrated
comes
produced
as follows.
in the case of the "unexplainable"
clearly
EPR
The problem may be
type experiments.18
by
to construct a device which
shoots a
It is possible
out most
to distant targets. These particles
in opposite
directions
pair of particles
can be prepared
in such a way that, upon hitting these targets they will
deflect in one of two directions,
up or down. It is not possible
using this
MECHANISMS AND THE NATUREOF CAUSATION
67
to determine
in advance which direction
technique
preparation
they will
mechanics
and
that if
confirms
go. However,
quantum
predicts
experiment
one particle deflects up then the other particle will deflect down and vice
versa.
seem
There
to be two explanations
which might account for this corre?
there might be some signal sent from one target to the other.
lation. First,
This possibility is ruled out (if relativity theory isright) by placing the tar?
gets so far apart that any interactions
than the speed of light. Alternatively,
require signals to travel faster
one might
think that the preparation
into a certain state which causes them
would
of the particle pair puts the particles
or the other when
to go in one direction
they reach the target. Surpris?
results (so called no-hidden-variable-theory
ingly, however, mathematical
results) indicate that there can be no such state.
This
result
is generally
stand. It indicates
correlations
an indirect
considered
with
(consistently
events where
between
to be very strange and hard to under?
that there are
evidence)
experimental
neither
a direct
causal
connection
nor
via a common-cause
can possibly
account for that
I think that the analysis of causation
correlation.
that I have offered shows
is so puzzling
about the cor?
why we should not be so surprised. What
relation in question
is that there is no mechanism
which
could possibly
connect the events occurring
at the two targets and that there is no mech?
connection
anism which
could possibly
connect
them each to some
cause. However,
if one believes
that quantum mechanical
the most fundamental
then one does not believe
physics,
third common
laws describe
is a
no
mechanism
if
And
there
is
rea?
such
what
anyway.
mechanism,
deeper
son is there to believe that distal events should or should not be correlated?
Our uneasiness
derives in part because we expect that the laws describing
this quantum mechanical
similar to those
system should have properties
of mechanically
laws; but there is no reason to have such an
explicable
It is an artifact of our belief
expectation.
that there
that there is something
behind
the
regularities.
The mechanical
theory of causation
rejects a wide-spread
assumption
about the nature of causation.
I think that it is generally assumed that what?
ever causal connections
to do with the
are, they ultimately have something
most
fundamental
the more
physics,
further we
from
causal
The closer we are to fundamental
processes.
physical
our statements
are about the true causes of
things; the
into the higher-level
the more we move
sciences,
away
stray
statements
however,
assumption,
causes
this assumption
damental
physical
and toward mere
is what makes
Hume's
This
generalizations.
so
skepticism
devastating. On
empirical
are the ultimate metaphysical
events together. Hume provides
glue which
a convincing
holds
fun?
argument
68
STUART
S. GLENNAN
that we
can have no knowledge
of this glue, and that talk of such glue may
to these difficulties
be unintelligible.
The solution
is to reverse the
initial assumption.
Causal statements are typically statements about events
even
and mechanisms
regulated by mechanisms,
ties. Only when we talk about interactions
does
causal
To what
higher level enti?
fundamental
laws
by
governed
talk become
problematic.
have we have solved Hume's
extent
problem? To what degree
that binds together causally con?
the level of fundamental
still
problem
physics, Hume's
have we uncovered
nected
are complex,
the secret connexion
At
events?
can observe
but we cannot offer an expla?
regularities,
obtain. It is not good enough to say that in
nation of why those regularities
are
there
for there are still questions
about which
just
regularities,
physics
are
lawful
and
causal.
the
difficulties
that
remain, we
regularities
Despite
remains. We
certain
one. In the case of
is not a universal
that Hume's
problem
we
can
between
connections
and conjunc?
laws,
distinguish
higher-level
can
we
understand
the
mechanisms
which
because
tions,
produce higher
is not so secret after all.
