Philosophy of Mind (Intro)
What is the “Mind?”
Or
perhaps better…
What, if anything, is the mind?
Long Standing Controversy
Some Ancient Western Views:
·
Plato who insisted that people had immaterial psyches/souls that
survived bodily death.
·
Aristotle countered that separating mind and
body was like trying to pry an imprint from the imprinted wax.
Cartesian Dualism.
Identified
with René Descartes-
Cartesian Dualism: The metaphysical theory that there
are two different kinds of substances[1];
mind or “mental substance,” and body or “physical substance.” These different substances, though radically
different and ontologically independent, nevertheless interact with one
another.
Descartes,
in his quest reasoned for absolutely
certain beliefs which could act as the foundation of all human knowledge
engages in a process of methodological doubt.[2] Through this process he discovered that he
could doubt the existence of his body (Indeed he could doubt the reality all
that is known through the senses- i.e. physical reality.), but he
could NOT doubt his own existence. This
suggests that he is NOT identical to his body.
Further, he cannot doubt his existence as a “thinking thing” because in
the very act of doubting/thinking he was immediately and undeniably
aware of his own existence as a thinking agent (self-conscious).
Note: This is what lead him to his famous pronouncement “Cogito ergo sum.”
Therefore
the “I” of his “Cogito” was not the physical body.
Descartes
is using an axiom here, that if two things are identical, then they share all
the same properties.
Note: Leibnitz formalized
the “Principle of the Indiscernability of Identicals”
which states the common sense notion that if A is identical to B then all
things true about A are things true about B.
Or, alternatively, A is identical to B if and only if every property of
A is a property of B.
Consider
the following exchange:
Imagine
I told you that I grew up in
Well
then, I know that your father is not identical to the boy I went to school with.
Why? Because the boy I went to school with has a
property (State Cross-Country Champion) that you father does not.
Since Descartes
thinks his body has a property (is doubtable) that his mind (mental life) does
not share, the two are not identical. He
(the thinking “I” of the Cogito) is not his/a body. His identity was as a "thinking thing," in other words, a
mental substance. It also leads him to conclude various things about the nature
of thinking and mind.
One
could intelligibly doubt the existence of one’s body, but NOT one’s mind. It follows then that the mind and body are NOT
identical since one has a property that the other lacks.
FROM
"MEDITATION VI" BY RENE DESCARTES
Firstly,
then, I perceived that I had a head, hands, feet, and other members composing
that body which I considered as part, or perhaps even as the whole, of myself.
I perceived further, that that body was placed among many others, by which it
was capable of being affected in diverse ways, both beneficial and hurtful; and
what was beneficial I remarked by a certain sensation of pleasure, and what was
hurtful by a sensation of pain. And, besides this pleasure and pain, I was
likewise conscious of hunger, thirst, and other appetites, as well as certain
corporeal inclinations towards joy, sadness, anger, and similar passions.
Nor
was I altogether wrong in likewise believing that that body which, by a special
right, I called my own, pertained to me more properly and strictly than any of
the others; for in truth, I could never be separated from it as from other
bodies: I felt in it and on account of it all my appetites and affections, and
in fine I was affected in its parts by pain and the titillation of pleasure,
and not in the parts of the other bodies that were separated from it. But when
I inquired into the reason why, from this I know not what sensation of pain,
sadness of mind should follow, and why from the sensation of pleasure joy
should arise, or why this indescribable twitching of the stomach, which I call
hunger, should put me in mind of taking food, and the parchedness of the throat
of drink, and so in other cases, I was unable to give any explanation, unless
that I was so taught by nature; for there is assuredly no affinity, at least
none that I am able to comprehend, between this irritation of the stomach and
the desire of food, any more than between the perception of an object that
causes pain and the consciousness of sadness which springs from the perception.
And in the same way it seems to me that all the other judgments I had formed
regarding the objects of sense, were dictates of nature; because I remarked
that those judgments were formed ii me, before I had leisure to weigh and
consider the reasons that might constrain me to form them.
