Chapter 2: Empiricism - Detailed Study Guide

The Empiricist Tradition

• Core Claim of Empiricism:

  • Empiricism is a foundational family of ideas that has shaped philosophical thinking about science more than any other.
  • The fundamental summary claim of empiricism is that experience is the only source of knowledge.

• Historical Origins and Development:

  • While the idea has a long history, classical empiricism developed predominantly during the seventeenth and eighteenth centuries.
  • Key classical empiricist philosophers include John Locke, George Berkeley, and David Hume.
  • Classical empiricism was built on a "sensationalist" theory of mind:
  • Sensations, such as patches of color and sounds, appear in the mind and represent everything to which the mind has direct access.
  • Thought functions primarily to track and respond to patterns within these sensations.
  • In modern terms, classical empiricism viewed the mind as a pattern-recognition device.

• Skepticism and Phenomenalism:

  • Empiricism has historically faced challenges with skepticism—the view that we cannot know anything, or can know much less than usually supposed, about the world.
  • Two prominent forms of skepticism in this context:
  • External World Skepticism: Questions whether knowledge is possible regarding a physical world that lies behind sensory input.
  • Inductive Skepticism: Made vivid by David Hume; questions why patterns found in past experience should be expected to hold in the future.
  • Phenomenalism:
  • Many empiricists conceded to external world skepticism, arguing that humans only interact with sensations and that it is unnecessary or meaningless to postulate objects behind them.
  • Defines the concept of "the world" merely as a patterned collection of sensations.
  • Phenomenalism gained significant popularity during the nineteenth century.
  • John Stuart Mill defined matter as "a Permanent Possibility of Sensation" (1865, p. 183).
  • Ernst Mach, an Austrian physicist and philosopher whose work influenced Albert Einstein, illustrated phenomenalism by drawing the world strictly as it appeared through his left eye, including his brow, nose, and elegant mustache. Mach asserted that all that exists is a collection of observer-relative sensory phenomena.

• The "Veil of Ideas":

  • Phenomenalism arises from viewing the mind as trapped behind a "veil of ideas" or sensations with no access to an external reality.

  • Rationalism vs. Empiricism:

• Historical Debate (17th–18th Centuries):

  • Rationalists (e.g., René Descartes, G. W. Leibniz): Maintained that pure reasoning independently of experience offers a path to knowledge, citing mathematics as a prime example.
  • Empiricists (e.g., John Locke, David Hume): Maintained that experience is the sole means to discover what the world is like.

• Immanuel Kant's Synthesis (Late 18th Century):

  • Proposed that all thinking involves an interaction between sensory experience and preexisting mental structures.
  • Argued that foundational concepts like space, time, and causation cannot be derived from experience, as they are necessary prerequisites for organizing experience.
  • Maintained that mathematics provides genuine, informative knowledge that does not require empirical justification ($a\,priori$ knowledge).

• Modern Usage:

  • In twentieth-century philosophy of science, "rationalism" shifted to describe a broad confidence in human reason and was often compatible with empiricism.

  • Broader Intellectual and Political Tendencies:

• Historically, the empiricist tradition has exhibited three key tendencies:

  1. Pro-science attitude.
  2. Worldly and secular rather than religious orientation (with notable exceptions, such as Bishop George Berkeley).
  3. Politically moderate or liberal stance.

• Examples embodying all three traits include David Hume, John Stuart Mill, and Bertrand Russell.

The Vienna Circle

• Formation and Context:

  • Developed in Europe following World War I as a movement of scientifically minded thinkers opposed to traditional metaphysical philosophy.
  • Founded in Vienna, Austria, by Moritz Schlick and Otto Neurath.
  • Rudolf Carnap was another central figure in developing its doctrines.
  • The group was formally named the Vienna Circle and paid homage to Ernst Mach.