level regularities. Very often, the connexion
have
shown
NOTES
*
I would like to thank Erich Reck, Mike Price, Bill Wimsatt, Ron McClamrock, Dan
Howard
Garber,
Hume.
him
are
unknowable?
interpretation,
Strawson
(1989).
purposes
2
I should
the hood
under
3
For
there
Whatever
which
experts
a discussion
regularities,
Hume's
interpretation
taken as leading
of Hume,
of
of
interpretation
lead
skepticism
that these powers
or only
to argue
century
empiricists
For a defense
is not decisive.
the correct
the
for
the
latter
it is sufficient
former
view,
see
for my
or which
is open
and Corpuscularism
to empirical
investigation.
in the seventeenth
century
see
2).
or teleological
it makes
constraints,
very few restrictions
etiological
to describe
as a mechanism.
For instance,
it is quite possible
my belt
a mechanism
such as this is not worthy
bullets.
Generally
stopping
as a mechanism
for
of
but we
investigation,
death
untimely
understand
of Mechanism
ignores
could count
because
not seem so silly.
5
here
I do not mean
can imagine
contexts
where
a bullet
off of my
ricocheted
it would
be.
If I was
buckle
then
this mechanism
saved
from
an
would
I do, however,
of object.
to give a definitive
of the notion
analysis
to be
it seems
whatever
term is plausible,
because
are,
objects
of contexts.
that they can exist in a variety
that my
important
the proper
Does
to the regularity
is often
theory of causation.
argument
to
I
not
of what
is under
need
have
do
that
any knowledge
personally
emphasize
a causal claim.
that there is something
that I believe
It is sufficient
in order to make
Glennan(1992,ch.
4
4 Since
(M)
think
evidence
textual
about
question:
tend
that Hume's
the hood
on what
twentieth
on earlier
and for comments
discussions
claims
the following
ignoring
are no powers
behind
Although
the
to make
introduction
I am
In particular,
to believe
that
for fruitful
and Ken Waters
Stein
drafts of this paper.
1
in this
I do not wish
use
of
the
MECHANISMS AND THE NATUREOF CAUSATION 69
I would
like
entities which
is that there are certain
this stipulation
with
One problem
sense properties.
are in a natural
beliefs
and
For instance,
as objects which
to consider
as properties,
to allow
are often described
but I want
states generally)
desires
(or mental
are parts. There
that prevents
is nothing,
entities
however,
as objects
under
under some descriptions
and as properties
are properties
under
one description
of our brains, while
beliefs
and desires
others. Under
and desires are themselves
is right), beliefs
another description
(if some brand of cognitivism
have
various
which
computational
properties.
objects
6
of
the requirement
In the case of a physical
like the electromagnetic
field,
"system"
I have used the
that the parts be discrete.
is roughly
the requirement
isolability
empirical
such
in which
for mechanisms
us from
such
viewing
entities
term because
in cases where
parts are not
general
of discreteness
amounted.
be clear to what a requirement
more
localizable
spatially
it would
not
7
The possibility that the electromagnetic field could be explained in terms of properties of
aether
an explanation
aether would
about (M). A detectable
provide
question
to say that aether
it then be correct
the electromagnetic
field, but would
waves?
If (M) is correct,
then it would
that transmits
electromagnetic
a further
raises
of
of properties
is the mechanism
if it were possible
to decompose
to call the aether a mechanism
it into
only be appropriate
a
turn
out
to
that
aether
would
be
continuous
But
it
is
the
discrete
parts.
genuinely
possible
so no such decomposition
would
that
and if this were
be available.
medium,
Supposing
or not
a detectable
there would
be a further empirical
whether
there were
aether,
question
the aether was
of discrete
composed
particles.
of a genuinely
continuous
aether raises a question
the possibility
in such a way
that all mechanisms
(M). (M) defines mechanisms
In short,
erality of
of discrete
(in the sense
"continuous
have
of decomposible)
If we wished
mechanism".
to amend
the definition
parts,
to count
to allow
(M)
but a continuous
the aether
about the gen?