But,
afterwards, a wide experience by degrees sapped the faith I had reposed in my
senses; for I frequently observed that towers, which at a distance seemed
round, appeared square when more closely viewed, and that colossal figures,
raised on the summits of these towers, looked like small statues, when viewed
from the bottom of them; and, in other instances without number, I also
discovered error in judgments founded on the external senses; and not only in
those founded on the external, but even in those that rested on the internal
senses; for is there aught more internal than pain? and yet I have sometimes
been informed by parties whose arm or leg had been amputated, that they still
occasionally seemed to feel pain in that part of the body which they had
lost,—a circumstance that led me to think that I could not be quite certain
even that any one of my members were affected when I felt pain in it. And to
these grounds of doubt I shortly afterwards also added two others of very wide
generality: the first of them was that I believed I never perceived anything
when awake which I could not occasionally think I also perceived when asleep,
and as I do not believe that the ideas I seen to perceive in my sleep proceed
from objects external to me, I did not any more observe any ground for believing
this of such as I seem to perceive when awake; the second was that since I was
as ye ignorant of the author of my being, or at least supposed myself to be so,
I saw nothing to prevent m) having been so constituted by nature as that I
should be deceived even in matters that appeared t me to possess the greatest
truth.
... because, on
the one hand, I have a clear and distinct idea of myself... as... only a
thinking and unextended thing, and as, on the other
hand, I possess a distinct idea of body ... only an extended and unthinking
thing, it is certain that I am entirely and truly distinct from my body, and
may exist without it.
Decartes was a man of science and mathematics.
(A point often missed- He was among the first anti-anamists and championed a naturalistic reductionism.)
·
People's
bodies, he claims, are machines.
·
He
would have liked, on some levels, to say the same about minds.
·
But
introspection and reflection reveal that reduction of “mind” to physical items
is inadequate.
·
Mind
(mental substance) has unique properties unshared by physical substance.
·
We
must posit a separate substratum to house the (uniquely) mental properties.
Properties of Mind
“The
Mental” was (uniquely)
1.
private (privileged access)
2. no
position in space
3.
something whose contents cannot be gainsaid (incorrigible)
4.
known to you directly (privileged access)
5. has
a distinct, subjective feel
But
Descartes cannot deny that the mind is “fused” to a body, at least for the time
being.
This
raises a puzzle: Specifically, what is
so special about this body so as to call it “mine?”
(How is it so intimately connected to this mind?)
FROM
"MEDITATION VI" BY RENE DESCARTES
But
now that I begin to know myself better, and to discover more clearly the author
of my being, I do not, indeed, think that I ought rashly to admit a which the
senses seem to teach, nor, on the other hand, is it my conviction that I ought
to doubt in general of their teachings.
And,
firstly, because I know that all which I clearly and distinctly-conceive can be
produced by God exactly as I conceive it, it is sufficient that I am able
clearly and distinctly to conceive one thing apart from another, in order to be
certain that the one is different from the other, seeing they may at least be
made to exist separately, by the omnipotence of God; and it matters not by what
power this separation is made, in order to be compelled to judge them
different; and, therefore, merely because I know with certitude that I exist,
and because, in the meantime, I do not observe that aught necessarily belongs
to my nature or essence beyond my being a thinking thing, I rightly conclude
that my essence consists only in my being a thinking thing [or a substance
whose whole essence or nature is merely thinking]. And although I may, or rather, as I will
shortly say, although I certainly do possess a body with which I am very
closely conjoined; nevertheless, because, on the one hand, I have a clear and
distinct idea of myself, in as far as I am only a thinking and unextended thing, and as, on the other hand, I possess a
distinct idea of body, in as far as it is only an extended and unthinking
thing, it is certain that I [that is, my mind, by which I am what I am] am
entirely and truly distinct from my body, and may exist without it.
But
there is nothing which that nature teaches me more expressly [or more sensibly]
than that I have a body which is ill affected when I feel pain, and stands in
need of food and drink when I experience the sensations of hunger and thirst,
etc. And therefore I ought not to doubt but that there is some truth in these informations.
Nature likewise teaches me by these sensations of pain,
hunger, thirst, etc., that I am not only lodged in my body-as a pilot in a
vessel, but that I am besides so intimately conjoined, and as it were
intermixed with it, that my mind and body compose a certain unity.
For if this were not the case, I should not feel pain when my body is hurt,
seeing I am merely a thinking thing, but should perceive the wound by the
understanding alone, just as a pilot perceives by sight when any part of his
vessel is damaged; and when my body has need of food or drink, I should have a
clear knowledge of this, and not be made aware of it by the confused sensations
of hunger and thirst: for, in truth, all these sensations of hunger, thirst,
pain, etc., are nothing more than certain confused modes of thinking, arising
from the union and apparent fusion of mind and body.
