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Dictionary of the History of Ideas

Studies of Selected Pivotal Ideas
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The views of causation among the literate peoples of
the ancient world exhibited the almost universal tend-
ency of antiquity as well as of modern pre-literate
cultures, to interpret natural phenomena in terms ap-
plicable only to the arrangement of human society, or
at least to the actions of intelligent agents. Such, at
any rate, seems to be the judgment of the best students
of ancient Mesopotamian and Egyptian civilizations.
These views have been called “mytho-poeic” and
“socio-morphic” accounts of the natural world because
they are myths in categories devised either to explain
who brought about the present state of the cosmos or
to explain the regular or periodic routine of nature.
For example, the alternation of seasons and the position
and movement of the heavenly bodies were thought
to be the result of decrees and arrangements made by
the gods. These divine decrees or arrangements were
conceived in close analogy to the regular arrangement
of society or the edict of a law giver. The clear and
sharp distinction between personal and impersonal or
the difference between nature and society, so familiar
to modern man, did not seem to exist for the ancient
world at that time. In particular, the systems of retribu-
tive justice were applied to explain the phenomena
of nature. The details of this view of the universe and
its regularity have been discussed in a number of treat-
ments of ancient Mesopotamian and Egyptian civili-
zations (Frankfort, Wilson, and Jacobsen, 1949).


Early Greek philosophy reveals the survival of such
notions especially in fragments of Anaximander, Par-
menides, and Heraclitus. That some kind of retributive
justice holds things to the right order is indicated in
a number of places, e.g., Anaximander's statement that
“things pay penalty and retribution to one another for
their mutual injustice according to the decree of time”
provides one such survival (Diels, Fragmente, 12A).
Heraclitus' statement that the handmaids of justice
watch over the sun in his courses (ibid., 94B), and
Parmenides' doctrine that justice holds fast what exists
in fetters, provide others.

Although there are other such vestiges of pre-philo-
sophic ideas among earliest Greek philosophers, Greek
philosophy's formal beginnings succeeded in making
considerable advances beyond this style of thought.
There is some evidence that the Milesian and other
early schools conceived the ultimate source of all things
as being something divine. There was a tendency to
de-personalize this divine being, and with this came
an absence of caprice, that is, the regularity of natural
phenomena was made to depend on a regularity in the
operation of their cause or causes. Moreover, the anal-
ogies drawn from observation tend to be drawn from
natural and observable connections. Anaximenes, for
example, explains the different states of matter in terms
of rarefaction and condensation. This explanation is
radically different from anything like a mytho-poeic
or socio-morphic category. Of course, mythic explana-
tions continue to be found, but even they take on a
different character.

The problem of causality explicitly appears at the
beginning of the fifth century B.C. The first philosophers
of Greek antiquity were concerned with genuine sci-
entific and philosophic problems: What is the substance
from which all things arise and to which they return?
What is the nature of change? It was soon discovered
that it is impossible to believe that the universe consists
of a single simple substance and that change can also
occur. The difficulty received its classic formulation
from Parmenides. Being or that which is, cannot arise
from nonbeing; and what is, cannot cease to exist.
From this came the celebrated maxim that ex nihilo
nihil fit.
At first, this maxim, that nothing can come
from nothing, was applied to justify a material sub-
stratum, but when the pluralistic systems of Anaxagoras
and Empedocles were developed, the maxim was ap-
plied not merely to the eternity of the elements, but
also to the eternal elemental forces which served to
combine and separate the eternal elements. In this way,
causal principles were introduced: events require both
underlying permanent substances and forces to explain
the various combinations and arrangements of things.
The primary beliefs in a causal and substantival order
were elaborated into fundamental principles of philos-
ophy. The first explicit statement was made by Melissus
of Samos (fl. 440 B.C.), “That which was, was always
and always will be, for if it had come into being, it
necessarily follows that before it came into being,
nothing existed, but if nothing existed, in no way could
anything come into being out of nothing” (Diels, 1B).
The verbal character of Melissus' originality will not
escape the modern reader. To say that X comes from
nothing is to say of “nothing” what can be significantly
asserted of something. It is true that an empirical proof
of this maxim was attempted much later by Epicurus
and his followers, but the earlier attempts to argue the
point are entirely nonempirical in character. But how-
ever it was established in ancient Greek philosophy,
the principle was accepted almost without challeng
until the eighteenth century.

The belief in the pervasive character of the causal
nexus can be found also among the medical writers
of the fifth century. In the Hippocratic medical writ-
ing, The Art (Loeb, Vol. II), we read that everything
which occurs does so through something, so that
“spontaneity” is a mere name and has no reality.

