WHAT ARE CAUSAL POWERS
Andrea Raimondi
University of Nottingham
http://about.me/Raimondiand
Abstract
"Metaphysics of powers offer an alternative approach to the
problem of causation. It is argued that this approach, causal
dispositionalism, is explanatory of the behaviour of biological
systems and artefact in terms of their causal production. This
behaviour is a function of selection between natural
possibilities that powers support and constrain."
1. Dispositional Properties
According to dispositionalism, causation is produced by the exercise of
causal powers. The reason why dispositional properties are often
called powers is to highlight their causal role.
Dispositions inhere in the object of dispositional ascription. The causal
in causal powers is the fact that their exercise is productive of the
behaviour of things.
Dispositions are not mere potentialities. Their manifestations do not
depend on the presence of an active stimulus. To say that
something is soluble is not to think that the property is instantiated
only when the dissolving occurs (Mumford 1998).
Dispositions are active, but they produce the effect by composing
together with other dispositions. Causation as mutual
manifestation partnership explains the effect as the change in
powers when they team up. This starts a causal process that is
diachronical, with which we can interfere and that have as effect a
modification of the causal scenario.
2. Causal production
The exercise of dispositions represents causal production. For
dispositionalism individuals have their own causal powers and any
effects exhibited are the manifestation of those powers. But
objects possess dispositional properties even if those are not
manifested. To say that dispositional property is a property that can
exist unmanifested means that it points to hidden potentials
of objects.
A dispositional theory of causation sees discovery in the sciences as the
exploitation of causal powers, and achievements in technology as
the ability to use objects' hidden dispositional properties to build
systems specifically designed to support a constrained set of
possibilities.
Causation as the passing around of powers depicts hidden potential as a
disposition for the instantiation of another possible causal
property. That which is soluble has the potential to become
dissolved (Mumford 2009).
Causation explains the activity of individual objects in virtue of their
dispositional properties. Most of the complex biological
interactions that dispositionalism claims to explain involve causal
interaction.
(a) Not all the causal interactions are also functional (in the sense
explained below).
Then how can a functional account be given of dispositions?
3. Dispositionality as selection function
[Note: 'function' here, is used not in the teleological sense, in which
biological organs have functions, but in the mathematical sense in which
a function given an argument selects values from a range of possible
values.]
The idea of a selection function is meant to explain that when powers
are exercised a subset of realm of possibilities is selected, favouring
some among others. Changes in dispositional properties are explained
in terms of selection from a range of natural possibilities
(Mumford&Anjum 2011).
The exercise of powers provides the object with abilities to interact
causally with the world, linking sets of possible changes. The modal space
available to the object is marked by a set of possible causal links
between natural possibilities (Sloman 1996).
Dispositional ascription allows causal explanations of behaviour of
natural things. Since dispositionality selects natural possibility, not
logical possibility, when powers are exercised we often know what to
expect. But dispositionality acts between pure contingency and
pure necessity.
A disposition only tends toward its manifestation, but does not necessitate
the effect. We make sense of ascribing a dispositional property to
an object without implying that the manifestation is necessitated
3.1 Compositional pluralism and directness
The same disposition can be manifested differently in response to the
presence or absence of other powers at work. Compositional
pluralism is the claim that there are pluralities of ways in which
powers can compose to produce an effect. When they team up
they alter each other's contributions to the causal outcome
(Mumford&Anjum 2011).
That a vase is fragile means there are possible ways in which the vase
can be damaged: it can be struck by a hammer, pushed to the
ground or smashed against the wall. There are also possible ways
in which the vase can tend to break: it can break into a few pieces, or
tiny fragments, or be burned to dust by a laser. Also a piece of metal
could be fragile. However for the fragility of metal to be manifested
requires that other causal powers are in place. For instance, diminish
the temperature of the object beyond a certain threshold and it will
become as fragile as a vase.
Dispositionality explains objects' modal facts that are effects of the
powers' control over potentialities. Powers act as a whole, at
different levels of reality. A kiss may cause embarrassment, as well as
energy transfer between bodies. A cube of sugar can be disposed to
dissolve in water, as well as sweetening the solution.
(b) Which of these types of directness can be considered functional?
(i.e. selecting from a set of possibilities.)
3.2 Getting functional
Functional Dispositionalism assumes that things in nature generate,
maintain and develop their own modal space and powers are
causal in that they constrain possible changes as causation occurs.
An object's dispositions depend on what natural possibilities are at hand;
and which outcome is brought about depends on which functional role (which
ability to select among possibilities) is instantiated. It is not obvious
what it is for a disposition to be a function in this sense.
A common assumption of dispositional ascription and functional
ascription is that both endorse a function/accident distinction.