• Terminology:

  • Logical Positivism: The primary name for the Vienna Circle's movement (derived from Auguste Comte's nineteenth-century positivism).
  • Logical Empiricism: Often used interchangeably, or specifically to denote the later, more moderate phase of the movement compared to earlier, more radical logical positivism.

• Philosophical Influences:

  • Breakthroughs in early twentieth-century physics, particularly Albert Einstein's relativity theories.
  • Developments in formal logic, mathematics, and philosophy of language.
  • Ludwig Wittgenstein's Tractatus Logico-Philosophicus (1922): Provided foundational ideas on language that the positivists adapted and utilized.

• Targets of Opposition:

  • Post-Kantian German Idealism: Viewed by positivists as pretentious, obscure, dogmatic, and politically dangerous.
  • G. W. F. Hegel and Absolute Idealism:
  • Hegel posited history as a process wherein a "world spirit" achieves self-consciousness.
  • Prioritized the state over the individual, feeding into nationalist ideologies.
  • Claimed reality as a whole is spiritual or rational ("absolute idealism").
  • Hans Reichenbach (The Rise of Scientific Philosophy, 1951) criticized Hegel's statement that "Reason is substance, as well as infinite power, its own infinite material underlying all the natural and spiritual life…", arguing that obscure language was used to conceal a complete lack of factual content.
  • Martin Heidegger and Existentialism:
  • Author of Being and Time (1927).
  • Summarized by Thomas Sheehan (1998) as arguing that "mortality is our defining moment, that we are thrown into limited worlds of sense shaped by our being-towards-death, and that finite meaning is all the reality we get."
  • Prioritized practical coping over scientific knowledge and engaged in obscure analyses of "Being" and "Nothing."
  • Opposed liberal democratic politics and joined the Nazi Party in 1933.
  • Rudolf Carnap famously subjected Heidegger's writings on "Nothing" to logical analysis to demonstrate their lack of meaning.

• Ideological Values and Dispersal:

  • Promoted Enlightenment values: reason over obscurity, logic over intuition, and internationalism.
  • Advocated for a universal, precise language for clear scientific communication.
  • Social/political links: Otto Neurath and others were democratic socialists connected with modern movements like the Bauhaus architecture movement.
  • Spread to England: A. J. Ayer's Language, Truth, and Logic (1936) introduced positivism to Britain, leading English philosophy (alongside G. E. Moore and Bertrand Russell) away from absolute idealism.
  • Impact of World War II:
  • Positivists were persecuted by the Nazi regime due to socialist and Jewish backgrounds.
  • Moritz Schlick was assassinated in 1936 by a former student.
  • Key members emigrated to the United States (including Rudolf Carnap, Hans Reichenbach, Carl Hempel, and Herbert Feigl), transforming post-war American philosophy into a dominant, albeit moderated, analytic tradition.

Central Ideas of Logical Positivism

• Language-Based Empiricism:

  • Unlike classical empiricism, which focused on psychological mental states, logical positivism grounded its philosophy in theories of language.

• Verifiability Theory of Meaning (Verificationism):

  • Definition: The meaning of a sentence consists in its method of verification.
  • Core Principle: Knowing the meaning of a sentence entails knowing how to verify it; if a sentence has no possible method of verification, it lacks meaning.
  • Key Attributes:
  • Verification requires observational evidence (sensory experience).
  • Testability is a preferred term, as testing applies to both truth and falsity.
  • Refers to testability in principle, not in practice.
  • Does not require absolute conclusive verification—only that observational evidence can count for or against the statement.
  • Applies strictly to "factual meaning" (statements asserting facts about the world), excluding commands, emotional expressions, and poetry.
  • Philosophical Function: Used as a tool to dismiss traditional metaphysics, theology, and much of ethics as factually meaningless.

