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"turtoni" |
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18 Nov 2007 01:20:56 AM |
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Aristotle on Causality |
Introduction
Aristotle was not the first person to engage in a causal investigation
of the world around us. From the very beginning, and independently of
Aristotle, the investigation of the natural world consisted in the
search for the relevant causes of a variety of natural phenomena. From
the Phaedo, for example, we learn that the so-called "inquiry into
nature" consisted in a search for "the causes of each thing; why each
thing comes into existence, why it goes out of existence, why it
exists" (96 a 6-10). In this tradition of investigation, the search
for causes was a search for answers to the question "why?". Both in
the Physics and in the Metaphysics Aristotle places himself in direct
continuity with this tradition. At the beginning of the Metaphysics
Aristotle offers a concise review of the results reached by his
predecessors (Metaph. I 3-7). From this review we learn that all his
predecessors were engaged in an investigation that eventuated in
knowledge of one or more of the following causes: material, formal,
efficient and final cause. However, Aristotle makes it very clear that
all his predecessors merely touched upon these causes (Metaph. 988 a
22-23; but see also 985 a 10-14 and 993 a 13-15). That is to say, they
did not engage in their causal investigation with a firm grasp of
these four causes. They lacked a complete understanding of the range
of possible causes and their systematic interrelations. Put
differently, and more boldly, their use of causality was not supported
by an adequate theory of causality. According to Aristotle, this
explains why their investigation, even when it resulted in important
insights, was not entirely successful.
This insistence on the doctrine of the four causes as an indispensable
tool for a successful investigation of the world around us explains
why Aristotle provides his reader with a general account of the four
causes. This general account is found, in almost the same words, in
Physics II 3 and Metaphysics V 2.
The Four Causes
In the Posterior Analytics, Aristotle places the following crucial
condition on proper knowledge: we think we have knowledge of a thing
only when we have grasped its cause (APost. 71 b 9-11. Cf. APost. 94 a
20). That proper knowledge is knowledge of the cause is repeated in
the Physics: we think we do not have knowledge of a thing until we
have grasped its why, that is to say, its cause (Phys. 194 b 17-20).
Since Aristotle obviously conceives of a causal investigation as the
search for an answer to the question "why?", and a why-question is a
request for an explanation, it can be useful to think of a cause as a
certain type of explanation. (My hesitation is ultimately due to the
fact that not all why-questions are requests for an explanation that
identifies a cause, let alone a cause in the particular sense
envisioned by Aristotle.)
In Physics II 3 and Metaphysics V 2 Aristotle offers his general
account of the four causes. This account is general in the sense that
it applies to everything that requires an explanation, including
artistic production and human action. Here Aristotle recognizes four
types of things that can be given in answer to a why-question:
The material cause: "that out of which", e.g., the bronze of a
statue.
The formal cause: "the form", "the account of what-it-is-to-be", e.g.,
the shape of a statue.
The efficient cause: "the primary source of the change or rest", e.g.,
the artisan, the art of bronze-casting the statue, the man who gives
advice, the father of the child.
The final cause: "the end, that for the sake of which a thing is
done", e.g., health is the end of walking, losing weight, purging,
drugs, and surgical tools.
All the four (types of) causes may enter in the explanation of
something. Consider the production of an artifact like a bronze
statue. The bronze enters in the explanation of the production of the
statue as the material cause. Note that the bronze is not only the
material out of which the statue is made; it is also the subject of
change, that is, the thing that undergoes the change and results in a
statue. The bronze is melted and poured in a wax cast in order to
acquire a new shape, the shape of the statue. This shape enters in the
explanation of the production of the statue as the formal cause.
However, an adequate explanation of the production of a statue
requires also a reference to the efficient cause or the principle that
produces the statue. For Aristotle, this principle is the art of
bronze-casting the statue (Phys. 195 a 6-8. Cf. Metaph. 1013 b 6-9).
This is mildly surprising and requires a few words of elaboration.
There is no doubt that the art of bronze-casting resides in an
individual artisan who is responsible for the production of the
statue. But, according to Aristotle, all the artisan does in the
production of the statue is the manifestation of specific knowledge.
