Download Or is some synthetic knowledge innate?

SYNTHETIC KNOWLEDGE
Note: Before reading this handout, you must have read and fully
understood the sheet of key terms.
Remember: by “knowledge”, we mean claims or propositions such as
“Paris is the capital of France”, “it is raining outside” or “all triangles have
three sides”.
Make sure you are clear about the difference between knowledge like
this and concepts (like “France”, “rain” or “triangles”).
KNOWLEDGE EMPIRICISM
The claim that all synthetic knowledge is a posteriori and all a priori
knowledge is (merely) analytical.
Hume’s Fork
Hume’s Fork is the name given to a distinction Hume
draws between different kinds of knowledge.
“All the objects of human reason or enquiry fall naturally
into two kinds, namely relations of ideas and matters of
fact.”
By this, Hume means that there are two types of
knowledge. All knowledge is either a “relation of ideas” or a
“matter of fact”. He claims that any proposition which is
neither of these is meaningless.
Matters of Fact are facts about the world and we gain this
kind of knowledge through our sense experience. This
sense experience might be direct (I look out the window to
know that it is raining) or indirect (I read in a book that the
battle of Hastings happened in 1066).
Relations of Ideas are the kinds of knowledge claims we
use in maths (2+3=5) or in logic (something cannot exist
and not exist at the same time). We do not gain this
knowledge through sense experience, but through reason
(just thinking about the concepts involved).
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The main differences between these two kinds of knowledge are
outlined below:
Covers
Examples
Certainty Level
How we know
Reliance on how the
world is
Is the opposite
conceivable?
Relations of Ideas
Mathematics,
geometry, logic
2 + 4 =6.
All triangles have
three sides.
Absolute
By thinking alone
(called a priori)
None. Would be true
in all possible worlds.
(called necessarily
true)
No. It is true by
definition (called an
analytic truth)
Matters of Fact
Facts, generalisations
about the world
Barack Obama was a
US president.
Water can turn into
ice.
Less than 100%
By experience (called
a posteriori)
Complete reliance on
how the world is. If the
world were different, it
wouldn’t be true
(called contingently
true)
Yes, the opposite is
conceivable and
possible (called a
contingent truth)
So, Hume is claiming that all synthetic knowledge is a posteriori. This
means that we get knowledge about the world by experiencing the
world. He is also claiming that all a priori knowledge is analytic. This
means that there is some knowledge that we acquire without any sense
experience, based on the terms involved. But it doesn’t tell us anything
new about the world.
This view is known as knowledge empiricism.
Opponents of empiricism claim that there is some a priori knowledge
which is synthetic. This means that there is new knowledge about the
world that we can gain without the need for any sense experience. Since
it isn’t gained by sense experience, it either must be gained through
reason (rationalism) or it is innate (knowledge innatism).
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KNOWLEDGE INNATISM
There is at least some innate a priori knowledge
Knowledge innatists claim that we can have synthetic a priori knowledge
about the world. This means we can have knowledge gained by reason,
not by the senses, which is substantial and not just true by definition.
Plato – Mathematical knowledge is innate
Plato argues that learning is just
remembering things that we
already have knowledge of, we
just don’t realise it.
He uses the example of
mathematical or geometrical
knowledge. Socrates asks
Meno’s slave boy (who has
never been taught geometry) a
series of questions, leading him
to figure out a geometrical
theorem.
Since the boy’s knowledge did
not come from experience, it
must have been innate. And
since it is not true simply by definition, it must also be synthetic.
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Another example from geometry is the work of another ancient GreekEuclid. Euclid was a mathematician who established the foundations of
geometry. It was a set of basic principles which were held to be selfevident and which couldn’t be doubted.
Examples of Euclid’s principles include:
Parallel lines never meet each other.
Every point on a circle is the same distance
from the centre.
