Intuition deduction thesis – Is knowledge through a priori intuition and deduction possible?
Intent: The intent of this essay is to demonstrate that knowledge can be acquired through a priori intuition and
deduction.
→ Why is it convincing? The most crucial argument Descartes is faced with is Hume’s fork which suggests that it
is impossible for synthetic a priori knowledge to exist as it does not fit in any of the two knowledge
categories; however, Descartes is able to overcome this through his wax argument which displays that
understanding of synthetic claims must come from a priori intuition i.e. reason.
1. Descartes method: suspension of judgement and eradication of doubt to defeat scepticism and achieve certain
knowledge. Starts by questioning all forms of knowledge and knowledge claims to arrive at an indubitable foundation
for knowledge. The cogito argument: only it is an a priori intuition, indubitable and a clear and distinct idea.
Criticism: Descartes never proves that thoughts exist or that “I exist”. First empiricist argument: Hume: the
self is nothing more than a bundle of sensations, emotions etc. The impact of this criticism is that if
awareness of the self is only accessible through experiences then it cannot be an a priori intuition like
Descartes claims.
Descartes' response: thoughts require a thinker. Descartes argument that mental substances exist; properties are
always properties of something. Thoughts, desires etc… are therefore properties of a mental substance. The is a
strong response as it shows how the self cannot be from sense experience as thoughts and desires are immaterial,
so they can only be accessible a priori.
Criticism: this doesn’t establish knowledge though. Descartes claims that the cogito is indubitable but this leads to
solipsism: I cannot know if minds other than my own exist. Hume objects for the purpose of the intuition deduction
thesis which aims to establish certain knowledge of the world through reason. The impact of this criticism is that
Descartes’ cogito at this stage fails to provide knowledge of the external world, meaning that it has no application
as an account of knowledge.
2. (Response) The argument from contingency: Descartes' response is his proof, through deduction that God exists:
P1: the cause of my existence as a thinking thing could be a) myself b) I have always existed or c) God.
P2: I cannot have caused myself to exist for then I would have created myself perfect. Nor can I sustain myself in
existence for then I would be God.
P3: Neither have I always existed, for then I would be aware of this.
C: Therefore, only God could have created me.
Develop on why it is a deductive argument: if the premises are true, the conclusion must be. Only logical inferences
are made so it preserves certainty. The concept of God is a clear and distinct idea. Descartes argues solipsism as God
exists.
Criticism: The cartesian circle and idea of the causal adequacy principle: Descartes assumes God into
existence in order to formulate his argument. This is a problem because by doing so his argument is not proof
for the existence of God but rather at best reaffirms the existence of God before proving the existence.
Causal adequacy is also not enough to prove that God exists, humans are able of creating ideas greater than
themselves such as superheroes. This is an issue as it shows that casual adequacy is effective at proving the
existence of God.
Response: Descartes' ontological argument: A proof that God exists solely from the definition of God as a supremely
perfect being. Link to the Descartes’ proof of the external world: the external world must exist as my sensations are
involuntary and God wouldn’t deceive me as deception is a sign of imperfection and God is a supremely perfect
being. This is a strong argument as it necessitates the existence of God, by definition God must exist.
Crucial criticism: Hume’s fork and the distinction between relations of ideas and matters of fact: The claim “God
exists” is neither a MOF nor a ROIs. Existence is not a predicate; a being cannot be defined into existence. The claim
that God exists is not a knowledge claim. A Descartes' proof that the external world exists depends of his proof that
God exists, a key premise, the argument collapses. This is a crucial criticism as it demonstrates that existence itself
tells us nothing about the nature of God, existence is assumed when discussing things meaningfully, God cannot
be discussed meaningful as he is yet to be proved.
Second crucial issue: Descartes' method: empiricists argue that the mental idea that the world exists is not a
necessity, a priori claim. It is a contingent synthetic claim, the truth of which can only be established through
experience, not reason. No claim about the world can be made on the basis of reason. This is also very crucial as it
, shows that if knowledge is solely a priori as Descartes claims, then knowledge of the external world would be
impossible, experience tells us there is an external world.
3. Descartes' response: wax analogy argument: experience cannot tell us that the wax remains the same despite
complete physical change. Only the concept of physical substance (and what it entails that physical substances can
remain the same despite complete change of properties) is something we know through intuition (clear and distinct
idea). Additional argument: Link this with Leibniz’ argument for necessary truths, whilst access to the external world
may be synthetic, it is impossible to understand fundamental laws of the world/universe without a priori intuition.
This is the strongest and most convincing argument as it removes the false dichotomy between a priori and a
posteriori knowledge – both are necessary for having knowledge of an external world.
Conclusion: In conclusion Descartes’ argument that knowledge through a priori intuition and deduction can
successfully be defended. Descartes’ wax argument and Leibniz’ argument for necessary truths demonstrates that
empiricist claims that knowledge can only be a posteriori is false, without a priori intuition it is impossible to
understand the truth nature of the world e.g. seasonal changes, causation etc.
