To understand David
Hume's criticism of the idea that we can know, in a robust and
philosophical way, that there is a connection between what we call
causes and effects, we must first examine how he thought our minds
related to the world. Unlike the Rationalists that came before him,
Hume was skeptical that reason and intuition were all that we needed
for knowledge. For Hume, the first contact that we have with any
object (if it exists at all) is the appearance the object has on our
senses, so that the first thing that we are aware of is an impression
that we have.1
Humean impressions are not simply limited to our sensual perceptions
of the potential objects around us, but are also of every possible
thing that we might experience, including our own internal mental
processes, like emotion-states and first-order desires. Impressions
are not just what we see, feel, taste, etc., but how we feel, what we
want, and what motivates us. In short, impressions are the way that
we first experience everything.
From
those impressions, content is directly added into the mind and
forms
ideas
that share
the same content.
Hume thought this was a matter of common sense, anyone could see that
while reflecting upon the painful experience of touching a burning
hot object, we almost feel the same pain, but with less force than if
we were actually touching something hot.2
To Hume, the impression had a strength to it that could never be
matched by a mere idea, but impressions only differed from ideas in
strength; the content was copied directly into the idea exactly as it
was in the impression.3
Once
a series of impressions has formed a series of ideas, the imagination
tends to form perceived connections between the ideas, and those
connections can be evaluated according to any number of relationships
they bear to each other.4
The comparative work is not a function of perception, but of
imagination, and as such, it cannot involve working with impressions,
but only with ideas. Of all possible relations, Hume thought that
they fell into seven broad groups: resemblance, identity,
space and time, quantity, quality, contrariety, and
cause and effect.5
From the comparison of ideas, the imagination then sorts the ideas
in a way that allows us to make sense of the impressions we receive.
For
instance, my ability to make sense of the world is dependent on my
imagination's ability to run freely across all ideas that I have,
compare them, and link ideas together when they meet one or more of
the relationships.6
If a series of impressions of red spherical objects strikes upon my
mind, the content is copied into identical but weaker ideas, and my
imagination draws comparisons between each new idea and every similar
idea from my memory. Each idea contains an object that is both red
and round, all of the ideas might be of the same object. I have
memories of similarly round objects in a wide variety of colors, they
did not occur at the same time or in the same place, so I imagine
that I'm viewing different, but similar objects. After surveying the
relevant relations, I conclude that I am viewing a group of red
balloons, a color and a term I learned sometime previous.
In
fact, I cannot have a previous idea of a balloon or the color red
unless I experienced them at some time before, in the same way that I
couldn't have a good idea of what a pineapple tasted like unless I
tasted it.7
Of course, the impressions I received would then become an idea
about the red spherical objects in the same way that the taste of an
exotic fruit becomes a just
idea when I taste it. However, even if my ability to reason
was absolutely perfect, if I did not have previous experience to draw
upon, it would be impossible for me to know anything beyond the
simple impressions that struck upon my senses.8
I would not be able to look at the balloons and draw any conclusions
about what would happen if I loosed them from their anchors; I could
not guess that they would float upward.
Because
all ideas are copies of impressions, the cause of all ideas is direct
impressions. While this might give an empirical legitimacy to the
content of ideas, it does open them to questions that Hume raised
about the nature of cause and effect, and that has a bearing on every
potential experience that we might have. If we exclude the
relationship of cause and effect, we only have a series of ideas and
memories that do count as evidence of objects, but do not allow us to
understand anything about the objects.9
Hume
argued that only by the relation of causality can an observer move
beyond the simple idea of two objects or events that appear one after
the other, e.g., the first time viewing a released balloon floating
upward there is no way to conclude anything.10
Only by repeatedly releasing balloons can we conclude that by
releasing the balloon (which we will call the cause)11,
it will float away (which we will call the effect). By repeating
this, we might believe that we have an understanding of a cause and
an effect, but no matter how many balloons we release, we can never
see any connection between
releasing a balloon and it floating up, we only see that one event
follows the other and they seem to be continually joined in our
impressions, ideas, and memories.12
Since
we are unable to have a direct impression of the connection, we are
unable to copy it into our ideas, or
any notion of powers like the necessary and customary connections
between causes and effects.13
We can only imagine and
infer that a connection
between them exist. If we
try to use reason alone to identify an ultimate connection between
causes and effects in general, reason will fail us because all we
have is experiences of
individual instances where it appears to us that there is a constant
conjunction between objects, but we
are not justified in saying that we know that it will hold for things
that are outside our experience.14
Kantian
Revolution
Immanuel
Kant's use of information gained by the senses is not so different
from Hume's, but there are notable differences in the grounds that
Kant uses to justify the inference from the senses to experience.