This knowledge, not the artisan who has mastered it, is the salient
explanatory factor that one should pick as the most accurate
specification of the efficient cause (Phys. 195 b 21-25). By picking
the art, not the artisan, Aristotle is not just trying to provide an
explanation of the production of the statue that is not dependent upon
the desires, beliefs and intentions of the individual artisan; he is
trying to offer an entirely different type of explanation; an
explanation that does not make a reference, implicit or explicit, to
these desires, beliefs and intentions. More directly, the art of
bronze-casting the statue enters in the explanation as the efficient
cause because it helps us to understand what it takes to produce the
statue; that is to say, what steps are required to produce the statue.
But can an explanation of this type be given without a reference to
the final outcome of the production, the statue? The answer is
emphatically "no". A wax cast is made for producing the statue. The
bronze is melted and poured in the wax cast. Both the prior and the
subsequent stage are for the sake of a certain end, the production of
the statue. Clearly the statue enters in the explanation of each step
of the artistic production as the final cause or that for the sake of
which everything is done.
In thinking about the four causes, we have come to understand that
Aristotle offers a teleological explanation of the production of a
bronze statue; that is to say, an explanation that makes a reference
to the telos or end of the process. Moreover, a teleological
explanation of the type sketched above does not crucially depend upon
the application of psychological concepts such as desires, beliefs and
intentions. This is important because artistic production provides
Aristotle with a teleological model for the study of natural
processes, whose explanation does not involve beliefs, desires,
intentions or anything of this sort. Some have contended that
Aristotle explains natural process on the basis of an inappropriately
psychological teleological model; that is to say, a teleological model
that involves a purposive agent who is somehow sensitive to the end.
This objection can be met if the artistic model is understood in non-
psychological terms. In other words, Aristotle does not psychologize
nature because his study of the natural world is based on a
teleological model that is consciously free from psychological
factors. (For further information on the role that artistic production
plays in developing an explanatory model for the study of nature, see
Broadie 1987, pp. 35-50.)
One final clarification is needed. By insisting on the art of bronze-
casting as the most accurate efficient cause of the production of the
statue, Aristotle does not mean to preclude an appeal to the beliefs
and desires of the individual artisan. There are cases where the
individual realization of the art obviously enters in the explanation
of the bronze statue. For example, one may be interested in a
particular bronze statue because that statue is the great achievement
of an artisan who has not only mastered the art but has also applied
it with a distinctive style. In this case it is perfectly appropriate
to make reference to the beliefs and desires of the artisan. Aristotle
seems to make room for this case when he says that we should look "for
general causes of general things and for particular causes of
particular things" (Phys. 195 a 25-26). Note, however, that the
idiosyncrasies that may be important in studying a particular bronze
statue as the great achievement of an individual artisan may be
extraneous to a more central (and more interesting) case. To
understand why let us focus on the study of nature. When the student
of nature is concerned with the explanation of a natural phenomenon
like the formation of sharp teeth in the front and broad molars in the
back of the mouth, the student of nature is concerned with what is
typical about that phenomenon. In other words, the student of nature
is expected to provide an explanation of why certain animals typically
have a certain dental arrangement. We shall return to this example in
due course. For the time being, however, it is important to emphasize
this important feature of Aristotle's explanatory project; a feature
that we must keep in mind in trying to understand his theory of
causality. This theory has in fact been developed primarily (but not
exclusively) for the study of nature.
The Four Causes in the Science of Nature
In the Physics Aristotle builds on his general account of the four
causes by developing explanatory principles that are specific to the
study of nature. Here Aristotle insists that all four causes are
involved in the explanation of natural phenomena, and that the job of
"the student of nature is to bring the why-question back to them all
in the way appropriate to the science of nature" (Phys. 198 a 21-23).
The best way to understand this methodological recommendation is the
following: the science of nature is concerned with natural bodies
insofar as they are subject to change, and the job of the student of
nature is to provide the explanation of their natural change. The
factors that are involved in the explanation of natural change turn
out to be matter, form, that which produces the change, and the end of
this change. Note that Aristotle does not say that all four
explanatory factors are involved in the explanation of each and every
instance of natural change. Rather, he says that an adequate
explanation of natural change may involve a reference to all of them.