Besides this, nature teaches me that my own body is
surrounded by many other bodies.... some are agreeable, and others
disagreeable, there can be no doubt that my body, or rather my entire self, in
as far as I am composed of body and mind, may be variously affected, both
beneficially and hurtfully, by surrounding bodies.[3]
So
then, the person is essentially an immaterial mind (soul) which happens for a
time to be wedded to, but is nevertheless ontologically distinct from, a body.
If and when the body is destroyed, this union is dissolved and the mind will
continue to exist disembodied. (And the
body will exist “unsouled.”
Descartes
acknowledges that our mental activities and the movements of our bodies are
coordinated and must be accounted for.
Remember,
Descartes posits not only mind/body dualism, but mind/body interactionism.
Interactionism- mental changes cause bodily changes
and vice versa.
Cartesian Dualism Has Certain
Religious/Metaphysical Attractiveness:
1. It makes sense of the thesis that the soul might survive
the body after death (religious belief in afterlife affirmed).
2. It separates autonomous realms of religion and science.
(Remember Galileo was his contemporary and the future relationship between
science and the Church appeared to be rocky.)
3. It even provides an argument for the necessity of God's
existence. (Descartes points out (in Meditation III) that his various fleeting
thoughts could not be unified into a coherent, enduring self without the
intervention of a higher power.[4])
4. Provides a basis for (underdetermined) free will and thus
personal responsibility.
5. It affirms the unique and privileged status of humans.
(Distinguishes that which is “natural” and that which is “artifact”)
6. Provides a basis for resolving puzzles about personal
identity (and again, personal responsibility)
7. Consistent with the notion of “Supernatural” agency at
work in the world.
And in
the dedication of the Meditations, he
writes,
“And as to the soul: although many have regarded its nature
as incapable of easy inquiry, and some have gone so far as to say that human
reasoning convinces them that the soul dies with the body, and that the
contrary is to be held on faith alone; nevertheless, because the Lateran
Council under Leo X, in Session 8, condemned these people and explicitly
enjoined Christian philosophers to refute their arguments and to use all their
abilities to make the truth known, I too have not hesitated to go forward with
this.”
#2 Mysteriousness of Consciousness
#3 Lurking Homunculi
#4 Conservation of Energy Principle
#5 Mysteriousness of Ontological Status
of “Interactions”
Problems with Cartesian Dualism:
How
can two things as substantially different as Cartesian Mind and Cartesian Body
interact. As was put to Descartes
himself: “Where does the mind touch the
body.”
FROM
"THE PASSIONS OF THE SOUL" BY DESCARTES
But in order to understand all these things more perfectly,
we must know that the soul is really joined to the whole body, and that we
cannot, properly speaking, say that it exists in any one of its parts to the
exclusion of the others, because it is one and in some manner indivisible,
owing to the disposition of its organs, which are so related to one another
that when any one of them is removed, that renders the whole body defective;
... the soul is really joined to the whole body, and... we
cannot, properly speaking, say that it exists in any one of its parts to the
exclusion of the others ...
and because it is of a nature which has no relation to
extension, nor dimensions, nor other properties of the matter of which the body
is composed, but only to the whole conglomerate of its organs, as appears from
the fact that we could not in any way conceive of the half or the third of a
soul, nor of the space it occupies, and because it does not become smaller
owing to the cutting off of some portion of the body, but separates itself from
it entirely when the union of its assembled organs is dissolved.
It is likewise necessary to know that although the soul is
joined to the whole body, there is yet in that a certain part in which it
exercises its functions more particularly than in all the others; and it is
usually believed that this part is the brain, or possibly the heart: the brain,
because it is with it that the organs of sense are connected, and the heart
because it is apparently in it that we experience the passions. But,
in examining the matter with care, it seems as though I had clearly ascertained
that the part of the body in which the soul exercises its functions immediately
is in nowise the heart, nor the whole of the brain, but merely the most inward
of all its parts, to wit, a certain very small gland which is situated in the
middle of its substance and so suspended above the duct whereby the animal
spirits in its anterior cavities have communication with those in the
posterior, that the slightest movements which take place in it may alter very
greatly the course of these spirits; and reciprocally that the smallest changes
which occur in the course of the spirits may do much to change the movements of
this gland.