While having direct empirical, a posterriori
(reasoning from observation)
experience of an object does
give us the beginnings of all
understanding, Kant argued that trying to derive a universal law that
governed the connection we believe is
needed between cause and effect from frequent associations in the
experience, is a mistake that
would, as Hume pointed out, leave us with no justifiable reason to
think there is such a law.15
If experience is what justifies the rules that govern experience,
that means that the laws we'd hope universal are merely contingent on
the senses, and are not certain at all.16
To find such a universal law
requires the use reason to move beyond the limitations of experience
by using
pure
reason,
i.e.,
objective rationality that is beyond the individual as
in mathematics and the sciences,
to
shift the focus
beyond what is
possible with practical
reason and sensations,
even beyond the objects that present to
us.17
The
major departure from Hume's position is that Kant held both the
Rationalist view of the intuition and the Empiricist view of the
senses as the source of knowledge. While these two seem to be at
odds, Kant shows that they are both necessary for
actually
being able understand
any possible object we might experience. His system begins with
space.
More
specificity, it begins with any given observation of an object, when
stripped of all the empirical information so that we are no longer
able to consider any aspect that can
give an impression of
the object to us, we are left
with at least one property, the space that it occupied.18
Although
Hume
used space as a
relation the imagination uses to compare objects, there
are
conceptual issues with this view.
Since we cannot see space, we cannot copy an impression into our
ideas, and so it would not be an object of a posteriori experience.
By
removing the empirical data from an object, Kant leaves only the
space that the object occupied, implying that space is a
non-empirical property of the object, the
concept of which must come from the grounds of a priori
(reasoning from previous
grounds, lit. “from the former”)
judgments.19
Kant does not abandon the
Humean use of the concept of space as a relationship that allows us
to make determinations about the outside world, but uses that very
notion to begin exploring the concept of space. Before we are able
to examine any spacial relations between objects and ourselves, we
first have to conceive of the objects as exterior to ourselves, and
all possible objects, including
us,
to be inside a general space.20
This is the a priori
grounds from which we build the notion of separable spaces that each
object occupies.
While
not an object of empirical observations, space is the basis of all
experience in that we use the concept to show that two objects are
unique because they appear in two different places, and space is
necessary and a priori in
that we can not conceive of an object without space, but we can
conceive of space
without objects.21
Likewise, time
is an a priori foundational
concept that roots our perceptions of things
existing in the same moment, and gives us the successions of
sensations.22
Space and time, sharing very similar intuitive properties, are forms
of the way we perceive all of our sensations.23
Seeing that these a
priori notions are particular to
us, as humans, and may not hold for other beings, they form
pure intuitions that are necessary for our
a posteriori cognition
to be possible.24
When
I see a group of roughly spherical red objects, it is not just that
my imagination runs over all the ideas from my memories, it is that I
see them at different points in space, containing a different subset
of space, and all at a particular time. I can not even begin to have
an impression of them without first having the a priori
notions of space and time.
However, the balloons
do not contain the notions of space or time, they are in
space and time, and that
temporal-spacial reference is both outside of myself and distinct to
the objects.
Regardless
of how similar my empirical perceptions of them are, I can know that
they are not the same balloon repeated in my perception, because they
are in different points in space at the same time. If I did not
bring this a priori concept
with me, there is no possible way that I could ever have anything
that approaches
understanding, or cognition,
of the group of balloons. My
a priori notion of
space and time are the forms that allow me sensual experience.
Nonetheless,
I can not perceive either space or time, but must use pure reason to
reach these notions, and then I must force my observations to conform
to them. Kant called this a
revolution, in the tradition
of Copernicus, that reason should be taught by nature, but not as a
student that stumbles into knowledge, but as a judge that compels
nature to answer the questions necessitated by the laws pure reason
proves must exist.25
Hume's method (as well as
all philosophers engaged in any form of metaphysics) of
trying to see the power of
causality was merely groping among concepts.26
As
with space and time, in order to “see” causality, the philosopher
must first show it to be a possibility. In
a similar fashion to how jurists ask what is lawful and what are the
facts, Kant
separates
the matter into transcendental
deduction, which is
concerned with the a priori objects
in and of themselves, and the empirical
deductions that are
concerned with what is learned from experience.27
Space and time serve as a
demonstration of the division between the transcendental and the
empirical as we arrive at those concepts, which are the form of our
sensibility that are necessary for the possibility of understanding,
without borrowing any content from experience; any deduction of them
must be transcendental.28
In
an almost direct response to Hume's problem of induction, Kant
established a dichotomy of the possible ways that the objective
validity of cause and effect might be dealt with, either follow
Hume's course to the logical end and abandon it as a fantasy, or
follow the example of the concepts of space and time, and ground
causality completely on a priori
understanding.29
By taking the meaning of
cause and effect and producing a deductive rule that states that one
object follows from another,
i.e., is necessitated by another, we have an a priori
rule that has a universality that can not be matched by empirical
means.30
This is not to say that such a relationship does exist in reality,
only that it is “legal”. It allows us to subsume any empirical
observations of that form under a category, whereby we can properly
cognize the event.
If
I observe that by cutting the string that held down a balloon, that
it floats away, I take the series of impressions in my mind,
referenced with the forms of space and time, and bring them under the
transcendental categories, then I might be justified in saying that I
cognized, or understood, that the immediate cause of the balloon
floating upward was the cutting of the string. However, I think this
hints at a potential
weakness in Kant's model. While I might rightly conclude that I have
understood something about the world, I have not truly grasped the
full nature of what I have witnessed, in
and
of itself.