Because these propositions seem so obviously true, and
everyone would agree with them, it can be argued that these are
examples of innate, a priori knowledge. Since once again some would
argue that we cannot establish these proposition simply by looking at the
definitions, these statements would also be considered synthetic,
Leibniz – All a priori truths are necessary and innate
Leibniz argued that there can be innate synthetic knowledge that we
have, but are unaware of.
An example is the claim
“It is impossible for the same thing to both be and not be”.
This is knowledge not true by definition (synthetic) that we can know just
through thinking (a priori). Everyone uses this knowledge all the time
(when it comes to identifying the differences between things in the
world), but without really being aware of it:
“Even if we give no thought to them, they are necessary for thought. The
mind relies on these principles constantly.”
In fact, Leibniz goes as far as arguing that all a priori knowledge is
innate.
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Because we can work it out just by using our mind, it must have been
there in our minds all along. That is, it must be innate.
Leibniz argues that we come to know these innate truths by “attending to
what is already in our minds”, and he cites Plato’s Meno as an example
of this.
KNOWLEDGE EMPIRICIST ARGUMENTS
AGAINST KNOWLEDGE INNATISM
To prove the innatist wrong, the empiricist needs to explain how these
examples of synthetic knowledge could have come about if they are not
innate.
“Innate knowledge” is not really knowledge
One way to do this is to argue that it is not really knowledge.
For example, although Euclid’s principles of geometry seem to be true in
all cases, the work of Einstein and others now suggests that this is not
the case. The real world may not be Euclidean, so in reality, parallel
lines do meet, just not in a way that can be observed by the human eye.
If Euclid’s principles are not actually true, then they are not
knowledge (given the usual definition). So they are not an example
of innate synthetic knowledge.
Parallel lines in non-Euclidean space:
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“Innate knowledge” is actually a posteriori
The empiricist could respond to suggestions of innate knowledge by
claiming that these examples are gained not by reason, but by sense
experience.
For instance, the slave boy was basing his knowledge on his experience
of squares. And Euclid knew that parallel lines don’t meet because of his
experience of parallel lines.
Some philosophers, such as Mill, have argued that all mathematical
knowledge is actually based on experience. For instance, I know that 2 +
3 = 5 because I have seen 2 things and 3 things, and when I put them
together I have seen that they make 5.
Mill claims that there is no a priori knowledge. All knowledge is a
posteriori.
If sense experience is required to know these propositions, then
they are not innate or a priori.
“Innate knowledge” is actually analytic
Another way the empiricist can respond is to claim that these proposed
“innate” propositions are only analytically true. They are true just
because of the meanings of the words, so they tell us nothing new about
the world.
For instance, it is part of the definition of parallel lines that they don’t
meet. Similarly, if you know the definition of the word “circle”, then you
automatically know that all the points are the same distance from the
centre. This claim isn’t separate from the definition itself.
For Leibniz’s example of “the same thing can’t both be and not be”,
again if you understand all the words in this sentence, then you know
that the claim is true. This truth isn’t something separate from the
definitions in the sentence.
If these truths are not synthetic but analytic, then the innatist has
failed to prove that there is innate synthetic knowledge.
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Locke’s arguments against innatism
Locke gave several arguments against the idea of innate knowledge in
general, using common examples such as “It is impossible for the same
thing both to be and to not be”.
1. His first point is the same one he made about innate concepts - No
proposition is known universally (“children and idiots” do not
understand them, so they can’t know them). If it isn’t universal,
then it isn’t innate.
The innatist can respond by claiming that innate knowledge doesn’t
require that everyone actually knows it, but that everyone would know
it they used their reason correctly to work it out.
Locke responds by asking, if it really is innate, so we already have it,
then why do we need reason to discover it?
2. The innatist might claim that innate knowledge is “self-evident”.
That is, we agree that it is true as soon as we think of it. But Locke
thinks this seems to be the case for lots of knowledge that is not
innate. For example, “white is not black” is self-evident. But our
knowledge of it seems a posteriori (based on sense experience).
Just being self-evident does not automatically make something
innate.
