Kant – Science vs. Religion in Modern Philosophical Thought (Metaphysics & Epistemology)

Metaphysics: Initial Questions

• Kant’s opening concern: “Is metaphysics possible?”
  • Two horns of the dilemma:
  • Yes → Why has it failed to achieve the recognized progress and unanimity of the natural sciences?
  • No → Why does it persist in the pretence of being a science at all?
• Core difficulty: there is no agreed-upon measure in metaphysics to separate sound knowledge from mere talk.
• By asking the question of possibility, Kant openly allows for the suspicion that metaphysics may be impossible.

Metaphysics and the Humean Challenge

• Kant’s famous confession (p. 678):
  • Quote: “I openly confess, the suggestion of David Hume was the very thing … that first interrupted my dogmatic slumber.”
• Hume argued that necessary connections cannot be discovered a priori.
  • If Hume is right, all a-priori metaphysical links collapse, destroying traditional metaphysics.
• Kant takes Hume’s challenge as the impetus to build a “sturdy foundation” for metaphysics that rescues necessity without appeal to empiricism.

Source of Metaphysical Knowledge

• By definition, metaphysics cannot be empirical; its knowledge must be a priori.
  • Class reminder:
  • A priori = independent of experience.
  • A posteriori = dependent on experience.

Analytic vs. Synthetic Judgments

• Analytic judgment: predicate is contained in the concept of the subject.
  • Example: “All bachelors are unmarried men.”
  • Necessarily a priori because merely unpacking a concept yields truth.
• Synthetic judgment: predicate adds something new to the subject.
  • Example: “All swans are white.”
  • Can be either a priori or a posteriori.
  • Empirical science = synthetic a posteriori.
  • Mathematics & metaphysics = synthetic a priori.

Synthetic A Priori Judgments

1. Mathematics

• Every mathematical truth (e.g. (7+5=12)) is synthetic a priori:
  • We must go beyond the concepts “7,” “5” to grasp their union (synthetic).
  • The result “12” is grasped with necessity (a priori).
• Historically mistaken for analytic simply because of their necessity.

2. Metaphysics

• Also aims at synthetic a priori propositions.
  • Distinction:
  • Judgments pertaining to metaphysics: agreed-upon analytic definitions.
  • Metaphysical judgments proper: synthetic statements built upon those definitions.
• Crisis: Metaphysicians disagree about which synthetic judgments truly belong, hence no cumulative progress.

Kant’s Method: From Math & Physics to Metaphysics

• Fact-check: synthetic a priori judgments undeniably work in mathematics and physics.
• Strategy: Analyze how they are possible in those domains → extract the principles → apply to metaphysics.

Pure Mathematics: Conditions of Possibility

• Mathematical cognition = connecting concepts via pure intuitions.
• Therefore, determine what pure intuition is.

Intuition: Empirical vs. Pure

• Empirical intuition: sense perception linking one sensation to another.
• Pure intuition: concept-connections without sense input.
  • Puzzle: How can the mind possess such non-empirical structures?

Space & Time as Pure Intuitions

• We can anticipate objects prior to experience only if the intuition contains nothing except the form of sensibility.
• Result: Space (outer sense) & Time (inner sense) are pure intuitions that shape every possible experience.
• Terminological pair:
  • Phenomena = objects as they appear within space-time → only level humans can know.
  • Noumena = “things-in-themselves,” objects independent of our mode of representation → unknowable.
• Geometry = study of pure intuition of space.
• Arithmetic/ pure mechanics = rely on pure intuition of time (e.g. motion).
• Therefore mathematics has objective reality when applied to phenomena because it merely sets the rules of the space-time stage.

Pure Natural Science (Physics): Conditions of Possibility

• Nature concerns objects of experience, not things in themselves.
• Two tiers of natural science:
  1. Empirical (a posteriori): facts like inertia, impenetrability.
  2. Pure (a priori): laws that make experience possible and govern appearances (e.g. “substance is permanent,” “every event has a cause”).
• Experience emerges only when pure concepts of understanding are brought to empirical intuitions.
• Kant’s synthesis:
  \text{Senses (intuition)} + \text{Understanding (concept)} \Rightarrow \text{Experience}
• Because a transcendental system of pure concepts undergirds necessary judgments, pure natural science is possible.