Kant
focuses on how it is possible for us
to have cognition of objects, things in themselves,
but it is conceivable that many truths about the world are beyond the
limitations of human observations (or at least the current limits)
and therefore beyond understanding and experience.
While he does provide a
possible way for us to justify empirical experience using a
priori forms, we have no way of
knowing if those forms actually represent anything real, or if our
limited ability to reason has somehow missed a form that does exist.
What I have missed is that
the string did not cause the balloon to float at all, but the
ultimate cause was the
relationship among
the lighter-than-air gas in the balloon, the atmosphere, and
gravity; the cutting of the
string was only an intermediate cause, but without experience with
gases and gravity, I am like Hume's Adam unable to know that water
will drown him.
Still,
I think Kant would reply that all that has happened was that I failed
to properly cognize this situation because I was unaware of hidden
causes that are fully possible in complex situations. Hidden
causes and failed cognitions
do not work against the a priori
category of causality and dependence because they do not show that
the category is impossible. We
neither need to posses all possible forms, only the necessary ones
for cognition to be possible, nor do the forms that pure reason has
defined need to align with objects in the world for them to be
potentially real. We cannot have cognition if we cannot place
objects into the categories, and we cannot have justified experience
if we do not have a priori
means of understanding. However,
much like the forms of space and time, if we are to have any
experience that includes cause and effect, then we cannot be without
the transcendental category.
Hume's
challenge was to how we could be rationally justified in concluding
that we understood cause and effect. Kant showed that there are
concepts that we cannot know except from a priori
grounds, and included in those is causality. The concepts do not
count as experience, but without them we can't begin to understand
the objects to which they should apply. Only after we have brought
the pure concepts together with the sensual impressions of an event
can we possibly have experience of them. In
this way, Kant provides the basis of possible experience of cause and
effect, and a rational method to say that as long as we have
justified means of understanding space and time that we do have
justification to conclude that we can understand cause and effect,
but only after we have
properly subsumed a causal event into the transcendental categories
can we have experience of it.
Bibliography
Hume,
David. A Treatise of Human Understanding. Ed.
David F. Norton and Mary J. Norton. Oxford: Oxford University Press,
2000.
Hume,
David. An Enquiry Concerning Human Understanding. Ed.
Tom L. Beauchamp.
Oxford: Oxford University Press, 1999.
Kant,
Immanuel. Critique of Pure Reason. Ed.
Paul Guyer and Allen W. Wood. Cambridge: Cambridge University Press,
2009.
1 David
Hume, A Treatise of Human Understanding, ed.
David F. Norton and Mary J. Norton (Oxford: Oxford University Press,
2000), 1.1.1.1, pg. 7.
2 David
Hume, An Enquiry Concerning Human Understanding, ed.
Tom L. Beauchamp,
(Oxford: Oxford University Press, 1999), 2.1, pg. 96.
3 Hume,
Treatise, 1.1.1.7, pg. 9.
4 Ibid.,
1.1.5.1-2, pgs.14-5.
5 Ibid.,
1.1.5.2-9, pg. 15.
6 Ibid.,
1.1.4.1-2, pgs. 12-3.
7 Ibid.,
1.1.1.9, pg. 9.
8 Hume,
Enquiry, 4.1.6, pgs. 109-10.
9 Ibid.,
4.1.1-4, pgs. 108-9.
10 Ibid.,
7.2.26, pg. 143-4.
11 I
acknowledge that the ultimate cause of the balloon floating upward
is actually the density of the gas that fills the balloon being less
than the atmosphere surrounding it. However, this is abstracted
knowledge that is well beyond simple impressions and ideas.
12 Hume,
Enquiry, 7.2.26, pg. 144.
13 Ibid.,
7.1.8-15, pgs. 136-9.
14 Hume,
Treatise, 1.3.6.10-11, pgs. 63-64.
15 Immanuel
Kant, Critique of Pure Reason, ed.
Paul Guyer and Allen W. Wood, (Cambridge, U.K.: Cambridge University
Press, 2009), B1-6, 136-8.
16 Kant,
Critique of Pure Reason, B5,
pg. 138.
17 Ibid.,
Bxxv, 114.
18 Ibid.,
B6, pg. 138.
19 Ibid.,
B6, pg. 138.
20 Ibid.,
A23/B37, pg. 157.
21 Ibid.,
A23/B37-A24/B38, pg. 157-8.
22 Ibid.,
A31/B46, pg. 162.
23 Ibid.,
A42/B59, pg. 168.
24 Ibid.,
A42/B59-A43/B60, pg. 168.
25 Ibid.,
Bxiii-Bxiv, pgs. 108-9.
26 Ibid.,
Bxv, pg. 110.
27 Ibid.,
A84/B117-A85-B118, pg. 219-20.
28 Ibid.,
A86/B118, pg. 220.
29 Ibid.,
B124, pg. 223.
30 Ibid.,
B124, pg. 223.
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