The first full expression of principles of causation
can be found in the writings of Plato and Aristotle.
Plato expresses his views on the necessity of causation
in several places. In the Timaeus 28A; also in the Laws
895, in the Philebus 26, and in the Parmenides 138,
he asserts that “whatever becomes must necessarily
become, owing to some cause; without a cause it is
impossible for anything to achieve becoming.” Since
the Forms are eternal and unchangeable, they require
no causal explanation. (There is only one passage which
is inconsistent with this. It occurs in the Republic 597.)
But the realm of physical objects including organisms,
is derivative in two different ways and therefore re-
quires a cause of change. Physical objects and orga-
nisms are copies of Forms and are always changing
and being thus insufficient, require causes of their
generation. However, it is impossible to discover what
Plato means by the necessity of a cause. Plato also
retains a counterpart of the material from which things
are composed, the so-called Receptacle. We can thus
discern some of the prototypes of Aristotle's four causes
in these views.

One feature of Plato's thought about causation de-
serves a special mention. This is the element of tele-
ology—the idea that natural changes were intelli-
gently directed by an intelligent and divine agent had
never been completely eliminated from early Greek
speculation. The attempt of the Sophists radically to
distinguish between nature and society, had it been
successful, might have led the way to a completely
mechanical account of natural processes. Indeed, sug-


gestions of such an account are perhaps indicated by
the views of the Greek Atomists. The one remaining
statement of Leucippus and what we can reconstruct
from the views of Democritus as well as the revival
of Atomism by the Epicureans, show that the Greeks
were capable of conceiving of natural processes in
purely mechanical terms. But the philosophy of Plato
and Aristotle so completely overshadowed this attempt
that it is fair to say that the teleological explanation
dominated European thought until the seventeenth
century. Plato's teleology, to be sure, was considerably
different from that of Aristotle. According to Plato,
the order and arrangement of the world resulted from
the action of a divine Artificer who, looking to the
Forms as a model of perfection, fashioned the world
out of some kind of pre-existing eternal but recalcitrant

The most elaborate treatise of causality in Ancient
Greek thought, is to be found in Aristotle. In the first
place, he distinguished four senses of “cause”: the
material out of which things come; the form which
things eventually have when they are perfected; that
which brings about this completion, the moving cause;
and finally the purpose or function of such things, the
final cause. Thus there is a teleological interpretation
of causal transactions but it is a teleology of a very
special sort. For these ends or purposes, which are
realized by natural objects when they achieve their
perfection, are not imposed from without but rather
arise from their intrinsic natures. All things naturally
tend toward intrinsically determined goals. The ulti-
mate cause of this tendency or natural striving is God,
who moves things by being the object of their desire.
This tendency has gone on from eternity and will go
on without end.

Some important details of Aristotle's views on causa-
tion must now be discussed. Like Plato, Aristotle
maintains that the cause of change must be assumed
as an absolute necessity. Everything which undergoes
change is made to do so necessarily by something
(Physics 7, 241b, 25). This necessity of a cause of
change is explained in the following way: motion is
the process of actualization of what is capable of being
so moved. What undergoes change is what has a po-
tency or capacity to do so (Physics 251a, 12). Now this
actualization of potency by definition requires an ac-
tual agent (Physics 257b, 9). Nothing which has a
capacity to undergo change can bring about that
change by itself (Metaphysics 107b, 29-31). All these
statements, as is obvious, really depend on the defini-
tion of change as the actuality of potency, so that the
necessity that change be effected by something distinct
from what undergoes change, depends on the definition
which Aristotle gives. It is true that Aristotle provides
considerations which he thinks ought to induce us to
accept such a characterization of change, but the re-
peated insistence that these principles are necessary
plainly depends on his definition. From this definition
of change a number of special causal principles are
derived. First, it is clear that similar changes require
similar causes and conversely, similar causes will al-
ways give rise, if there is no interference, to similar
changes. (There is an exception to the second of these
principles in the case of free agents so that the princi-
ple must be qualified so as to apply only to what
Aristotle calls irrational potencies, 1046b, 5-6; 1048a,
8 et passim.) Furthermore, the cause and the effect
must be alike either ostensibly or covertly (1049b). It
is for this reason that Aristotle denies what Mill later
called the “plurality of causes.” Since each of two
effects of the same kind must resemble its cause, the
causes will be identical in species or in genus. This
is the rationale behind Aristotle's discussion of the point
in Posterior Analytics, Book Two, Chs. 16-18.

To summarize, every change requires a cause that
resembles the change in question and such causal
transactions (with the exception noted above) occur
with regularity if there is no interference. The dis-
covery of particular causal routines depends ultimately
on the direct observance of repetitions in the natural
world. By induction from the observance of particular
cases, we infer universal propositions which formulate
these routines. Aristotle nowhere explicitly provides
the ground for such inductive inferences from particu-
lars to the general case, but his medieval successors
suggest the following argument: what happens always
or for the most part, cannot be due to chance; there-
fore, if we see in a number of cases that under condition
A, an object of the kind C is attended by changes of
the kind E, we can take this as a clear indication of
the universality of the principle.

