Download Leibniz Discourse 8

MODERN PHILOSOPHY
LEIBNIZ’S DISCOURSE 8 - 16
What Is A Substance?
Aristotle on Substance
Comparison: Aristotle, Descartes, Leibniz
Motivations for Leibniz’s Theory of Monads
Facts About Monads
Why Matter Must Be Made Up Of “Mind-Like” Monads
Principle of Complete Concepts
Principle of Sufficient Reason (PSR)
Using PSR for the Principle of the Identity of Indisceribles
Using PSR to Prove God’s Existence
Creation and Destruction
Each Monad “Mirrors” the World
Why Monads Must have “Substantial Forms”
Necessity v Contingency in Leibniz’s Metaphysics
LECTURE
PROFESSOR JULIE YOO
WHAT IS SUBSTANCE?
Aristotle on Substance
One of the goals of metaphysics is to determine the most basic or fundamental stuff there is in
the universe. Some philosophers believe that substances are at the core of one’s inventory of
fundamental stuff. Other philosophers select a different ontological category, like “atoms.” In
the sciences, the most fundamental particles are quarks, leptons, bosons, and so on. For those
who chose substances as the most fundamental elements of the universe, they have in minds
something that can exist logically by itself if that thing can be coherently conceived WITHOUT
having to conceive of something else. It has a kind of INDEPENDENCE.
We should first get a grip on the idea of a SUBSTANCE, which philosophers use as a technical
term to designate a special kind of object. Not just any object can be a substance, in the
philosopher’s sense of the term.
S is a substance IFF
i. S can logically exist by itself, and
ii. S can take on properties, some contingent, some necessary.
For Aristotle, one of the pioneers of the idea of substances, the best representatives of substances
are living organisms like animals and plants. A cow, for instance, is a typical substance for
Aristotle. This is because a cow can be conceived independently of having to conceive of
anything else. What a cow needs physically is not the same as how the cow can exist logically.
Physically, a cow needs all sorts of things, like air, milk, grass, a pasture, a caring farmer, and so
on. But we need don’t have to conceive of these things when we conceive of a cow as a clear
idea in in our minds.
SUBSTANCES
•
•
•
a car
a cherry
a person
NON-SUBSTANCES
•
•
•
•
•
•
shininess (property)
owning a car (fact/a state of affairs)
an explosion (event)
the bruise on an elbow (modification)
a pile of laundry (mere heap)
hunk of gold (a mere mass)
Not just any object is a substance. Lots of thing can be called an “object.” In fact, the nouns and
noun phrases in our language allow us to pick things out as objects quite easily: Bessie’s smile,
your pile of laundry, the stuff in the back trunk of my car, a hunk of gold, a glass of water, the
bruise on your knee, the speed with which you won the marathon, … . None of these things,
however, counts as a substance in the philosopher’s sense.1
1
Different philosophers have different views about which things are actually substances. For someone like
Descartes, substances come in the form of God, individual minds (like your mind and my mind), and matter – all the
stuff that is a part of the physical world. For Descartes, even though matter can be chunked up into apparently
discrete packages of physical objects, like your body, my body, the cow, and so on, there is only ONE material
substance, and your body or my body are nothing but “modes” of that substance. This may sound kind of odd,
because many of us operate with a view that is more sympathetic to Aristotle, but we will later return to some of the
merits of a Cartesian view of physical substance. For now, just to get the ideas better placed in our grasp, we will
stick with Aristotle’s account of substance.
Brief Comparison on Substance: Aristotle, Descartes, Leibniz
Aristotle’s
Primary Substances
Descartes
Dualism
Leibniz’s
?Idealism?
•
living organisms
including humans
•
individual minds
and God
•
incorporeal monads
such has humans
•
artifacts
•
matter
•
corporeal monads
•
“form” in matter that
makes up a form/
matter compound
•
thought for mind
•
•
extension for matter
individual essence,
“haecceity,” that
contains the whole
history of the world
CANDIDATES FOR
SUBSTANCES
THEIR ESSENCES
TELEOLOGICAL
EXPLAINABILITY
•
all substances
•
minds
•
all monads
MECHANICAL
EXPLAINABILITY
•
N/A
•
bodies
•
the “phenomena”
expressed by
corporeal monads
MOTIVATIONS FOR LEIBNIZ’S THEORY OF MONADS
The things Leibniz says about substances, also called monads, sound pretty bizarre. To
appreciate what is going on, we need to cover some groundwork. A significant motivation for
Leibniz’s views on substance come from his theodicy, that the world in which we live is the best
of all possible worlds that God could have created. So first and foremost, Leibniz wants a theory
of substances that can support:
Leibniz’s views on the
a) his theodicy
b) why any other world is not the best
Another motivation is Leibniz’s dissatisfaction with:
Descartes’s views on the
a) inadequacy of extension as the essence of matter
b) Descartes’s difficulty explaining MB interaction
To give an account of things that avoid the problems faced by a Cartesian, Leibniz adopts some
of the views about the nature of a substance that go back to Aristotle. In particular, these are:
Aristotle’s views on the
a) necessity of “forms” or telos in a substance
b) indivisibility and unity of a substance
Leibniz wants to walk a tightrope that, on the one hand, maintains Descartes’s revolutionary
commitment to mechanistic explanations of PHYSICAL phenomena, while on the other hand,
fixes a deficiency in Descartes’s account of matter, which can only be remedied by appealing to
the Aristotelian notion of a telos. Towards that end, we get the following theses, principles, and
claims about the nature of basic substances/monads.