3. Locke’s final argument against the innatist is that for innate
knowledge to be possible, the concepts it is based on must be
innate. If they are not innate it means any knowledge built on them
has its roots in our experience, meaning we’d surely say it’s a
posteriori. Since he believes he has proved innate concepts to be
impossible (see previous handout), innate knowledge cannot be
possible.
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Reliance on the non-natural
One final problem for the innatist is, if knowledge doesn’t come from
sense experience, where does it come from?
Plato’s answer is that the non-physical mind existed, containing this
knowledge, before birth. Leibniz and Descartes argue that innate
knowledge must come from God.
If we don’t accept these non-natural explanations, then it doesn’t seem
like we can accept the existence of innate knowledge.
Some modern philosophers have appealed to natural explanations, such
as evolution, as an explanation. While this appears to work for certain
knowledge claims, such as “physical objects exist” or “beings with other
minds exist”, it is difficult to see how we could evolve to have knowledge
of geometry or maths.
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RATIONALISM
We can gain synthetic a priori knowledge through intuition and deduction
Like knowledge innatists, rationalists claim that we can have real new
knowledge about the world that is not based on sense experience
(synthetic, a priori knowledge). But rather than it being present in
everyone at or before birth, we can come to know it by using our powers
of reason.
Intuition and Deduction Thesis
Rational intuition means the ability to understand something just by
thinking about it.
Deduction means figuring out what must follow from certain claims. So,
once you accept one claim as being true, deduction is the ability to move
from that to other true claims, just by thinking about them.
Intuition and Deduction Thesis is the theory that we can gain substantial
knowledge by using our rational intuition and/or deduction (that is, we
can gain knowledge just by thinking).
Philosophers who accept the intuition and deduction thesis are known as
rationalists.
The main rationalist philosopher is Descartes, and we’ll now look at his
main ideas in detail:
Important Note: Whilst we will attempt to apply the definitions we’ve used
throughout this topic to Descartes work, it’s worth noting he was writing
before distinctions such as A Priori, A Posteriori, Analytic and Synthetic had
been outlined philosophically. Thus there is some debate about where his
ideas actually fall. Regardless, he certainly believed there were things he could
know about the world just by thinking.
Descartes’ doubt
In the Meditations Descartes places all his previous knowledge in doubt
in order to find a secure foundation which can’t be doubted. Descartes’
doubt comes in three waves.
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First, the reliability of the senses as a source of knowledge is rejected
because of illusions and hallucinations. Then he employs the argument
from dreaming to suggest that even his ability to tell the difference
between reality and illusion could be compromised (because we could
be dreaming and we wouldn’t know). Finally he imagines that an evil
demon is deceiving him about everything, even about mathematical
truths. Since all these things could be affecting him, everything he thinks
he knows is in doubt.
A priori knowledge of the self
Having pushed this method of doubt to its ultimate
limits, Descartes now sees that there is at least one
truth which cannot be doubted. He reasoned that if he
was doubting everything, he could be sure of one thing:
that he existed. For, if he was doubting, he must exist
in order to doubt. Going further, doubting is a form of
thinking, so he must exist in order to think.
“Cogito ergo sum”; I think, therefore I am.
He now has certain, undoubtable knowledge of
his own existence. This knowledge is not
derived from any kind of sense experience, but
on his own reason and deduction.
“If there is a deceiving demon then ‘I too undoubtedly exist, if he is
deceiving me. Let him deceive me as much as he can, he will never
bring it about that I am nothing, so long as I think I am something.’
Hence, ‘I am, I exist’ is necessarily true whenever it is put forward by me
or conceived in my mind.”
Having established his existence, Descartes now proceeds to
investigate his nature or essence – what type of thing is he? He is not
essentially a physical being, for, applying the method of doubt, he can
doubt his own body – or indeed whether any external objects exist. The
only attributes which he cannot deny of himself are mental ones, and
hence he concludes that:
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‘I am a substance whose whole nature or essence is to think and whose
being requires no place and depends on no material thing’.
