Philosophy 2

Realism, Idealism, Materialism, Rationalism, Empiricism

  • Idealism: only ideas are real.
  • Materialism: only matter is real.
  • Some argue matter is epiphenomenal on material, or that matter is nothing apart from ideas in particle physics.
  • Rationalism: knowledge of reality resides in the mind alone.
  • Empiricism: knowledge of reality comes from the senses; arguably associated with Aristotle as a leading empiricist in the traditional sense.
  • Realism (philosophical sense in this course): to say something is real means it exists outside the mind; real things exist independently of one’s thoughts.
  • Example: Annie is real because Annie exists outside one’s mind; you can prove this by recognizing that insulting oneself is not a reliable test of existence (humorous aside).
  • Realism vs nominalism:
    • Realism can also mean that universals are real (e.g., red exists; the chair as a universal chairness exists, not merely as a named collection of particular chairs).
    • Nominalism: universals such as red, redness, chairness, or justice do not exist outside the mind; they are just words we invent. There are red things, but there is no abstract property called red that exists independently.

Major philosophical positions and figures

  • Monism: only ideas or only matter are real (not both).
    • Example monists: Leibniz, Plato (in certain readings): ideas are all that’s real.
  • Dualism (Descartes): mind and matter are both real but belong to different realms; not reducible to one another.
  • Aristotle is often associated with empiricism and natural philosophy; he is typically not labeled a pure empiricist in the modern sense but is aligned with the empiricist tradition in science based on observation.

Realism, dogma, and skepticism

  • Dogma (basic definition): a belief someone holds to be true, often taught by authority.
  • Skepticism (Sextus Empiricus and skeptical tradition): rejection of dogmatism in philosophy; two main skeptical strands discussed:
    • Academic skeptics (the Academics): claim truth is possible but say we cannot know it; they argue that knowledge of truth is impossible to attain.
    • Pyrrhonists (Pyrrho and Pyrrhonists): claim we don’t know whether truth can be known; they seek to suspend judgment and maintain a state of inquiry without asserting knowledge.
  • Three types of philosophers (as per Sextus Empiricus’ typology):
    • Dogmatists (dogmatics): claim to know the truth.
    • Academics: hold that truth is possible, but achieving certain knowledge is unlikely or impossible; claim that knowledge might be possible while acknowledging difficulties.
    • Pyrrhonists (the Purists in the transcript): believe that world knowledge is uncertain; they seek truth but insist that we cannot claim certainty; they pursue arguments to show the failure of proof without committing to belief in any side.
  • The difference between skeptics and Pyrrhonists: both reject dogma, but academics believe truth is possible (even if not attainable with certainty), while Pyrrhonists refrain from concluding anything about truth’s attainability and emphasize ongoing inquiry.
  • Skepticism targets common dogmas of major schools (Skeptics criticize Pythagoras, Plato (variously), Aristotle, Epicurus, and the Stoics).
  • Cynics were a separate school often associated with public behavior that was seen as vulgar or dog-like; not the main focus of this lecture.
  • Plato’s status: Plato can be read as both dogmatic and skeptical depending on era and interpretation; emphasis on how demonstration and certainty are treated in different contexts.

Plato, forms, and the two-world view

  • Plato’s two-world model:
    • World of Forms (the realm of permanence and reality): beauty, truth, justice, numbers, and other perfect, unchanging ideas exist here.
    • World of appearances (the realm of becoming or entities/beings): changing, transient, perceptible objects; what we perceive is a copy or shadow of true Forms.
  • Key analogy: a true boyfriend/girlfriend is the “real” form of love; individual relationships are changing but participate in or imitate the Form of Love.
  • The Forms are true; the changing copies in the sensible world are not, because they are in flux.
  • The two-world theory is a central feature of Platonism and later Neo-Platonism, influencing much of later medieval and Renaissance thought.

Presocratics, physics, and the natural philosophers

  • The Presocratics were often called the physicists (natural philosophers) because they sought to explain nature (phusis in Greek) and the principles underlying the natural world.
  • Pythagoras (and the Pythagoreans) had a profound influence on Plato and later neoplatonism; much of what we know about Pythagoras comes from later writers (hagiography) rather than his own writings. The term hagiography refers to writings that present someone in an overly reverent or saint-like manner; it complicates how we reconstruct his ideas.