Another important feature of Aristotle's views on
causation requires mention. Causal connection is si-
multaneous determination (Metaphysics, Book 5, Ch.
2, 1014a, lines 20f.). It is not easy to see how this
doctrine, that cause and effect are mutually simulta-
neous, can be made consistent with any temporal suc-
cession of events in the world.

The Stoics and Epicureans are as insistent as their
predecessors about the necessity of a cause for every
change. According to the Stoics “Nothing takes place
without a preceding cause” (Plutarch, 11, 574) “... this
determining cause acts by necessity and any apparent
chance or apparently causeless event is due to a hidden
cause” (ibid., 7, 572). The Stoics are well known for
their deterministic view of the universe which they
find not a little difficult to reconcile with the apparent
facts of human choice. A peculiarity of the Epicurean


view of the causal principle deserves mention. Epicurus
maintains that nothing comes into existence from what
is nonexistent. Otherwise, he holds, anything would
have come from anything since it would have no need
of a proper and appropriate origin or seed (Diogenes
Laërtius, X, 39). His argument is stated in detail by
Lucretius (De rerum natura, I, 160). The argument
seems to be something like the following: if the princi-
ple ex nihilo were false, then anything would have
come from anything and if anything would have come
from anything, then the resemblance between parent
and offspring in the case of both plants and animals
would be exceedingly rare or absent. But on the con-
trary, the resemblance in question is an absolute rule
so far as observation informs us; therefore, the principle
“from nothing, nothing comes” is justified. Whatever
may be thought of the weakness of this argument, it
is at any rate an empirical argument for a principle
which in earlier thought had been largely urged for
nonempirical reasons and, in this respect, is almost

The Greek skeptics raised serious doubts about the
principles of causation which we have already encoun-
tered. But it is worth noting that none of their argu-
ments is anything like the critical considerations
about the nature of causal connections which are asso-
ciated with the name of Hume. It is true that some
of the views about our knowledge of substance can
be traced to the skeptic Carneades and it is also true
that the contention that we have only probable cogni-
tion about things and processes in the world came from
the same source. But the skeptical arguments which
Hume used to such great effect, cannot be found in
any of the discussions of the skeptics of antiquity.

We come now to Neo-Platonism. The principal con-
tribution which the Neo-Platonists made to the concept
of causal connection is this: that effects not only re-
semble their causes and causes resemble their effects,
but also that the effect has some kind of pre-existence
in its cause and conversely, that the cause has some
kind of post-existence in its effect. The Neo-Platonic
doctrine that all things emanate from a single ineffable
source, that these things therefore pre-exist in and
emerge from this source lies at the foundation of their
view of the causal nexus. This view is associated with
many of the medieval discussions of the subject. Even
those philosophers and theologians who do not accept
the main contention of the Neo-Platonists, viz., that
all reality emanates from an inexhaustible fountain of
existence, nevertheless do accept some form of the
principle that the effect has some kind of pre-existence
in the cause.

The intellectual tradition of antiquity was largely
assimilated by medieval Jewish, Christian, and Muslim
philosophers. Augustine, for example, assumes without
argument that every event must have a cause and
argues for it in a somewhat simplistic way. In Chapter
17 of Book 2, On the Free Will, he holds that nothing
can give itself form because nothing can give itself
what it does not have. So that if it does not have form
at the outset and cannot receive from itself what it
does not possess, it must receive this from something
other than itself. The pre-existence of all things in the
ultimate cause, God, is conceived in semi-Platonic
terms: the Archetypes or Exemplars of all finite beings
exist in the mind of God. Many statements of the
necessity of causation can be found in Augustine's
writings (De ordine, De Trinitate, De genesi contra
) and his views are echoed by a number of
medieval Christian theologians of the early medieval
period. For example, Anselm in The Monologium,
Chapter 3, holds that it is altogether inconceivable that
anything could exist without a cause.

The Muslim philosophers developed a conception
of causality largely dependent on Aristotle and usually
modified by Neo-Platonic doctrines. This was largely
due to the fact that some pseudo-Aristotelian writings
circulated among them and partially due to the further
circumstance that some of them, for example Al-
Farabi, found the philosophy of Plato and Aristotle to
be mutually harmonious. Al-Kindi, Al-Farabi, Ibn-Sina
(Avicenna), and Ibn-Tofail all accept as self-evident the
principle that whatever exists after not having existed
needs some producing cause. The tenth-century system
of Avicenna is especially important both as a complete
representation of philosophy in the Near Eastern world
of the eleventh century and because of its influence
on Christian thought in the early thirteenth century.
He adopted an elaborate form of the Neo-Platonic
emanation-theory in terms of which the genesis of the
universe from the Godhead was conceived as necessi-
tated. The first Being is absolutely necessary (in fact
it is called the “necessary being of existence,” ens
). All other realities emanating therefrom
are possible beings considered in themselves, but nec-
essary beings considered in terms of their cause. The
universe in this concept is an organic system in which
causal interrelations of all things are strictly observed.
In the System of Al-Kindi, the causal influence of
everything upon everything else is emphasized follow-
ing earlier Neo-Platonic suggestions so that a kind of
universal harmony is achieved. This is carried to such
an extent that Al-Kindi maintains that a complete
knowledge of any single thing would reveal the nature
of the entire universe.