are collections
for "continuous"
be a sort of
aether would
as a mechanism,
mechanisms
we would
then
a single
having
emendation.
our best physical
theories
do not demand
continuous
such
part. Currently,
8
one must
an adequate
to work,
to distinguish
If this account
is ultimately
have
way
to solving
between
these two kinds
of laws. One of the most
this
promising
approaches
use
as
is
of
the
statistical
known
off"
(see e.g., Salmon,
problem
by
relationship
"screening
For
1984).
a discussion
of
is taken directly
McCausland,
1978). See ?9.4 and
10
It is the higher
level description
chosen
the context
by considering
what
aspects
of the lower-level
point seeMcClamrock
11
Examples
contains
from
a case
of
the limitations
this approach
together
with
alternatives,
see
5).
Glennan(1992,ch.
9
This
example
an undergraduate
text
electronics
(Calvert
and
the circuit
(e.g., whether
in which
the circuit occurs,
behavior
are significant
or a switch),
is an amplifier
us to determine
that allows
as opposed
to noise.
For
a similar
(1995) Chapter 1.
sciences
study
from
?14.2.
of
other
than physics
two models
of vowel
are discussed
normalization
in Glennan
mechanisms
6
Chapter
that have been
(1992).
developed
by cognitive
psychologists.
12
I am presuming
that these laws are laws of physics.
13
It would
to spell out the relationship
take a fuller exposition
between
different
tations of mechanical
and various
As framed
types of reducibility.
explicability
interpre?
by Fodor
terms and
are theses about the reducibility
of theoretical
type and token reducibility
to theoretical
terms and laws of another. While
of one theory
there is an analogous
reduction
relations
between
laws and the mechanisms
which
realize
them, some work must
to show how
be done
of laws and theoretical
terms is related
to type
type-reducibility
(1974),
laws
reducibility
of mechanisms.
STUARTS. GLENNAN
70
some
1 suggest
an excellent
reasons
in Chapter
8 of Glennan
See
(1992).
also
Salmon
for
(1984)
cannot
theories
solve the connection-conjunction
regularity
an account
In
6
book
and
Salmon
that
of causation
that
5,
9),
proposes
problem.
(Chapters
to address
is meant
this problem
and that in certain ways
parallels my own account.
Space
so I can only mention
one problem
does not permit me to discuss
Salmon's
theory in detail,
discussion
of why
that his theory is incomplete.
Salmon's
with distinguish?
suggests
theory is concerned
are the sorts
what
causal
from
he
calls
processes
ing
pseudo-processes".
Pseudo-processes
of things which
non-causal
but
lawlike
Salmon's
criterion
for distin?
regularities.
produce
which
can transmit "marks".
is that causal processes
these processes
has
Salmon
not explained
transmit marks where
why causal processes
pseudo-processes
true difference
can only be
between
causal processes
and pseudoprocesses
between
guishing
unfortunately
do not. The
in the mechanisms
the differences
them.
view, by considering
underlying
to explicate
in a way
causal
relations
that dovetails
with
fundamental
the
account
in Glennan
(1995).
in my
explained,
151 discuss
how
mechanical
16
Kitcher
(1984)
17
A similar point
(1982).
causal
18
For
from
theory of causation
of
correlations
and artifactual
a discussion
of EPR
thesis R3.
a causal relationship
between
for attributing
accounts
of causation
this that regularity
sufficient
conclude
They
properties).
The mechanical
of his
of evolutionary
by Sober and Lewontin
biology
events
of actual or dispositional
between
regularities
that the existence
is not
in his discussion
observation
in the case
has been made
argue
They
(or properties)
a similar
makes
I have presented
this sort.
correlations
see,
e.g.,
(or
are
inadequate.
to distinguish
between
one
allows
events
those
(1989).
Shimony
REFERENCES
and M.
J. M.
Calvert,
A.
H. McCausland:
R.
F. Mandl,
Series,
Physics
Chichester.