Pythagoras and the Pythagoreans

  • Life and sources:
    • Pythagoras is thought to have been born on the island of Samos around circa year ~May (circa = approximately).
    • He later moved to Croton (Crotone) in Italy ~30 years later, where he became politically influential; he then moved to Metapontum after clashing with Croton citizens.
    • He led an all-male community; members were vegetarians due to beliefs in reincarnation; he forbade eating beans.
    • He wrote nothing himself; our knowledge of his ideas comes from others; his school lasted about a thousand years.
    • Because of sparse and possibly mythologized sources, it is better to talk about the Pythagoreans rather than Pythagoras as an individual.
  • Core ideas:
    • Nature is number (numerical). Reality is made up of ideas or numbers; the world is interpretable through mathematics.
    • Pythagoras is considered an idealist: reality is ultimately mental/formal in nature.
    • He is a major influence on Plato and on later neoplatonism; his ideas are foundational for the later mathematical turn in philosophy.
  • Metempsychosis (transmigration of souls):
    • Metempsychosis (also called transmigration of souls) is the belief that souls migrate from one body to another after death.
    • Pythagoras is associated with the doctrine of reincarnation (metempsychosis).
    • Terms: metamorphosis; eternal recurrence (a related but distinct concept) is attributed to Pythagoras and later to Empedocles and Nietzsche.
  • Eternal recurrence:
    • The idea that everything repeats in cycles indefinitely; all events recur an infinite number of times.
    • Empedocles attributed cycles on a long timescale (e.g., ten thousand year cycles); Nietzsche later popularized the notion for existential and ethical reflection.
  • Transmigration and the concept of soul history:
    • The soul’s journey through various incarnations was tied to the belief in the continuity and reformulation of identity across lifetimes.
  • Pythagoras and music:
    • Pythagoras believed that musical tones corresponded to mathematical ratios; he studied music as an expression of numbers, not just as an art form.
    • The idea of music as a direct manifestation of numerical relations underlined his belief that nature is governed by mathematical harmony.
  • The tetractus (cross symbol) and number symbolism:
    • The symbol of the Pythagoreans often included the tetractus, formed from the first four numbers arranged as a geometric figure.
    • The first four numbers (1, 2, 3, 4) are considered fundamental, and their arrangement in a triangle yields a symbolic representation of number theory.
  • Number theory and the idea that numbers are geometric units:
    • Numbers can be represented as shapes; a point is dimensionless (0D), a line is 1D (requires two points), a triangle is the simplest 2D shape (requires three points), and a solid is 3D (four points define a tetrahedron).
    • All mathematics can be described in terms of these four categories (point, line, shape, solid).
  • The claim that “one is not a number”:
    • For the ancient Greeks, the unit (1) was not considered a number; the first true number is two. Numbers can be built from units, but one itself is a foundational unit rather than a number in the usual sense.
    • Zero did not exist in their number theory according to the tradition referenced here; its concept developed later in other cultures (often attributed to Indian or Arabic science; in the West, it became integrated after the medieval period).
  • The notion of numbers and geometry:
    • Numbers are tied to geometric representations; there is a historical linkage between arithmetic and geometry in early Greek thought.
    • Plato’s approach to atoms and elements drew on geometric shapes as rudimentary models of physical reality.
  • Cosmology and number:
    • Pythagoreans proposed a cosmology with a central fire (not the Sun) and five known planets (Mercury, Venus, Mars, Saturn, Jupiter) circling it; Earth was not counted among the planets in that scheme.
    • There was also a counter-Earth (a hypothetical Earth on the opposite side of the cosmos, invisible from our vantage point).
    • The realm of fixed stars was conceived as a rotating celestial dome; the stars appeared fixed relative to one another, with planets moving relative to the stars.
    • The model included a hierarchical, ordered cosmos with a cosmic architecture tied to number and harmony.
  • The number 10 and mechanical considerations:
    • Aristotle argued that there was no mechanical necessity for the number of celestial bodies to be ten; the ten-planet arrangement was, at least in part, chosen to reach the number 10 because of aesthetic or mathematical reasons rather than empirical necessity.
    • The idea that “ten” is a significant number appears in the Pythagorean cosmology as part of their numerological thinking.
  • Harmony of the spheres / music of the spheres:
    • The cosmic system was imagined as an ordered, harmonious whole in which celestial bodies produce a musical concordance (the harmony of the spheres), though humans cannot hear it directly due to our finite perception.
    • Modern astroacoustics (a 20th–21st century field) studies notes or sounds produced by astronomical objects to understand their properties; this echoes the ancient intuition that cosmic order has mathematical, sound-like structure.
  • Pre-history of the field: the “physicists” label and the idea that nature is numbers:
    • The ancient Greeks’ physics was a search for the fundamental principle (archê) of nature; for Pythagoreans this principle was number.