The first medieval critique of the maxims of causality
comes from the school of orthodox theologians founded
by Al-Ashari. This school defended the doctrine that


God is the only cause and that the ordinary regularities
in the natural world are only the result of God's usual
mode of action. The most detailed defense of this
medieval Occasionalism is to be found in the writing
of Al-Ghazali (1058-1111), The Incoherence of Philoso-
In this attack on the philosophical system of
Avicenna, Al-Ghazali argued that there was neither
empirical nor logical warrant for ascertaining the
existence of causal connections among any finite things.
He asks why philosophers hold that fire is the cause
of combustion, say of a piece of cloth. The philosopher
can give no reason for this except the observance that
combustion occurs on contact of a flame with the cloth.
But this shows only that the combustion occurs to-
gether with the contact but not as a result of it. In
other words, the empirical observation of the con-
comitance of two events reveals no causal interaction.
Moreover, the connection between the so-called cause
and its alleged effect is not necessary. There is only
one kind of necessity, viz., logical necessity and no
logical necessity can exist between two distinct things
or events. For if one of these is distinct from the other,
the affirmation of one does not include that of the other
nor does the negation of one include the negation of
the other. The only reason that there appears to be
any logical connection between distinct events or ob-
jects is because the description of one of the two in-
cludes reference to the other. But this is purely verbal,
and in no wise proves a real connection of the events.

The reader will immediately recognize the resem-
blance between Al-Ghazali's criticisms of causality and
that of Malebranche and Hume. (No evidence exists
to establish an historical connection here.) Al-Ghazali's
critique of causality as well as his attack on other
aspects of philosophy practically terminated any origi-
nal philosophical speculation in the Muslim world of
the Near East. His work was elaborately examined
much later by Ibn-Ruschd. Ibn-Ruschd (Averroës) was
perhaps closest to Aristotle of all the Muslims. In his
attack on Al-Ghazali, The Incoherence of the Incoher-
and in other writings, he correctly points out that
a denial of the principle of causality between finite
events, cuts the ground entirely from any attempt to
prove the existence of a god, for without any empirical
evidence of causal connection among finite beings,
there is no way left for us to infer the existence of
the unobserved from that of something observed. In
this, Ibn-Ruschd was perfectly correct, but he does not
really succeed in answering Al-Ghazali's criticisms.

The only distinctive contribution to the subject of
causality among the medieval Jews was made by Ibn-
Gabirol (Avicebron). According to his doctrine, the
only truly efficacious force in the universe is the will
of God which holds matter and form together through
out the universe. As we proceed from God down
through the hierarchy of things, this force is debilitated
so that in the world of corporeal objects, we find beings
incapable of exerting any efficacy whatever. The other
philosophers among the Jews maintain views on cau-
sality which are sufficiently similar to those already
mentioned and merit no special attention.

The translations of the major works of Aristotle into
Latin during the twelfth and the thirteenth centuries,
as well as translations from Jewish and Arabic philoso-
phy made at the same time, provided a new impetus
to philosophical speculation in Christendom. In one
of the earlier discussions of the subject by Robert
Grosseteste, On Potency and Act, we find the charac-
teristic Aristotelian doctrine that everything which is
caused is caused by something similar to itself either
in species or according to some analogy. From this,
it follows that the act of any potency precedes it and
this act is like the potency it actualizes either specifi-
cally or analogically.

The most detailed discussion of causality is to be
found scattered through the writings of Aquinas.
Aquinas' discussions are enriched by the development
of logic from the twelfth century onward, and by the
fuller understanding of Aristotle's views. Aquinas
maintains all of the familiar Aristotelian doctrines.
Everything which is brought into actuality from po-
tency requires a cause which is like the potentiality
it actualizes, and all changes require causes, and this
requirement is one of absolute necessity. Finally that
this necessity is logically conceived is put beyond all
question by Aquinas' argument in the Summa theolog-
(Part I, Qu. 44, Art. 1). Here Saint Thomas is
arguing that everything excepting God Himself, must
be created. Now some people have maintained that
since any given kind of being does not involve the
notion of being caused as a part of its definition, there
is no reason why any member of such a kind may not
exist without being created. To this, Thomas replies
that, although a connection with a cause is not a part
of the definition of the kind of thing which is caused,
this connection still follows from some aspect of its
nature. For from the fact that something exists by
participation in Being, it does follow that it must be
caused by something other than itself. A similar con-
sideration taken from Thomas' proof for the existence
of God (ibid., Part I, Qu. 2, Art. 3) shows that the
relation between things and their causes is logically
necessitated. There Thomas argues to the necessity of
a cause of every change from the Aristotelian definition
of change. Since change is the actualization of a po-
tency, anything which undergoes change must be ac-
tualized by something, and since nothing can actualize
itself, the change must be effected by something other


than the object undergoing it. Thomas insists that all
finite beings have their own appropriate capacities
both to undergo and to induce change. This doctrine
is held to be consistent with the view that God cooper-
ates with His creatures whenever any of them exercises
its own proper causal efficacy.