Within this distinction the sweetened solution is an accidental effect
of the functional power of the solubility of sugar (Wright 1976).
"Dispositional" and "functional" are ascriptions that are always relative to
a choice of explanandum (what is to be explained) (Wright 1973).
(c) Then, is the claim that dispositional ascriptions are functional
ascriptions informative?
When we ascribe a disposition we are giving a functional
characterization of the property, according to what potentialities
are supported in various causal contexts. For something to be elastic
means to have a dispositional properties that cause it to stretch
when pulled and to shrink when the pull is removed. We functionally
characterize this disposition in terms of elasticity.
Dispositional ascriptions are explanatory when they indicate what
potency is present in the object of ascription. The functional
characterization of this property does not exclude the same
disposition from manifesting other effects accidentally.
Dispositionality as selection function implies possible changes in the
composition of powers. To ascribe a disposition to an object is to say
something about what the object can do, within its modal space, not how it
organizes it. To say that A and B mutually manifest C is not to say how A
and B compose C.
The dispositionalist claim is informative in that it suggests that dispositions
are particular kinds of functions (selections) (Mumford 1998).
If an object exhibits a function it is because the object has the
ability to do that. And to have ability is to have a disposition.
Nonetheless a dispositional ascription just specifies that a causal
contribution has a functional (selective) role, but leaves open how the
contribution is integrated when other powers contribute to realizing the
function.
4. Dispositionality and Complexity
(d) The realization of a function requires more than possession of a disposition.
The modality of the system is represented as a selection function that
acts on various dispositions whose manifestations work toward a
common end-state.
It is because a disposition is a particular kind of function that we can
admit the production of non-functional changes. For instance, the
appearance of an adaptive trait in an organism is strongly coupled
with the manifestation of non-adaptive traits. However those traits
might reveal themselves functional during an organism's development
(Nagel 1979).
For powers to instantiate a function they must be organized
appropriately. Only when causal powers of many components are
brought together in the right arrangement are hidden
potentialities supported, e.g. a bridge.
When we pull ends of a climbing rope apart, that could provide a
new pathway to an end-state. There could be knots forming that
affect how the rope can be pulled. Its wetness can affect how the
rope curls.
A wire has a disposition to conduct electricity. But cooling down a piece of
metal and same dispositions manifest superconductivity, together
with the ability to store energy. With appropriate causal factor it
can dispose toward making light.
Where processes develop, different constraints on possibilities might
emerge and affect the paths to the end-state. Those constraints are
better understood as changes in complexity, affecting the way
dispositions can compose together.
In complex systems functions always involve dynamically varying causal
inputs that are selected toward a casual output, each of those
modulates each other effect.
The ways components are organized have effects upon the selection
function, causing a change in complexity, both compositional and
dynamical. Functions in systems are involved with possible
interactions that change possibility between parts.
We can join two wires in parallel and their voltage is constrained to be
the same. When joined in series, the same happens to current. In both
cases, the disposition ascribed to the system could not be reduced
to the sum of the powers of the components.
Two wires coupled in a diode compose a complex object whose
functional characterization cannot be reduced to the sum of
functional characterization of component properties.
Functional dispositionalism can accept physicalism without implying
reductionism since powers act at different levels of complexity.
4.1 Adaptive Emergence
(e) Exercise of powers regulates the selection of naturally possible
outcomes with respect to interference in the causal ecosystem in
which the system behaves.
Functional systems are responsive to causal ecosystem in which they
behave. A functional account of dispositions can help investigate
emergent abilities of biological systems in terms of adaptive
response to environmental influence.
Organization only disposes toward the end-state since systems
behaviour is brought about by different dispositions working
together. Dispositional ascription instantiate more than one
functional role concurrently.
The adapting feature of powers composition can represent a step
toward the explanation of emergent change in complexity: evolved
complexity (Mitchell 2003). This complex feature of biological
systems can be interpret as incremental constrain over the modal
space generated by causal development.
References
Mumford, S. & Anjum, R. L., (2011). Getting Causes from Powers. OUP Oxford.
Mumford, S., (1998). Dispositions. Oxford University Press.
--- (2009). Passing Powers Around. The Monist 92 (1):94-111.
Mitchell, S., (2003). Biological Complexity and Integrative Pluralism. Cambridge Univ Pr.
Nagel, E., (1979). Teleology Revisited and Other Essays in the Philosophy and
History of Science. Columbia University Press.
Sloman, A., (1996) Actual possibilities. In Principle of Knowledge Representation
and Reasoning: Proceedings of the Fifth International Conference (KR'96).
Morgan Kaufmann Publishers.
Wright, L., (1973). Functions. Philosophical Review 82 (2):139-168.
---(1976). Teleological Explanations: An Etiological Analysis of Goals and
Functions. University of California Press.