Let us then conceive here that the soul has its principal
seat in the little gland that exists in the middle of the brain, from whence it
radiates forth through all the remainder of the body by means of the animal
spirits, nerves, and even the blood, which, participating in the impressions of
the spirits, can carry them by the arteries into all the members. Recollecting
what has been said above about the machine of our body, that is, that the
little filaments of our nerves are so distributed in all its parts, that on the
occasion of the diverse movements which are there excited by sensible objects,
they open in diverse ways the pores of the brain, which causes the animal
spirits contained in these cavities to enter in diverse ways into the muscles,
by which means they are capable of being moved; and also that all the other
causes which are capable of moving the spirits in diverse ways suffice to
conduct them into diverse muscles; let us here add that the small gland which is the main seat of the soul is so suspended
between the cavities which contain the spirits that it can be moved by them in
as many different ways as there are sensible diversities in the object, but
that it may also be moved in diverse ways by the soul, whose nature is such
that it receives in itself as man diverse impressions, that is to say, that it
possesses as many diverse perceptions as there are diverse moments in this
gland. Reciprocally, likewise, the machine of the body is so formed that
from the simple fact that this gland is diversely moved by the soul, or by such
other cause, whatever it is, it thrusts the spirits which surround it towards
the pores of the brain, which conduct them by the nerves into the muscles, by
which means it causes them to move the limbs.[5]
Q: How (where) does the Soul (mind) “touch” the Body?
Descartes’ A: The Pineal Gland!
But…
·
Descartes
“solution” doesn’t really answer anything.
·
Problem
remains in the form: “Where does the Soul (mind) touch the Pineal Gland?”
Remember:
Mind
is defined
as "unextended"
Bodies
are defined
as extended in space.
Minds,
by
definition, are essentially unlike bodies. (Cannot be said to be
"large" or located in such and such a place.) Interaction would seem to be ruled out by
definition.
Note: despite this definition, notice how
much of our talk about consciousness consists of metaphors of spatial
form: "stream of consciousness. “out of his mind”, “what I’m feeling
inside,” etc.")
Question then:
How
can minds (whatever they are) affect bodies (whatever they are)?
One’s
physiology can explain some bodily activities.
e.g. nerves are pinched and signals are sent through your
central nervous system into that huge complex of fat cells called your brain.
But
then, at some point, there seems to be something else, the feeling, the pain.
How
does this happen? How does a feeling emerge from that complex and still unknown
network of neurological reactions going on in your body?
Even
if you don't want to talk of substances at all, there is still the problem of
explaining how your mind affects your body and how your body affects your mind.
Note: Beware of trying to describe the soul
in terms such as “energy.” Energy has at
least some of the intangible and amorphous features of mind. (has no size or
weight) But energy is a function
of physical bodies, (“Force is a function of mass and acceleration.) energy is not "private" not do we
have privileged or incorrigible access to energy.
While it has been demonstrated that energy and mass are
inter-convertible, any such "interconvertibility"
of mind and matter is still at the highly speculative stage.
If we talk
about "mental energy," it is far from clear what we mean.
Problems with Cartesian Dualism:
#2 Mysteriousness of Consciousness
Cartesian
Dualism suggests that consciousness is essentially elusive and mysterious. It will always be beyond the ability of science
to explain or account for. (Supernatural)
Further, while consciousness is always inaccessible to science, all but
one’s own consciousness is inaccessible period.
Note: We describe a pain, etc. with
metaphors or comparisons – not clear how else we could: ("It's as if a
vice were closing on my head.") ("It feels the same as when
..."). There is, in both cases a
reliance on the subjective experience in the hearer in order to communicate the
content.
In
fact, the inaccessibility to the subjective experience of others suggests the:
Problem of Other
Minds:
While (arguably) I can know that I have conscious experience (a mind), how can
I be sure anyone else does? How can I be
sure that they are not zombies?
So
1. I
can't know or describe your mind at all.
2. I
have difficulty describing my mind.
This
difficulty to know or describe Mind with any real objective precision has lead
some psychologists and philosophers to reject the term completely. They suggest that the our talk of
"mind" is inherently confused and in truth refers to no one thing. They prefer to talk about only what is
mutually observable and "extended" in physical space (for example,
neurology and overt behavior).
Descartes
would claim then that these individuals are missing out on half of reality.