A crisis in medieval Christian philosophy occurred
in the last quarter of the thirteenth century. The ex-
positors of Aristotle in the Faculty of Arts at the Uni-
versity of Paris insisted on their obligation to expound
Aristotle's natural philosophy even on points where it
conflicted with the tenets of Christian dogma. Accord-
ingly, they held that in natural philosophy, creation
from nothing is impossible. Every new being must be
generated from a pre-existing matter. Also there is no
exception to the regular and characteristic activities
of natural objects, so that there is no room in the
natural world, as conceived by Aristotle, for any mira-
cles. Again, the causal dependence of accidents on their
substrata admits of no exception. Now all this was in
patent conflict with Christian dogma. The doctrine of
creation from nothing, the miraculous suspension of
the causal powers of natural objects, and the existence
of accidents without a material substratum in the
Eucharist to all of which Christians were committed
could not be reconciled with Aristotelian natural phi-
losophy. Accordingly, serious adjustments were re-
quired. Of course, this had been realized by the scho-
lastics before the great condemnation of strict
Aristotelism in 1277, but the matter did not assume
critical proportions until that time.

These adjustments took several forms. In Duns
Scotus, the essentially Aristotelian view about causal
connection is generally maintained with one important
qualification. Instead of holding that finite creatures
will exercise causal efficacy whenever circumstances
are appropriate, Duns Scotus maintained that these
beings are so constituted that they will exercise their
powers if and only if God cooperates. So we cannot
say that causal connection is inevitable, but only that
finite things are naturally apt to act in their charac-
teristic ways.

A somewhat more radical view can be found in
Ockham and his successors. While it is very clear that
Ockham believed in the efficacy of natural causes, his
epistemological reservations concerning our knowledge
of causal connection paved the way for the radical
skepticism which is characteristic of some of the four-
teenth-century theologians. According to Ockham, the
only way in which we can establish any causal connec-
tion between one thing and another is the observation
that when one of these occurs, the other also occurs
at the same time and at or near the same place. Since
it is logically possible that God may at any time per
form a miracle, it is impossible to provide absolute
evidence for any causal transaction (Sentence II, 8-5).
Sufficient evidence however, for causal transactions,
can be found in the aforementioned criterion of spatio-
temporal concomitance. What is important however,
is that Ockham insists that this is the only way to
establish causal connection. Once we have established
such a connection in a single instance, we can infer
the proposition that this connection holds for all cases
of the kind, by the self-evident proposition that all
things of the same kind produce effects of the same
kind in appropriately disposed objects under the same

A more radical view of the subject was expounded
by Nicholas of Autrecourt. He has been called a medi-
eval Hume, and his right to this title is based on some
letters to a certain Bernard of Arezzo. In these letters,
he maintained that all certitude is based on and re-
ducible to the immediate evidence of experience and
the Principle of Contradiction. But there is no absolute
evidence derived from experience that any natural
causes operate. Moreover, it is a consequence of the
Principle of Contradiction that in every valid inference
the consequent simply restates all or part of what was
stated in the antecedent. Hence from the fact that one
thing is known to exist, it cannot be inferred with the
evidence of the Principle of Contradiction that another
and different thing exists. From this, it follows that
effects cannot be logically inferred from alleged causes
nor conversely. Thus, though there may be a probability
for causal connection, there can be no certainty that
any natural causes exist. Neither experience nor logical
reasoning can provide such certainty. Nicholas' views
were hotly contested by his contemporary, John
Buridan, but his criticisms of Nicholas fall short of the
mark. The influence of Nicholas of Autrecourt extends
into the next century, for we find his arguments used
by Cardinal Pierre d'Ailly and others. Many other
authors in the fourteenth century exhibit similar critical
tendencies concerning the great metaphysical questions
of causality, substance, and the like, but the majority
of scholastic writers continue to maintain views similar
to those of the great thirteenth-century scholastics.

The philosophy of the Renaissance represents re-
vivals of antiquity's theories or the continuation of
medieval doctrines on the subject. Neo-Platonic, Stoic,
and Epicurean doctrines all find their champions at
this time. Even ancient Greek skepticism found its
early modern representative in the fifteenth and six-
teenth century, but nothing distinctively new emerged
until the period of the great discoveries in physical
science of the seventeenth century.