Intent: The intent of this essay is to demonstrate that knowledge can be acquired through a priori intuition and
deduction.
→ Why is it convincing? The most crucial argument Descartes is faced with is Hume’s fork which suggests that it
is impossible for synthetic a priori knowledge to exist as it does not fit in any of the two knowledge
categories; however, Descartes is able to overcome this through his wax argument which displays that
understanding of synthetic claims must come from a priori intuition i.e. reason.
1. Descartes method: suspension of judgement and eradication of doubt to defeat scepticism and achieve certain
knowledge. Starts by questioning all forms of knowledge and knowledge claims to arrive at an indubitable foundation
for knowledge. The cogito argument: only it is an a priori intuition, indubitable and a clear and distinct idea.
Criticism: Descartes never proves that thoughts exist or that “I exist”. First empiricist argument: Hume: the
self is nothing more than a bundle of sensations, emotions etc. The impact of this criticism is that if
awareness of the self is only accessible through experiences then it cannot be an a priori intuition like
Descartes claims.
Descartes' response: thoughts require a thinker. Descartes argument that mental substances exist; properties are
always properties of something. Thoughts, desires etc… are therefore properties of a mental substance. The is a
strong response as it shows how the self cannot be from sense experience as thoughts and desires are immaterial,
so they can only be accessible a priori.
Criticism: this doesn’t establish knowledge though. Descartes claims that the cogito is indubitable but this leads to
solipsism: I cannot know if minds other than my own exist. Hume objects for the purpose of the intuition deduction
thesis which aims to establish certain knowledge of the world through reason. The impact of this criticism is that
Descartes’ cogito at this stage fails to provide knowledge of the external world, meaning that it has no application
as an account of knowledge.
2. (Response) The argument from contingency: Descartes' response is his proof, through deduction that God exists:
P1: the cause of my existence as a thinking thing could be a) myself b) I have always existed or c) God.
P2: I cannot have caused myself to exist for then I would have created myself perfect. Nor can I sustain myself in
existence for then I would be God.
P3: Neither have I always existed, for then I would be aware of this.
C: Therefore, only God could have created me.
Develop on why it is a deductive argument: if the premises are true, the conclusion must be. Only logical inferences
are made so it preserves certainty. The concept of God is a clear and distinct idea. Descartes argues solipsism as God
exists.
Criticism: The cartesian circle and idea of the causal adequacy principle: Descartes assumes God into
existence in order to formulate his argument. This is a problem because by doing so his argument is not proof
for the existence of God but rather at best reaffirms the existence of God before proving the existence.
Causal adequacy is also not enough to prove that God exists, humans are able of creating ideas greater than
themselves such as superheroes. This is an issue as it shows that casual adequacy is effective at proving the
existence of God.
Response: Descartes' ontological argument: A proof that God exists solely from the definition of God as a supremely
perfect being. Link to the Descartes’ proof of the external world: the external world must exist as my sensations are
involuntary and God wouldn’t deceive me as deception is a sign of imperfection and God is a supremely perfect
being. This is a strong argument as it necessitates the existence of God, by definition God must exist.
Crucial criticism: Hume’s fork and the distinction between relations of ideas and matters of fact: The claim “God
exists” is neither a MOF nor a ROIs. Existence is not a predicate; a being cannot be defined into existence. The claim
that God exists is not a knowledge claim. A Descartes' proof that the external world exists depends of his proof that
God exists, a key premise, the argument collapses. This is a crucial criticism as it demonstrates that existence itself
tells us nothing about the nature of God, existence is assumed when discussing things meaningfully, God cannot
be discussed meaningful as he is yet to be proved.
Second crucial issue: Descartes' method: empiricists argue that the mental idea that the world exists is not a
necessity, a priori claim. It is a contingent synthetic claim, the truth of which can only be established through
experience, not reason. No claim about the world can be made on the basis of reason. This is also very crucial as it
, shows that if knowledge is solely a priori as Descartes claims, then knowledge of the external world would be
impossible, experience tells us there is an external world.
3. Descartes' response: wax analogy argument: experience cannot tell us that the wax remains the same despite
complete physical change. Only the concept of physical substance (and what it entails that physical substances can
remain the same despite complete change of properties) is something we know through intuition (clear and distinct
idea). Additional argument: Link this with Leibniz’ argument for necessary truths, whilst access to the external world
may be synthetic, it is impossible to understand fundamental laws of the world/universe without a priori intuition.
This is the strongest and most convincing argument as it removes the false dichotomy between a priori and a
posteriori knowledge – both are necessary for having knowledge of an external world.
Conclusion: In conclusion Descartes’ argument that knowledge through a priori intuition and deduction can
successfully be defended. Descartes’ wax argument and Leibniz’ argument for necessary truths demonstrates that
empiricist claims that knowledge can only be a posteriori is false, without a priori intuition it is impossible to
understand the truth nature of the world e.g. seasonal changes, causation etc.