FACTS ABOUT MONADS
It should be noted that Leibniz worked on his theory of substances (monads) throughout his life
and changed his views somewhat as he matured. The view encasuplated in this lecture takes
material from his Discourse on Metaphysics as well as his Monadology.
Here, in a nutshell, is Leibniz’s view of monads:
• they are the fundamental ingredients that make up the things in the universe
• there are infinitely many monads
• indivisible (like atoms, but unlike atoms, are not physical)
• each monad contains the profile of every other monad, which collectively
portray the history of the world – God’s creation
• no two monads are alike; each has its unique nature or “haecceity”
• monads are “mind-like”
This is an admittedly wild set of claims. However, they work together to satisfy the motivations
listed above.
Why Matter Must Be Made Up Of “Mind-Like” Monads
The reason invokes the inadequacy of Descartes’s view that matter is nothing but extension. In
Discourse 12, Leibniz says that this is not a solid foundation for the new mechanistic explanation
of physical phenomena:
[T]here is more to the nature of body than extension (that is, size, shape, and
motion), and that we can’t avoid attributing to body something comparable with
a soul, something commonly called ‘substantial form’ … . (p. 236)
For Leibniz, mere extension cannot give us matter at all, because extension is infinitely divisible,
and matter that is based on infinite divisibility must vanish into infinitesimally non-existents. To
have matter, there must be something indivisible that makes the sizable matter possible. To get
matter, we need monads with substantial forms. In a different source, Leibniz makes the point
clear:
At first, after freeing myself from bondage to Aristotle, I accepted the void and
atoms, for it is these that best satisfy the imagination. But thinking again about
this, after much meditation I saw that it was impossible to find the principles of
a real unity in matter alone or what is merely passive, since this nothing but
collection or aggregation of parts at infinitum. Now, a multiplicity can derive its
reality only from true unities … . (NS, FW 145)
The stuff we see around is an aggregate of smaller bits of matter. But at the end of the day, these
bits have to come down to real things, not further divisible matter, where you would lose
substantiality and whittle everything down to nothing. You can’t get something out of nothing.
That something from which we get matter must be monads, and moreover, these monads must
have a substantial form, which amounts to having something like a mind – not a full human mind
that can make plans, speak language, do math, and other intellectual thing – but a mind
nonetheless. Why? Because only a mind can have a true unity!
Why can’t the constituents be physical? In other words, what is the argument for Premise (2)?
We can discern two arguments that support (2), a negative argument and a positive argument.
The negative argument can be formulated in terms of a dilemma:
Negative Argument
1. Either the constituents of matter are physical or they are mental.
2. The constituents of matter cannot be physical.
3. The constituents of matter must be mental.
The burden of this argument is supporting Premise (2). And for that, we get this argument:
2a. If the constituents of matter are physical, then their infinite
divisibility renders them into infinitesimal points that amount to no
matter at all.
2b. If their infinite divisibility renders them into infinitesimal points
that amount to no matter at all, then matter cannot exist.
2c. But matter DOES exist.
2. The constituents of matter cannot be physical.
Positive Argument
1. The constituents of matter must ultimately come down to unified
entities – substances.
2. Only minds are unified.
3. The constituents of matter are mind-like.
The support for Premise (2) of the Positive Argument echoes Descartes’s conviction that minds
are indivisible. Minds, of course, are teleological through and through. Hence, the retention of
telos in the account of the nature of monads.
Leibniz admits in Discourse 10 that appealing to Aristotelian telos in the account of monads
appears to be a step backwards. But he explains how, in fact, his view is not a resuscitation of the
Old Physics.
I agree that these forms have no work to do in explaining particular events, and
thus no role in the details of physics. That is where our scholastics went wrong,
and the physicians of the past followed them into error: they thought they could
invoke forms and qualities to explain the properties of bodies, without bothering
to find out how the bodies worked—like settling for saying that a clock’s form
gives it a ‘time-indicative quality’, without considering what that consists in—
that is, without considering what mechanisms are involved. (p. 236)
Here, Leibniz explains how one can draw a clear distinction between using telos to explain
physical phenomena, which he does not endorse, and using it to develop a metaphysics.
Appealing to telos in one’s metaphysics is totally different from appealing to it in one’s physics.