Aristotle goes on by adding a specification on his doctrine of the
four causes: the form and the end often coincide, and they are
formally the same as that which produces the change (Phys. 198 a
23-26). This is one of the several times where Aristotle offers the
slogan "it takes a man to generate a man" (for example, Phys. 194 b
13; Metaph. 1032 a 25, 1033 b 32, 1049 b 25, 1070 a 8, 1092 a 16).
This slogan is designed to point at the fundamental fact that the
generation of a man can be understood only in the light of the end of
the process; that is to say, the fully developed man. What a fully
developed man is is specified in terms of the form of a man, and this
form is realized in its full development at the end of the generation.
But this does not explain why it takes a man to generate a man. Note,
however, that a fully developed man is not only the end of generation;
it is also what initiates the entire process. For Aristotle, the
ultimate moving principle responsible for the generation of a man is a
fully developed living creature of the same kind; that is, a man who
is formally the same as the end of generation.
Thus the student of nature is often left with three types of causes:
the formal/final cause, the efficient cause, and the material cause.
However, the view that there are in nature causes besides material and
efficient causes was controversial in antiquity. According to
Aristotle, most of his predecessors recognized only the material and
the efficient cause. This explains why Aristotle cannot be content
with saying that formal and final causes often coincide, but he also
has to defend his thesis against an opponent who denies that final
causality is a genuine mode of causality.
Final Causes Defended
Physics II 8 contains Aristotle's most general defense of final
causality. Here Aristotle establishes that explaining nature requires
final causality by discussing a difficulty that may be advanced by an
opponent who denies that there are final causes in nature. Aristotle
shows that an opponent who claims that material and efficient causes
alone suffice to explain natural change fails to account for their
characteristic regularity. Before considering how the defense is
attempted, however, it is important to clarify that this defense does
not perform the function of a proof. By showing that an approach to
the study of nature that ignores final causality cannot account for a
crucial aspect of nature, Aristotle does not thereby prove that there
are final causes in nature. Strictly speaking, the only way to prove
that nature exhibits final causality is to establish it on independent
grounds. But this is not what Aristotle does in Physics II 8. Final
causality is here introduced as the best explanation for an aspect of
nature which otherwise would remain unexplained.
The difficulty that Aristotle discusses is introduced by considering
the way in which rain works. It rains because of material processes
which can be specified as follows: when the warm air that has been
drawn up is cooled off and becomes water, then this water comes down
as rain (Phys. 198 b 19-21). It may happen that the corn in the field
is nourished or the harvest is spoiled as a result of the rain, but it
does not rain for the sake of any good or bad result. The good or bad
result is just a coincidence (Phys. 198 b 21-23). So, why cannot all
natural change work in the same way? For example, why cannot it be
merely a coincidence that the front teeth grow sharp and suitable for
tearing the food and the molars grow broad and useful for grinding the
food (Phys. 198 b 23-27)? When the teeth grow in just this way, then
the animal survives. When they do not, then the animal dies. More
directly, and more explicitly, the way the teeth grow is not for the
sake of the animal, and its survival or its death is just a
coincidence (Phys. 198 b 29-32).
Aristotle's reply is that the opponent is expected to explain why the
teeth regularly grow in the way they do: sharp teeth in the front and
broad molars in the back of the mouth. Moreover, since this dental
arrangement is suitable for biting and chewing the food that the
animal takes in, the opponent is expected to explain the regular
connection between the needs of the animal and the formation of its
teeth. Either there is a real causal connection between the formation
of the teeth and the needs of the animal, or there is no real causal
connection and it just so happens that the way the teeth grow is good
for the animal. In this second case it is just a coincidence that the
teeth grow in a way that it is good for the animal. But this does not
explain the regularity of the connection. Where there is regularity
there is also a call for an explanation, and coincidence is no
explanation at all. In other words, to say that the teeth grow as they
do by material necessity and this is good for the animal by
coincidence is to leave unexplained the regular connection between the
growth of the teeth and the needs of the animal. Aristotle offers
final causality as his explanation for this regular connection: the
teeth grow in the way they do for biting and chewing food and this is
good for the animal.