One of the main modifications of medieval views
about causal connection depends on the new concep-


tion of intertia introduced by Galileo and Descartes.
In accordance with this notion, it is no longer necessary
to assume a cause in order to explain continuation of
motion or rest. Nevertheless, philosophers and scientists
continue to maintain the necessity of a cause for every
new event. In some cases, novelty involves either a
change in velocity or direction. Nonetheless, causes are
always presupposed. In Descartes, we find the assertion
that everything which exists requires a cause (Reply
to the Second Objections: Axiom I). Moreover, the
principle that causes must be adequate to their effect
is applied by Descartes in a new way; even the content
of our ideas requires adequate causes and it is this
principle which Descartes employs in his main proof
for the existence of God. Descartes' radical daulism
between mind and matter introduced a special prob-
lem: How can there be any causal interaction between
things so very different as mind and extension? The
causal interactions within the physical realm are ex-
plained exclusively in terms of the communication of
motion. But since motion is conserved, there is a diffi-
culty in explaining how human volition can in any way
modify the actions of bodies. Either Descartes or his
immediate successors supposed that human volition
could modify the direction of a motion without chang-
ing the total amount of motion in the universe. But
many of the successors of Descartes were unsatisfied
with this explanation and introduced the doctrine of
Occasionalism. The best known of the Occasionalists
was Malebranche. In his De la recherche de la vérité
(The Search for Truth, 1674), he defined a real cause
as something between which and its effects, the mind
perceives a necessary connection. Now since only the
Infinite Being is one between whose will and its effects
the mind perceives necessary connection, God is the
only real cause. He supports this view in two ways:
(1) we see no necessary connection between any finite
being and its alleged effects; and (2) observation reveals
only succession and no genuine causation. Conse-
quently, all events are caused by but one being, namely
God. Other Occasionalists such as Cordemoy and
LaForge, used other arguments to support the same

In Britain, Hobbes maintained a strictly materialistic
account of all causal interaction, and Francis Bacon
attempted to formulate the methods by which causal
connections could be discovered. Even there, some
skepticism about the discernment of causal connection
is expressed by a number of authors. Newton's teacher,
Isaac Barrow, in his Mathematical Lectures (ed. W.
Whewell, 1800) held that only in mathematics can any
necessary connection be established so that no connec-
tion of an external efficient cause with its effect can
be established by logical considerations. Joseph Glan-
vill in The Vanity of Dogmatizing (1661) expressed
similar doubts.

Locke, both in his Essay Concerning Human Under-
and in his controversy with Stillingfleet,
maintained that the proposition, “Whatever has a be-
ginning has a cause,” is a principle of reason which
can be justified simply by the analysis of the meaning
of the terms “beginning” and “being caused.” The idea
of power is derived, according to Locke, from our
expectation of the constant concomitance of two
events, but he nowhere explains satisfactorily how this
concomitance reveals anything more than regularity
in the occurrence of events. It is true that he finds
direct evidence of activity in the action of the mind
which is immediately observed, but how this direct
observation of mental activity is connected with any
physical changes, he leaves entirely unexplained.

Berkeley's philosophy introduced an idealism which
tried to refute the materialistic interpretation of the
world external to (“without the”) mind. The only place
where activity is directly encountered is in the activity
of our own spirit. The ideas which are the content of
mind are causally inefficacious. Yet Berkeley assumes
without question and without discussion, that there
must be some cause (ultimately God) of those ideas
which are not the result of human volition. So on the
one hand, the regularity of our experience does not
imply the relation of cause and effect; but on the other
hand, the existence in us of ideas which we did not
ourselves produce, indicates some other cause which
Berkeley construes as divine activity.

On the Continent, the two great systems of the
seventeenth century were those of Spinoza and Leib-
niz. Spinoza conceives causal interaction essentially in
two different ways: on the one hand, every event in
the universe is a necessary consequence of the divine
nature so that cause and logical ground are identified;
on the other hand, the finite chains of events which
constitute the regularities of nature, through somehow
dependent upon the necessary causality of God, are
not satisfactorily integrated into his system. The prob-
lem of the causal interaction of mind and matter is
resolved by Spinoza in terms of an identity theory.
Mental and physical occurrences are two aspects of
the same event so that the Cartesian problem of inter-
action is resolved. Leibniz denied any causal or spatio-
temporal relations among the monads or centers of
energy (vis viva) which constitute his universe. Instead
of causal connection, he postulated a “pre-established
harmony” among the monads in terms of which the
states of any given substance correspond to the states
of all the other substances in the universe. This corre-


spondence was established by the deity at the begin-
ning of creation because God selected just those sub-
stances whose successions of states would exhibit this
harmony. There is, however, a real causality within
each monad, for in each monad, the later states emerge
from the earlier according to the law of succession
which determines the life history of each monad (as
a mathematical function determines the relations of
the elements of an algebraic series). Moreover, all the
monads are causally dependent on the deity at each
moment of their several existences.