Judgments of Perception vs. Judgments of Experience

• Judgments of Perception
  • Merely link sensations via logic; subjective validity only.
  • Do not yet qualify as experiences.
• Judgments of Experience
  • Attain objective validity & necessity.
  • Require application of pure concepts of understanding (categories).
  • Become part of the shared, public domain of knowledge.

Logical Table of Judgments

• Kant parses every judgment into four headings—Quantity, Quality, Relation, Modality—each with three sub-types.
  • Example “All men are mortal” = Universal / Affirmative / Hypothetical / Assertoric.
• This logical analysis grounds the discovery of the transcendental categories.

Transcendental Table of Pure Concepts of Understanding (Categories)

• Each logical function corresponds to an a-priori concept enabling objective experience:
  • Quantity → Unity, Plurality, Totality
  • Quality → Reality, Negation, Limitation
  • Relation → Substance, Cause, Community
  • Modality → Possibility, Existence, Necessity
• These categories transform subjective perceptions into objective experiences.

Pure Physiological Principles of Natural Science

• Four subclasses: Axioms of intuition, Anticipations of perception, Analogies of experience, Postulates of empirical thinking.
• They state the universal, necessary laws to which any natural science must conform.

Metaphysics in General: Possibility & Limits

• Mathematics works via space & time; Physics works via categories.
• Metaphysical objects, however, lie beyond possible experience; no intuition or category can supply them with objective reality.
• Pure reason nonetheless demands unity and pushes thought toward the unconditioned → spawning classical metaphysical topics (soul, world totality, God).
• Danger: we project ideas (regulative ideals) as if they were objects (constitutive realities) → illusions.
• Remedy: Reason must perform a critique of itself to mark proper boundaries.

Ideas of Pure Reason

1. Psychological Idea (Soul)

• “Substance” here is only an idea; the “I” is a representation/feeling that accompanies thoughts.
• We cannot legitimately infer a permanent, immortal soul because permanence cannot be given in inner sense.

2. Cosmological Idea (World-Whole)

• Concerned with sensible objects yet asks for unconditional totality; yields antinomies—pairs of equally rational yet contradictory propositions:
  1. World has a beginning vs. World is infinite.
  2. Everything composed of simples vs. No simples, only composites.
  3. Freedom causes events vs. All events are natural necessity.
  4. Necessary Being exists in the series vs. All is contingent.
• Root error: treating space & time (mere forms of representation) or part-whole relations as things-in-themselves.

3. Theological Idea (God)

• Idea of a most perfect primal Being that grounds possibility and actuality.
• Illusion arises from assuming the subjective conditions of thinking are also the objective conditions of being.

Untying the Knots: Science of Metaphysics

• Metaphysics is subjectively unavoidable—reason naturally asks such questions.
• To achieve scientific status we must:
  • Separate Categories (understanding) from Ideas (reason).
  • Clarify and respect the boundaries of each faculty.

Final Picture: Kant’s Three Faculties

• Sensibility: supplies pure intuitions (space & time) → makes raw data coherent.
• Understanding: supplies categories → renders data lawful (nature).
• Reason: supplies ideas → seeks unconditioned totality but must remain regulative.
• Key lesson: Noumenal reality is inaccessible; knowledge is limited to phenomena.

Practical, Ethical & Real-World Implications

• Science vs. Religion: Kant allows science full reign over phenomena, while assigning religion and morality to the domain of reason’s practical use (not covered fully here but implied by the boundary-drawing).
• Humility of knowledge: Recognizing limits curbs dogmatism and fanaticism in both science and theology.
• Moral autonomy (developed in later works): Once theoretical reason is limited, practical reason gains room to assert freedom, duty, and God as postulates of moral life.

Formula & Numerical References

• Prototype synthetic a priori formula: (7+5=12).
• Formal synthesis of experience: \text{Intuition}+\text{Category}=\text{Experience} (conceptual, not numerical).

Study Tips & Connections

• Relate Kant’s categories to earlier Aristotelian logic (Quantity, Quality, Relation, Modality).
• Contrast Hume’s empiricism (constant conjunction) with Kant’s necessary synthetic a priori.
• Observe Kant’s influence on modern debates over scientific realism, phenomenology, and analytic/continental divides.
• For ethics class: remember that delimiting theoretical reason opens the door to the primacy of the practical.

Bottom Line: Kant rescues necessity (mathematics & physics) by rooting it in the mind’s own structures—but, in doing so, he also shows why metaphysics can only be a critique of reason rather than a discovery of things-in-themselves.