Clear and Distinct Ideas
From this one item of certain knowledge (i.e. the cogito), he derives a
criterion of certainty- what Descartes calls clear and distinct ideas:
Knowledge of oneself is clear and distinct, self-evident. Generalising
from this, Descartes concludes that whatever is clear and distinct is true
and cannot be doubted: it is knowledge.
These clear and distinct ideas have nothing to do with the perceptions of
the senses; instead they are purely intellectual like the basic, selfevident propositions of mathematics and logic.
A priori knowledge of God
He thinks that the existence of God is a clear and distinct idea, or is
deduced from ideas that are clear and distinct. He gives a number of
arguments supporting this claim, but the most common is his ‘trademark
argument’. While he is aware of his own imperfections, he is also aware
that he has within himself the idea of a supremely perfect being.
Descartes reasons that this idea must have been placed in him by a
really existing perfect being – God (see the trademark argument in
handout E5).
So when the question arises, “How do you know that a demon is not
deceiving you into thinking that whatever is clear and distinct is always
true?,” from now on Descartes can answer that God, being good and all
powerful, would not allow him to be so deceived.
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From God to the World
But do bodies – do physical objects – exist? Of course, we might say:
they cause our experiences. But Descartes has argued that we don’t yet
know what causes our experiences – it could be a demon or
supercomputer. Descartes later argues that there are only three options
for what might cause these experiences: a real external world of physical
objects, a demon, or God.
1. If the cause was God, this would mean that God was a deceiver
because He would have created us with a very strong tendency to
believe something false (viz. that a physical world exists).
2. if it was a demon, then if God exists, God is as good as a deceiver,
since God is allowing the demon to deceive us.
However, Descartes argues, God is perfect by definition. Because we
know that God is perfect, we know that God is not a deceiver. So if God
exists (see arguments above), then there must really be an external
world.
A priori knowledge of the external world
Finally when it comes what we know of the world, Descartes decides to
apply his new method of ignoring the senses and relying on a priori,
clear and distinct ideas. He gives the example of a piece of wax:
‘Let us take, for example, this piece of wax. It
has just been taken from the honeycomb; it
has not yet quite lost the taste of the honey; it
retains some of the scent of the flowers from
which it was gathered; its colour, shape and
size are plain to see; it is hard, cold and can
be handled without difficulty; if you rap it with
your knuckle it emits a sound … But even as I
speak, I put the wax by the fire and look: the
residual taste is eliminated, the smell goes
away, the colour changes, the shape is lost,
the size increases; it becomes liquid and hot,
and if you strike it it no longer emits a
sound…
… So what was it in the wax which I understood with such
distinctness? Evidently none of the properties arrived at by means
of the senses’.
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So, the perceivable properties of the wax give us no real knowledge
about the wax itself. The only essential property of the wax is its
extension: it is simply an extended thing which has length, breadth and
depth (although these dimensions can change). But this is not
something we perceive via the senses or the imagination, for we know
the wax is capable of taking on many more shapes than we can ever
actually observe or picture to ourselves.
Descartes’ argument here goes like this:
1. My sense experience of the wax changes. Nothing I can sense
is the same.
2. I know it is the same piece of wax.
3. Therefore, my knowledge of the wax is not based on my sense
experience, but on deduction.
So Descartes concludes that ‘we know that bodies are not strictly
perceived by the senses or by the faculty of imagination but by the
intellect alone’.
So, Descartes has used pure reason (intuition and deduction) to
come to know three propositions: that he exists, that God exists
and that the external world exists in an extended form.
He has gained this knowledge without any use of his senses, so it is a
priori. But it does tell him meaningful new information about the world, so
it is synthetic.
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KNOWLEDGE EMPIRICIST ARGUMENTS
AGAINST INTUITION AND DEDUCTION
There are two main criticisms of Descartes’ rationalism:
 The first is that his conclusions do not really follow from his
reasoning.
 The second is that even if his conclusions did follow, they are not
meaningful.