The most important contribution to the subject of
causal connection in modern philosophy was made by
David Hume. Although Hume's arguments were antic-
ipated by the medieval Muslim Ash'arites, Al-Ghazali,
and by Nicholas of Autrecourt and others in the Middle
Ages, and to some extent by the French Occasionalists
of the seventeenth century, Hume's way of putting
these arguments as well as his explanation of necessary
connection, was a distinctly novel contribution. Ac-
cording to Hume, logic is incapable of providing a
foundation in reason for the several received maxims
concerning causal connection. That every beginning
must have a cause, that like antecedents will always
be followed by like sequents, and that a cause must
be like its effect had, in the great majority of Hume's
predecessors, been regarded as principles for which
reason could provide an absolute justification. Hume
rejects all this by a series of brilliant criticisms of all
the traditional attempts in this direction, and he con-
cluded that the belief in causal connection has an
entirely different foundation. We observe nothing but
the regular succession of events. This repetition in our
experience produces a felt expectation which Hume
calls “an impression of reflection.” This impression is
projected onto the objects revealed by sensation and
so we mistake a feeling in us (“felt expectation”) for
a connection of objects with one another. The idea of
necessary connection is thus derived from habitually
felt expectation and has no other foundation. A cause
is nothing but an object precedent to and contiguous
with some other object and such that objects like the
former stand in a similar relation of precedence and
contiguity to objects like the latter. Causation con-
sidered as a natural relation has the further aforemen-
tioned feature of habitually felt expectation which is
contributed by the mind of the observer and is in no
way a constituent of the objective situation. The uni-
formity of nature according to Hume, does in fact exist,
but our belief in it is a matter simply of customary
expectation and it can have no foundation in reason;
nor does the so-called principle of the “uniformity of
nature” have even any probability since all probable
arguments presuppose this principle and thus can never
be used as its justification.

Hume's psychological explanation of causal belief
seemed to constitute a threat to the foundations of
natural science. 'Immanuel Kant, while accepting
Hume's negative critique of previous a priori views of
necessary connection in causality, nevertheless re-
garded Hume's theories of the genesis and nature of
causal belief inadequate. Since Kant believed that nat-
ural science was firmly established—especially with
Newton's universal laws of physical phenomena—he
felt obliged to give another account of causal connec-
tion as well as of all our experience of physical objects,
and he thought that he discovered this new account
in the original constitution of human cognition. Ac-
cording to Kant, our minds so operate as to construe
the congeries of sensation in substantival and causal
ways. The necessity for causal connection is thus de-
pendent on the structure and function of the human
mind. The principle of causality is valid for all human
experience because the human mind construes experi-
ence ineluctably in causal ways. It was by this means
that Kant supposed that he could rescue natural science
from the skepticism of Hume. The principle of causality
has absolute and objective validity as applied to the
entire range of experience. Kant's principal argument
is to be found in “The Second Analogy of Experience,”
in his Critique of Pure Reason. There he argued that
the objectivity of succession can be explained only in
terms of the way all human minds construe the succes-
sion of events revealed in sensation.

Several quite different developments constitute the
subsequent history of reflections about the nature of
causal connection. The absolute idealists, particularly
Hegel, account for the connections of things with one
another by a radical modification of logic which they
substitute for the logic of contradictories—the logic
in which the questions of causality had been discussed
in almost all earlier philosophy. Hegel introduced the
dialectic of contraries. This innovation made it possible
to connect distinct things by virtue of their very dis-
tinctness. Earlier philosophers had raised the question
“How can different things be causally related?” But
Hegel's dialectic converted this question into another
one, viz., How can distinct things fail to be connected?
In other words, the very difference of distinct aspects
of reality required their interconnection and ultimately
their interdependence. All reality so construed becomes
one systemic whole in which all the parts are inter-
dependent. This doctrine achieved the result which was
desired but at the great cost of replacing standard logic
with what Hegel called dialectical logic but what was
in reality an entirely new metaphysic.


The principal contribution to the subject from the
nonidealist side was made by Maine de Biran, who
argued that we have a direct experience of causal
efficacy in the actions of our own consciousness. A later
and somewhat different form of this view was cham-
pioned by A. N. Whitehead. He distinguished between
two radically different kinds of perception—perception
in the mode of presentational immediacy and percep-
tion in the mode of causal efficacy—and maintained
that the latter revealed to us direct and unmistakable
evidence of causal interaction. The main difficulty with
contentions of this kind had already been anticipated
by Hume. Even if there is some unique feature of
experience which we are inclined to regard as a direct
evidence of efficacy, it would serve in no way to guar-
antee the existence of repeatable causal routines in
nature. Yet, it is the repeatability of succession that
is an essential ingredient in any useful notion of causal
connection and this, the alleged perception in the mode
of causal efficacy does not and cannot guarantee.