Note: The idea of “mind” and “mental talk”
can be more easily rejected with reference to other people than it can be with
reference to ourselves because, after all, "I am thinking" and
"I exist as a thinking thing".
In one's own case, the fact that a person is self-conscious (it would
seem) is the last thing one could ever deny- literally :-).
Problem with Cartesian:
Dualism #3 Lurking Homunculi
How is
consciousness connected to your body?
One might
imagine a little man or woman in your head (or perhaps more than one),
operating your body the way you might operate the controls of a robot. But this model is fatally flawed. Who or what is inside the “little person’s”
head pulling the levers? Philosophers
refer to the weakness of this view by claiming such a model relies on an Homunculus;
one is positing another mind (a little person) to explain how your mind works. But that doesn’t explain it, it just pushes
it back one mind. If there were a little
person inside you, that person would face the same problem.
Additionally,
neuroscience seems to indicate that there is no single “seat of consciousness.”
(There is no little person.) Consciousness
seems to depend on (if not be identical to) independently functioning modules
distributed across the brain.
Problem with Cartesian Dualism:
#4 Conservation of Energy Principle
Interactive
Dualism seem to violate the Conservation of Energy principle from physics.
Conservation of
Energy: The
principle that energy cannot be created or destroyed, although it can be
changed from one form to another; no violation of this principle has been
found. Also known as energy conservation.
A
corollary to this is that there cannot be non-physical forces of energy. But Cartesian Dualism seems to postulate
precisely that: non-physical sources of “physical activity” (i.e. How is Patrick Swasey
character able to push the penny in the film “Ghost?”)
#5 Mysteriousness of Ontological Status
of “Interactions”
These
“interactions” would be even more mysterious and inaccessible than mind. Whatever the exchange between bodies and
minds, they could not be material processes since it involves mind. This means they are not public and
inaccessible to science. But they could
not be immaterial processes since it involves matter. This means that they are not private and
inaccessible to introspection.
What
is the ontological status of these interactions. Is it some third status? Neither material nor immaterial? But wouldn’t that just make things worse?
Early Attempts at Resolution of the
Mind/Body Problem:
Baruch (or Benedictus)
Spinoza (1632-1677)
Spinoza
held the position that the mental and the physical are simply two “modes” of a
more basic substance. For Spinoza
“substance’ exists but can be known as physical or as mental. Despite the fact that substance can be
apprehended in these very different ways, the ways in don’t interact. The substance just “is” and the appearance of
two interacting autonomous substances is an illusion. For Spinoza, this only substance was God/
Nature/ Reality. (Deus Sive Natura) Thus the only real thing is God.
Problem:
Gottfried Leibniz (1646 –1716):
Leibniz
develops a comprehensive theory of monads, -bit is psychic force we
might say.
Insisted
that there could be no causal interaction between monads whatsoever
Denied
that mental substances interacted with anything that we call "physical
bodies."
Claimed
that God, who had created monads in the first place, had also created them in
such a way that mental activities of each are coordinated to reflect the
activities of each other.
Doctrine
of "Pre-established Harmony"
Pre-established Harmony: Leibniz’s theory that Monads, each
being singular substances, do not interact.
Rather, God, who had created monads in the first place, has created them
ins in such a way that mental activities of each are coordinated to reflect the
activities of each other.
More Recent Attempts at Resolution of
the Mind/Body Problem:
Recent (last 100 years or so) Philosophers have
proposed a number of solutions.
All of
them controversial.
Sort-of Side-Stepping Dualism: Dual
Aspect Theory
William James (1842 – 1910) Sort-of
Rejection of Dualism: Epiphenomenalism
Mental
events are epiphenomena
caused
by physical events (but not identical to physical events).
They,
have no causal powers of their own.
The
view allows for causal interaction, but only in one direction.
Think
of a boiler with a temperature gauge. The boiler’s temperature causes the gauge
to behave in a certain way. But notice
that doing something to the gauge will not affect the machine at all. One cannot change the temperature of the
boiler by adjusting the needle of the gauge.
In effect, the gauge is irrelevant to the working of the machine.
This view
preserves the continuity of physical laws without the problematic disruption of
non-physical "mental causes." (Conservation of Energy- sort of since
it might predict some energy lost from the system.)
Further,
researchers can need only to concentrate the physical side of the matter to
explain why the world is and behaves as it is and does, and they may ignore
"the mind" completely.