One thing to be appreciated about Aristotle's reply is that the final
cause enters in the explanation of the formation of the parts of an
organism like an animal as something that is good either for the
existence or the flourishing of the animal. In the first case,
something is good for the animal because the animal cannot survive
without it; in the second case, something is good for the animal
because the animal is better off with it. This helps us to understand
why in introducing the concept of end (telos) that is relevant to the
study of natural processes Aristotle insists on its goodness: "not
everything that is last claims to be an end (telos), but only that
which is best" (Phys. 194 a 32-33).
Once his defense of the use of final causes is firmly in place,
Aristotle can make a step further by focusing on the role that matter
plays in his explanatory project. Let us return to the example chosen
by Aristotle, the regular growth of sharp teeth in the front and broad
molars in the back of the mouth. What explanatory role is left for the
material processes involved in the natural process? Aristotle does not
seem to be able to specify what material processes are involved in the
growth of the teeth, but he is willing to recognize that certain
material processes have to take place for the teeth to grow in the
particular way they do. In other words, there is more to the formation
of the teeth than these material processes, but this formation does
not occur unless the relevant material processes take place. For
Aristotle, these material processes are that which is necessary to the
realization of a specific goal; that which is necessary on the
condition (on the hypothesis) that the end is to be obtained. Physics
II 9 is entirely devoted to the introduction of the concept of
hypothetical necessity and its relevance for the explanatory ambition
of Aristotle's science of nature. In this chapter matter is
reconfigured as hypothetical necessity. By so doing Aristotle
acknowledges the explanatory relevance of the material processes,
while at the same time he emphasizes their dependency upon a specific
end.
The Explanatory Priority of Final Causes
In the Physics Aristotle builds on his general account of the four
causes in order to provide the student of nature with the explanatory
resources indispensable for a successful investigation of the natural
world. However, the Physics does not provide all the explanatory
resources for all natural investigations. Aristotle returns to the
topic of causality in the first book of the Parts of Animals. This is
a relatively independent and self-contained treatise entirely devoted
to developing the explanatory resources required for a successful
study of animals and animal life. Here Aristotle completes his theory
of causality by arguing for the explanatory priority of the final
cause over the efficient cause.
Significantly enough, there is no attempt to argue for the existence
of four fundamental modes of causality in the first book of the Parts
of Animals. Aristotle clearly expects his reader to be already
familiar with his general account of the four causes as well as his
defense of final causality. The problem that here concerns Aristotle
is presented in the following way: since both the final and the
efficient cause are involved in the explanation of natural generation,
we have to establish what is first and what is second (PA 639 b
12-13). Aristotle argues that there is no other way to explain natural
generation than by reference to what lies at the end of the process.
This has explanatory priority over the principle that is responsible
for initiating the process of generation. Aristotle relies on the
analogy between artistic production and natural generation, and the
teleological model that he has developed for the explanation of
artistic production. Consider, for example, house-building. There is
no other way to explain how a house is built, or is being built, than
by reference to the final result of the process, the house. More
directly, the bricks and the beams are put together in the particular
way they are for the sake of achieving a certain end: the production
of the house. This is true also in the case of natural generation. In
this context Aristotle' slogan is "generation is for the sake of
substance, not substance for the sake of generation" (PA 640 a 18-19).
This means that the proper way to explain the generation of an
organism like animal, or the formation of its parts, is by reference
to the product that lies at the end of the process; that is to say, a
substance of a certain type. From Aristotle we learn that Empedocles
explained the articulation of the human spine into vertebrae as the
result of the twisting and turning that takes place when the fetus is
in the womb of the mother. Aristotle finds this explanation
unacceptable (PA 640 a 19-26). To begin with, the fetus must have the
power to twist and turn in the way it does, and Empedocles does not
have an explanation for this fact. Secondly, and more importantly,
Empedocles overlooks the fact that it takes a man to generate a man.
That is to say, the originating principle of the generation is a fully
developed man which is formally the same as the final outcome of the
process of generation. It is only by looking at the fully developed
man that we can understand why our spine is articulated into vertebrae
and why the vertebrae are arranged in the particular way they are.
This amounts to find the role that the spine has in the life and
flourishing of a fully developed man. Moreover, it is only by looking
at the fully developed man that we can explain why the formation of
the vertebrae takes place in the particular way it does. (For further
information about the explanatory priority of the final over the
efficient cause, see Code 1997, pp. 127-143.)