The development of natural science since the seven-
teenth century has tended to emphasize functional
determination, for example, as expressed in the gener-
alizations of physics and chemistry, rather than regu-
larities of succession, and the equations of physics
provide little or no basis for the layman's belief in
causal connection as conceived by earlier philosophical
discussions of the matter. While it is still true that in
the less advanced sciences, laws of succession continue
to play some role, the possibility of the ultimate expla-
nation of these laws by derivation from the generaliza-
tions of the more exact sciences, renders any ultimate
concern with these laws of succession relatively un-

Some final consideration must be given to the dis-
coveries in the realm of physics concerning Heisen-
berg's Principle of Indeterminacy. Whatever ultimate
interpretation may be given to this principle, it appears
at present that strict and unexceptional regularity
in the occurrence of events in the subatomic realm
must be given up and statistical rather than nomic gen-
eralizations—laws asserting necessary connection—
accepted as the best characterization of the relation
of events at this level.

The conviction that some kind of uniformity governs
the play of events in the natural world has been one
of the most influential beliefs of man since the begin-
ning of human reflection. Attempts of various kinds,
as we have seen, were made to base this conviction
on the deliverances of reason. In particular, the belief
that the causal maxims could be established by purely
logical considerations, dominated almost the entire
history of the subject. The criticisms of this rationalistic
view of causal connection gradually undermined these
convictions so that today it is not too much to say that
they have been abandoned by a considerable number
of philosophers and are in no way operative in the
practice of scientists.


There are standard editions of major authors and the
following selected works are also helpful.

Primitive Period. Henri Frankfort, Mrs. Henri Frankfort,
John A. Wilson, and Thorkild Jacobsen, Before Philosophy
(Harmondsworth, 1949). Hans Kelsen, Society and Nature
(Chicago, 1943). R. B. Onians, The Origins of European
(Cambridge, 1951).

The Greeks and Romans. Cyril Bailey, The Greek Atomists
and Epicurus
(Oxford, 1928). F. M. Cornford, Plato's Cos-
(London, 1937). Diels-Kranz, Die Fragmente der
5th ed. (Berlin, 1951-54). S. Sambursky, Phys-
ics of the Stoics
(London, 1959). F. Solmsen, Aristotle's
System of the Physical World
(Ithaca, 1960). Léon Robin,
Pyrrhon et le scepticisme grec (Paris, 1944).

The Medieval Period. Léon Baudry, Lexique philo-
sophique de Guillaume d'Ockham
(Paris, 1958), article
“Causa.” M. Fakhry, Islamic Occasionalism (London, 1958).
Erich Hochstetter, Studien zur Metaphysik und Erkenntnis-
lehre Wilhelms von Ockham
(Berlin, 1927). Michalski Kon-
stanty, “Le criticisme et le scepticisme dans la philosophie
du XIVe siècle,” Bulletin International de l'Académie Polo-
naise des Sciences
(1919-25). Francis Meehan, Efficient
Causality in Aristotle and St. Thomas
(Washington, D.C.,
1940). J. Obermann, “Das Problem der Kausalität bei den
Arabern,” Festschrift Joseph R. von Karabacek (Vienna,
1916), pp. 15-42.

The Modern Period. Maine de Biran, “Essay upon the
Foundations of Psychology,” The Classical Psychologists, ed.
Benjamin Rand (Cambridge, 1912). Standard editions of René
Descartes, Meditations and Principles of Philosophy; Thomas
Hobbes, Works; David Hume, Treatise of Human Nature
and Enquiry Concerning Human Understanding; Immanuel
Kant, Critique of Pure Reason. G. W. Leibniz, Leibniz's
Philosophical Papers and Letters,
trans. Leroy Loemker
(Chicago, 1956). Standard editions of John Locke, Essay
Concerning Human Understanding;
Nicolas Malebranche,
Recherche de la vérité. J. S. Mill, System of Logic (London,
1949). Bertrand Russell, Human Knowledge (London, 1948);
idem, Mysticism and Logic (Garden City, 1957), “On the
Notion of Cause.” Moritz Schlick, “Gesetz Kausalität in der
gegenwärtigen Physik,” Die Naturwissenschaften (Berlin,
1931). Arthur Schopenhauer, Über die vierfache Wurzel...
(1813), trans. as The Fourfold Root of the Principle of Suffi-
cient Reason
(London, 1907). Benedict Spinoza, Ethics and
Correspondence, standard editions. A. N. Whitehead, Sym-
(New York, 1927); idem, Process and Reality (New
York, 1929).


[See also Analogy; Atomism; Causation in Islamic Thought;
Causation, Final Causes;
Chance; Dualism; God; Hege-
lian...; Indeterminacy; Necessity; Neo-Platonism; Pre-
Platonic Conceptions.]