Problems with this view:
1.
Still have interaction problem.
2. No
evolutionary explanation for consciousness.
3.
Can’t tell sentient humans from zombies.
Perhaps
the answer is the rejection of dualism.
Bertrand Russell (1872 – 1970) (Trying
to Stay Out of the Dualism Debate)
Defended
a version Spinoza's theory without reference to the metaphysical notion of
substance.
mental
events and physical changes are different aspects of the same
"something."
our
experiences and ideas were one aspect of some events or activities of which the
various chemical reactions of the brain were another aspect.
Problem
But
this does really seem to solve the problem.
·
What
is
this mysterious "something" of which mind and body are merely
"aspects"?
·
How
could one and the same thing have such different aspects?
·
Not
obvious that more biological facts will make this any more clear. Actually, seem to perpetuate the
“mysteriousness of consciousness” problem.
·
Even
when we have complete "brain maps" and can say for every mental
occurrence what is going on in the brain at the same time, the problem will
still remain; How/why are the two related?
The Rejection of Dualism Itself: Idealism
(George Berkeley 1685 – 1753, et alia)
Idealism is the metaphysical position that
there is only one kind of substance (Monism) and that substance is mental. Alternatively it is the view that the only
things which exist are ideas and the minds that perceive them. It follows from
this view then that what we call physical objects are really just (complex)
ideas. (Keep in mind that walls are still “solid” so don’t get any ideas about
walking through them.)
Problems
Difficult
to explain “non-perceived” reality.
Calls
into the question the very notion of a “substance” anyway.
The (Outright) Rejection of Dualism
Itself: Physicalism
Physcialism is the metaphysical position that
there is only one kind of substance (Monism) and that substance is
physical. Alternatively it is the view
that the only things which exist are physical objects and physical forces. It follows from this view then that either
minds are physical (objects, forces, or operations of physical objects and
forces) or they do not exist at all.
Philosophers
of recent years—and nearly all psychologists—have taken a dim view toward
dualism in any form. They have sought a
resolution the mind/body problem consistent with physical.
[1] Named after Descartes. As a matter of fact, Descartes believed that there were three kinds of substances, the third being God. But we need not worry about that third substance at this point. For our purposes, Descartes is simply a dualist.
[2] He does this in perhaps his more influential work” Meditations on the First Philosophy. Contrary to philosopher who processed him, he suggests that the “first” set of philosophical questions that need to be addressed are NOT metaphysical questions (What exists?), but rather epistemological questions (What can/ do we know?) . This ushers in what has come to be called “the epistemic turn” in the history of philosophy.
[3] 'Rend Descartes, "Meditation
VI," in Meditations on First Philosophy, in The Philosophical Works of
Descartes, trans. Elizabeth S. Haldane and G. R. T. Ross (Cambridge: Cambridge
University Press, 1911).
[4] Because the entire period of one's
life can be divided into countless parts, each of which in no way depends on
the others, it does not follow from the fact that I existed a short while ago
that I now ought to exist, unless some cause creates me once again, as it were,
at this moment—that is to say, preserves me. For it is obvious to one who is
cognizant of the nature of time that the same force and action is needed to
preserve anything at all during the individual moments that it lasts as is
needed to create that same thing anew—if it should happen not yet to exist. It
is one of those things that is manifest by the light of nature that preservation
differs from creation solely by virtue of a distinction of reason.
Therefore
I ought now to ask myself whether I have some power through which I can bring
it about that I myself, who now am, will also exist a little later? Because I
am nothing but a thing that thinks—or at least because I am now dealing only
with precisely that part of me that is a thing that thinks—if such a power were
in me, then I would certainly be aware of it. But I observe that there is no
such power; from this fact I know most evidently that I depend upon a being
other than myself.
Rene
Descartes, "Letter of Dedication to the Dean and Doctors of the Faculty of
Sacred Theology of Paris," in Meditations
on First Philosophy, trass. Donald A. Cress
(Indianapolis: Hackett, 1979).
[5] Rene Descartes, "The Passions
of the Soul," in The Philosophical
Works of Descartes.
The
gland Descartes is referring to is what is now called the Pineal Gland, a small
endocrine gland at the base of the brain. It had only recently been discovered
in Descartes's time, and its functions are still not adequately understood. It
is currently hypothesized that it controls mating cycles in higher animals and
possibly any number of other activity cycles.