Perhaps we are now in the position to understand how Aristotle can
argue that there are four (types of) causes and at the same time say
that proper knowledge is knowledge of the cause or knowledge of the
why (APost. 71 b 10-12, 94 a 20; Phys. 194 b 17-20; Metaph. 981 a
28-30). Admittedly, at least at first sight, this is a bit confusing.
Confusion dissolves when we realize that Aristotle recognizes the
explanatory primacy of the final/formal cause over the efficient and
material cause. Of course this does not mean that the other causes can
be eliminated. Quite the contrary: Aristotle is adamant that, for a
full range of cases, all four causes must be given in order to give an
explanation. More explicitly, for a full range of cases, an
explanation which fails to invoke all four causes is no explanation at
all. At the same time, however, the final/formal cause is the primary
cause and knowledge of this cause amounts to knowledge of the why.
There is, however, a caveat to be considered when interpreting this
claim. Aristotle is not committed to the view that everything has all
four causes, let alone that everything has a final/formal cause. In
the Metaphysics, for example, Aristotle says that an eclipse of the
moon does not have a final cause (Metaph.1044 b 12). What happens when
there is no final/formal cause like in the case of an eclipse of the
moon? An eclipse of the moon is deprivation of light by the
interposition of the earth which is coming in between the sun and the
moon. The interposition of the earth, that is, its coming in between
the sun and the moon, is to be regarded as the efficient cause of the
eclipse. Interestingly enough, Aristotle offers this efficient cause
as the cause of the eclipse and that which has to be given in reply to
the question "why?" (Metaph. 1044 b 13-15). The example of the eclipse
of the moon suggests that Aristotle's view is something like this: in
each and every case there is some cause that is the primary cause
about which one needs to know in order to have proper knowledge or
knowledge of the why, and where there is a final/formal cause, this is
the cause that one needs to know, but where there is not, the
efficient cause may fill its role. This may explain why Aristotle can
confidently say that "we claim we know each thing when we think we
know its primary cause" (Metaph. 983 a 25-26. Cf. Phys. 194 b 20).
Conclusion
Natural investigation was a search for answers to the question "why?"
before and independently of Aristotle. A critical examination of the
use of the language of causality by his predecessors together with a
careful study of natural phenomena led Aristotle to elaborate a theory
of causality. This theory is presented in its most general form in
Physics II 3 and in Metaphysics V 5. Here Aristotle argues that a
final, formal, efficient or material cause can be given in answer to a
why-question.
Aristotle further elaborates on causality in the rest of Physics II as
well as in Parts of Animals I. Here Aristotle explores the systematic
interrelations among the four modes of causality and argues for the
explanatory priority of the final cause. In so doing Aristotle not
only expands on his theory of causality; he also builds explanatory
principles that are specific to the study of nature. Aristotle
considers these principles an indispensable theoretical framework for
a successful investigation of the natural world. He expects the
student of nature to have mastered these principles before engaging in
the investigation of any aspect of the natural world.
Although Aristotle's theory of causality is developed in the context
of his science of nature, its application goes well beyond the
boundaries of natural science. This is already clear from the most
general presentation of the theory in Physics II 3 and in Metaphysics
V 5. Here the four causes are used to explain human action as well as
artistic production. In addition, any theoretical investigation that
there might be besides natural science will employ the doctrine of the
four causes. Consider, briefly, the case of Aristotle's Metaphysics.
Here Aristotle is seeking wisdom. Part of the argument of the
Metaphysics is in an attempt to clarify what sort of wisdom Aristotle
is seeking. Suffice it to say that Aristotle conceives of this wisdom
as a science of substance that is, or is a part of, a science of being
qua being (for further information about this argument, see the entry
Aristotle's Metaphysics, especially Sections 1 and 3.) What is
important is that this science consists in a causal investigation,
that is, a search for the relevant causes. This helps us to understand
why the most general presentation of Aristotle's theory of causality
is repeated, in almost the same words, in Physics II 3 and in
Metaphysics V 5. Although the Physics and the Metaphysics belong to
two different theoretical enterprises, in both cases we are expected
to embark on an investigation that will eventuate in causal knowledge,
and this is not possible without a firm grasp of the interrelations
between the four (types of) causes.
http://plato.stanford.edu/entries/aristotle-causality/
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