The ‘Cartesian circle’
A major problem with Descartes’ argument is that it relies on circular
reasoning:
We cannot trust our clear and distinct perceptions until we know that
God exists; but we cannot prove God exists without relying on our clear
and distinct perceptions.
Descartes’ answer to this notorious problem (known as the ‘Cartesian
circle’) appears to be that there are some propositions which are so
clear and distinct that, even without relying on God, they are selfguaranteeing. ‘Two plus two equals four’ or ‘if I think, I exist’ are such
simple and straightforward propositions that I cannot possibly be
mistaken as to their truth.
Tautology (analytic truths)
The difficulty for Descartes, however, is that such tautologous or neartautologous propositions give us very little information. The knowledge
he can establish without relying on circular reasoning is merely analytic:
it merely tells us the meaning of the words within the proposition.
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But as soon as we want to go further, to establish more substantial
claims about the existence of God or the nature of the universe, then it
seems that we are moving beyond these self-evident truths. Since they
are not self-evident and we can’t rely on circular reasoning, we can’t
really know that they are true.
So, Descartes seems to face a fatal dilemma. Either his knowledge
begins and ends with thin and unexciting propositions such as ‘two plus
two equals four’ or ‘if I am thinking, I exist’, which buy their truth at the
cost of being relatively uninformative; or else it advances to more
important and substantive truths at the cost of losing the kind of certainty
and necessity which he was originally looking for.
ARGUMENTS AGAINST KNOWLEDGE
EMPIRICISM
The limits of empirical knowledge
However much we may doubt Descartes’ rationalist argument for a priori
synthetic knowledge, his sceptical argument about the reliability of the
senses raises important issues with knowledge empiricism. If our senses
can be easily deceived (by illusions, hallucinations etc.) then how can
they give us accurate knowledge of the world? But much of what we
consider to be knowledge does not derive from the senses.
Empiricists deny that there is any a priori knowledge of synthetic
propositions. It follows from this that any claim that is neither analytic nor
known a posteriori, we do not know. However this rules out many claims
that we like think we do know. For instance it appears to show that we
cannot know that physical objects exist – which few people would agree
with. If we don’t want to rule out this type of knowledge, then we must
admit that empiricism is false. Consider:
1. (According to empiricism) All knowledge of synthetic
propositions is a posteriori
2. ‘Physical objects exist’ is a synthetic proposition
3. But we cannot know, through senses experience, that physical
objects exist.
4. Therefore, (according to empiricism) we cannot know that
physical objects exist.
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5. Therefore, either we cannot know that physical objects exist, or
empiricism is false.
6. But we can know that physical objects exist
7. Therefore empiricism is false.
Morality
Moreover, this argument can be adapted to generate objections to
empiricism in other areas of knowledge, for example morality. Moral
claims, such as ‘murder is wrong’, don’t appear to be analytic. But could
we know them through sense experience? Which of our senses pick up
on ‘wrongness’, and how? If empiricists can’t show that moral claims are
either analytic or a posteriori, then they will be forced to conclude that
there is no moral knowledge.
Science
Another problem area for empiricists is science. Scientific knowledge is
based on the assumption that because certain events have always
happened in the same way in the past, they will in the future. Our sense
experience can give us knowledge that a chemical behaved in a certain
way yesterday, and the day before, and when a colleague did the same
experiment 2 years ago. Although it is highly probable that it will happen
this way on future occasions, it is not guaranteed. This is known as the
problem of induction. Inductive reasoning is the basis for scientific
knowledge, and yet it doesn’t come from the senses. So either it is not
knowledge, according to empiricism, or empiricism is false.
Relying on sense experience
If knowledge empiricism is to work, it needs to be based on a reliable
theory of perception. We have already seen that the debate about
perception is far from over. So, it seems that our senses cannot give us
certain knowledge of anything.
Final Thoughts…
Is all synthetic knowledge a posteriori?
Or is some synthetic knowledge innate?
Or can we gain synthetic knowledge through reason?
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