'Functional
Cummins,
Robert:
1975,
Cummins,
Robert:
1980, The Nature
Davidson,
Donald:
1970,
'Mental
Abaris
Fodor,
Books,
New
Glennan,
of Chicago.
University
Stuart S.: 1995,
Glennan,
Butler
David:
Sons,
72,741-765.
of Philosophy
MIT
Explanation,
and J.W. Swanson
Press,
Cambridge.
(eds.), Experience
Amherst.
la Lumi?re,
or The Disunity
and
Models
'A Two-Tiered
1777,
edited
and translated
of Sciences
Causation,
of Causation',
Theory
by Michael
as aWorking
Ph.D.
Hypo?
the
Dissertation,
manuscript,
unpublished
Press,
University
Stuart:
Kauffman,
for Them',
of Science,
PSA
reprinted
1975.
Oxford,
1970,
from
the
Human
1777
Understanding
edition,
1970, Vol.
Vm,
and
D. Reidel,
Dordrecht.
concerning
3rd ed., P. H. Nidditch,
in Biology
of Parts Explanation
Studies
and R. S. Cohen
(eds.), Boston
'Articulation
in R. C. Buck
and
Behavioral
of Cognitivism',
and Plausibility
concerning
Enquiries
of Morals,
Principles
Search
Press,
de
&
University
'The Nature
John:
1978,
Haugeland,
215-226.
Sciences
Brain
1,
Hume,
of The Manchester
John Wiley
1979.
York,
Sciences,
1974,
'Special
28, 97-115.
Synthese
S.: 1992, Mechanisms,
Stuart
(eds.),
Journal
Analysis',
Jerry A:
thesis',
X
Vol.
J. Sandiford
of Psychological
in L. Foster
Events',
of Massachusetts
and Theory, University
ou Trait?
Le
Ren?:
Monde,
1664,
Descartes,
S. Mahoney,
Electronics
1978,
and D.
J. Ellison
and
the
Oxford
the Rational
in the Philosophy
MECHANISMSAND THE NATUREOF CAUSATION 71
Kitcher,
'1953
1984,
Philip:
335-74.
93,
R.:
and All
A Tale
That.
1995, Existential
Cognition:
Press, Chicago.
sity of Chicago
Ernest:
1961, The Structure
Nagel,
of Science,
McClamrock,
Putnam,
Hilary:
Harcourt,
1984, Scientific
Explanation
Wesley:
Princeton
Press, Princeton.
University
Abner:
(ed.), The New
Sober,
Elliott,
Philosophy
Strawson,
1989,
Brace
Foundations
'Conceptual
in the World,
Jovanovich,
of Psychology',
and
the Causal
of Quantum
William
C:
Univer?
Inc., New
Cognition
Structure
of
York.
2,131-146.
the World,
in Paul Davies
Mechanics',
Press, Cambridge.
Physics,
Cambridge
University
and Richard
C. Lewontin:
Cause
1982,
'Artifact,
of Science
Galen:
1989,
Review
Philosophical
Minds
Computational
Salmon,
Shimony,
Sciences',
and the Nature
'Reduetionism
1973,
of Two
and Genie
Selection',
49,157-80.
The Secret
Clarendon
Connexion,
Press,
Oxford.
the Logical
of Function
Structure
Statements',
'Teleology
inHistory
Studies
and Philosophy
3, 1-80.
of Science
William
C: 1976,
Levels
of Organization,
and the Mind-Body
Wimsatt,
'Reductionism,
Wimsatt,
Problem',
Brain:
in G. G. Globus,
A Scientific
and
1972,
G. Maxwell
and Philosophical
and
Inquiry,
Manuscript submitted October 10, 1994
Final
version
received
July
13,
1995
Dept. of Philosophy and Religious Studies
Butler
4600
University
Sunset Ave.
Indianapolis, IN 46220
U.S.A.
I. Savodnik
Plenum,
(eds.),
New
Consciousness
York.
and
the