For Leibniz, a metaphysics with teleologically characterized substances supports a physics that
can proceed with mechanistic explanations.2
Principle of Complete Concepts
In Discourse 8, Leibniz says that each substance has a “complete concept.” A “complete
concept” is like a complete life story. This means that for each monad, m, everything true about
m, both intrinsically and relationally, can be captured by a concept that applies uniquely to m:
We can therefore say that the nature of an individual substance or of a complete
being is to have a notion so complete that it is sufficient to include, and to allow
the deduction of, all the predicates of the subject to which that notion is
attributed. (p. 234)
Leibniz analyses sentences in terms of a subject – the noun phrase that picks out the individual
we want to talk about – and a predicate – a verb phrase that describes or individual’s features or
actions. Of course we mortals do not know the life history of any individual completely, but
God knows it a priori:
God, who sees the individual notion or ‘thisness’ of Alexander, sees in it at the
same time the basis and the reason for all the predicates that can truly be said to
belong to him, such as for example that he would conquer Darius and Porus,
even to the extent of knowing a priori (and not by experience) whether he died a
natural death or by poison—which we can know only from history. (p. 234)
Each individual’s complete concept contains information about all the other individuals that are
interconnected to that individual; in fact, all the monads are connected with every other
(infinitely many) monads:
Furthermore, if we bear in mind the interconnectedness of things, we can say
that Alexander’s soul contains for all time traces of everything that did and signs
2
According to Aristotle’s theory of substances, a substance is a blend of two things: form and matter. Depending
on which form a chunk of matter takes on, that thing becomes an oak tree, a cow, or a human being. For each of
these kinds of substances, they have a form that determines their nature of essence, which is cashed out in terms of
their teleology: an oak tree has the goal of being an oak, a cow has the goal of being a cow, and a human being has
the goal of being a human being (a rational animal that can be ethically and politically sensitive). As we say,
teleological explanations invoke things like purpose, desire, goals, and intentions, whose satisfactions require protominds that store and execute these final ends – their telos. At the beginning in Discourse 11, he says:
I know I am putting forward a considerable paradox in claiming to rehabilitate the ancient
philosophy, in a way, and to re-admit substantial forms when they have been all but banished. But
perhaps you won’t just brush me off if you realize that I have thought a lot about the modern
philosophy, that I have spent much time on experiments in physics and proofs in geometry, and that
for a long time I was sure that these entities [substantial forms] are futile. (p. 236)
of everything that will happen to him—and even marks of everything that
happens in the universe, although it is only God who can recognise them all.
Principle of Sufficient Reason
The first sentence of Discourse 9 announced L’s famous yet controversial claim that no two
things are ever exactly alike. This is known as Leibniz’s Principle of the Identity of
Indiscernibles:
Several considerable paradoxes follow from this, amongst others that it is ·never·
true that two substances are entirely alike, differing only in being two rather than
one. (p. 235)
The reason for this claim comes from Leibniz’s commitment to another principle, namely:
Principle of Sufficient Reason (PSR): Everything has a reason or a
cause, or for every (contingent) fact, there is an explanation for
that fact.
Using PSR for the Principle of the Identity of Indisceribles
According to Leibniz, no two things are exactly alike because in creating two things that are
exactly alike, there is no reason for treating the one differently from the other. But every thing
has a reason, and there is no reason to treat alike things differently. Therefore, according to PSR,
no two things are exactly alike.
Using PSR to Prove God’s Existence
Leibniz uses PSR to justify a number of important claims, such as the existence of God, as well
as the Principle of the Identity of Indiscernibles. To establish that God exists, Leibniz argues
that the world is a collection of contingent beings. By the PSR, every contingent being calls for
an explanation or a cause. The only thing that can cause these contingent beings is God.
Creation and Destruction
In Discourse 9, Leibniz says there are only two ways things get created or annihiliated, and that
is through either:
A) God’s creation or annihilation of the individual monads.
B) Coming together of existing monads to create a larger
compound or the dissolution of the compound by the scattering
of monads.
It also follows that a substance cannot begin except by creation, nor come to an end except by
annihilation; and be- cause one substance can’t be destroyed by being split up, or brought into
existence by the assembling of parts, in the natural course of events the number of substances
remains the same, although substances are often transformed.
Each Monad “Mirrors” the World
This surprising claim is a restatement of Leibniz’s view that each substance has a complete
concept. In having a complete concept that not only tells the story about that individual
substance, but the relations of that substance to all other substances:
Moreover, each substance is like a whole world, and like a mirror of God, or
indeed of the whole universe, which each substance expresses in its own
fashion—rather as the same town looks different according to the position from
which it is viewed. In a way, then, the universe is multiplied as many times as
there are substances, and in the same way the glory of God is magnified by so
many quite different representations of his work. It can even be said that each
substance carries within it, in a certain way, the imprint of God’s infinite
wisdom and omnipotence, and imitates him as far as it can. (p. 235)
This is a dramatic and quite poetic paean to God’s creation.
Necessity v Contingency in Leibniz’s Metaphysics
The final puzzle to sort out in this view is how to distinguish necessary from contingent truths.
Towards this end, we have to distinguished between:
A) Absolute Necessity: Necessary truths whose contrary implies a
contradiction.
B) Hypothetical Necessity: Necessary truths whose truth depends
upon a prior assumption (like “Because God made it so … “),
whose contrary does not imply a contradiction.
Our world is full of events along the lines of (B). Only God and truths about him involve (A).