The philosopher’s toolkit: the vocabulary of form, reality, and knowledge

  • Forms vs appearances:
    • The world of Forms (Ideas) is timeless, unchanging, and truly real; the world of appearance is changing and less real in the Platonic view.
  • The term “entity” (Being) vs “beings”:
    • The world of objects that exist in space and time (beings) participates in the Forms but is not identical with them; appearances are imperfect copies of the Forms.
  • Tenets, dogma, and skepticism:
    • Tenet: a doctrine or teaching (Latin teneo, to hold).
    • Dogma: a belief treated as incontrovertibly true, often taught as doctrine.
    • Skepticism challenges the certainty of dogmatic claims and the possibility of achieving knowledge; it emphasizes suspension of judgment and the avoidance of dogmatic commitments.

Key terms and references to remember

  • Phusis: nature in Greek; origin of the term physics; natural philosophy.
  • Metempsychosis: transmigration of souls; soul passes from one body to another after death.
  • Reincarnation: synonymous with metempsychosis in many contexts; used interchangeably here.
  • Eternal recurrence: the belief that all events recur in an infinite cycle; a concept associated with Pythagoras and later with Empedocles and Nietzsche.
  • Tetractus: symbol formed by the first four numbers in Pythagorean numerology; a visual representation of number symbolism.
  • Counter-Earth: a hypothetical Earth placed on the opposite side of the cosmos; not visible from our vantage point.
  • Fixed stars: stars considered fixed on a celestial dome; used to explain planetary motions before the heliocentric model.
  • Neoplatonism: later, dogmatic interpretation and development of Platonic ideas; a later revival/dogmatization of Platonism.
  • One as not a number: a standard of early Greek number theory; two is the first true number; zero is absent in the ancient Greek system discussed here.

Connections to broader history and philosophy

  • Pre-Socratic physics (physicists) laid the groundwork for natural philosophy and science; Pythagoras’ numerology framed later mathematical approaches to nature.
  • Plato integrated mathematical knowledge into a robust theory of knowledge via the Forms, influencing later epistemology and metaphysics.
  • Neo-Platonism revived and reinterpreted Platonic ideas in a system that maintained a hierarchical, numerically structured cosmos.
  • The skeptical tradition (Academic skeptics and Pyrrhonists) challenged the certainty often claimed by earlier schools, pushing philosophy toward method, argumentation, and the avoidance of dogmatic stances.
  • The historical transmission of ideas about Pythagoras (via Sextus Empiricus and others) is largely through secondary sources and hagiography, complicating the reconstruction of the original doctrines.

Practical and ethical implications discussed in class

  • Skepticism as a stance: rejecting dogma can foster open inquiry and critical thinking, but can also produce epistemic uncertainty; the balance between seeking truth and avoiding dogmatic commitment is a central tension.
  • The Platonist distinction between permanence (Forms) and change (appearances) invites reflection on how we know and what constitutes real knowledge, with ethical implications for how we pursue virtue, beauty, and justice.
  • The Pythagorean emphasis on numbers and harmony suggests a view of the world as intelligible and potentially knowable through rational analysis and mathematical structure; this has long-term implications for science, mathematics, and philosophy.

Quick recap (for study reference)

  • Realism vs nominalism; monism vs dualism.
  • Dogmatists vs Academics vs Pyrrhonists; Sextus Empiricus; the nature of skeptical inquiry.
  • Plato’s two worlds; Forms vs appearances; permanence vs flux.
  • Presocratics as physicists; nature as phusis; Pythagoras as idealist; number as the basis of reality.
  • Metempsychosis, reincarnation, and eternal recurrence in Pythagorean thought and later associations with Nietzsche.
  • Music, harmony, and the harmony of the spheres; numerical ratios in music as a reflection of cosmic order.
  • The limits of demonstration in skepticism; the role of arguments that may be used without commitment to their truth.
  • The origin of words and concepts: tenet, dogma, hagiography, neopythagoreanism; the evolution of scientific and philosophical ideas across time.

Quick pop quiz ideas (as introduced)

  • Differentiate realism and nominalism with examples.
  • Explain the three types of philosophers described by Sextus Empiricus and how they differ on knowledge and truth.
  • Summarize Plato’s two-world theory and provide an example illustrating the Forms vs appearances distinction.
  • Describe Pythagoras’ view of nature as number and list some of the key philosophical implications (e.g., music as numbers, harmony, and the tetractus).
  • Explain metempsychosis and eternal recurrence and how they relate to Pythagorean thought and later thinkers like Nietzsche.
  • Outline the basic cosmology attributed to the Pythagoreans (central fire, five listed planets, Earth and counter-Earth, fixed stars).
  • Discuss why the first four numbers are treated as foundational in Pythagorean mathematics and what is meant by the claim that one is not a number.
  • Clarify the term hagiography and why Pythagoras’ writings are not extant in his own words.