• The Analytic/Synthetic Distinction:

  • Analytic Sentences: True or false purely by virtue of the definitions of the words involved, independent of empirical facts (e.g., "All bachelors are unmarried"). They represent empty truths with no factual content and are not governed by the verifiability principle.
  • Synthetic Sentences: True or false based on word meaning and actual empirical facts about the world (e.g., "All bachelors are bald").
  • Mathematics and Logic:
  • Logical positivists classified all logic and pure mathematics as analytic.
  • Mathematical statements record conventions for symbol manipulation rather than factual descriptions of nature.
  • Rejected Kant's notion of synthetic $a\,priori$ knowledge.
  • Reinterpretation of Geometry:
  • Einstein demonstrated that physical space is non-Euclidean.
  • Positivists divided geometry into two distinct components:
    1. Pure Mathematics: Analytic, non-empirical description of formal geometrical systems.
    2. Applied Physics: Synthetic, empirical claims testing which geometrical structure describes the physical universe.

• Observational vs. Theoretical Language:

  • Distinguishes between observational terms (e.g., "red") and theoretical terms (e.g., "electron").
  • Distinguishes observational statements ("The rod in front of me is glowing red") from theoretical statements ("Helium atoms each contain two electrons").
  • Internal Disputes on the Observational Boundary:
  • Moritz Schlick: Restricted observational language strictly to private sensory experiences.
  • Otto Neurath: Expanded observational language to include public physical objects, establishing an intersubjective foundation for science.
  • Rudolf Carnap: Adopted a principle of tolerance, allowing flexible boundaries depending on pragmatic linguistic needs.

• The Task of Philosophy and Logic:

  • Maintained that philosophy should be dedicated to the formal logical analysis of language, mathematics, and science.
  • Deductive Logic: Explores valid arguments where true premises guarantee a true conclusion.
  • Inductive Logic: A proposed formal theory of arguments where premises provide probabilistic support for conclusions without deductive certainty.
  • Scientific Fallibilism: Positivists explicitly acknowledged that science never yields absolute certainty and that empirical claims remain open to revision.

• Context of Discovery vs. Context of Justification:

  • Terminology introduced by Hans Reichenbach.
  • Distinguishes the logical analysis of scientific theories (Context of Justification) from the historical, psychological, and sociological processes of scientific creation (Context of Discovery).
  • Positivists restricted philosophy of science strictly to justification, dismissing history and psychology as empirical distractions.

• Operationalism and the Mariner Metaphor:

  • Operationalism: Formulated by physicist Percy Bridgman (1927); argued that scientific terms must be defined directly by specific operational testing procedures.
  • Otto Neurath's Mariner Metaphor: Science continuously rebuilds its conceptual framework while actively functioning, like "sailors who have to rebuild their ship on the open sea," replacing planks individually without ever grounding the vessel in dry dock.

Problems and Changes

• Internal Failures of Verificationism:

  • Formulating the verifiability principle to exclude metaphysics while preserving valid scientific laws proved logically problematic.
  • Conjunction Problem: If statement $A$ ("Metals expand when heated") is testable, then the conjunction $A \land B$ ("Metals expand when heated and the Absolute Spirit is perfect") is also testable, because if $A$ is false, $A \land B$ is logically false. Attempts to fix this flaw created additional technical paradoxes.

• Quine's Holism and "Two Dogmas of Empiricism" (1951):

  • W. V. Quine published a landmark attack on classical logical positivism.
  • Holism of Testing (Duhem-Quine Thesis):
  • Individual hypotheses cannot be tested in isolation from background assumptions.
  • Testing involves a complex network of claims, including assumptions about instruments, observer reliability, and auxiliary theories ($p \land q \land r \dots$).
  • An unexpected observational result indicates an error somewhere in the network, but cannot logically isolate which specific assumption failed.
  • Example: A unexpected barometer reading could mean the pressure-weather hypothesis is false, the barometer is faulty, or the observer made an error.
  • Quine's Metaphor: Theories "face the tribunal of sense-experience . . . as a corporate body."
  • Historical Oversight: While Quine targeted positivists for treating claims in isolation, logical positivists such as Feigl (1943), Carnap (1937), and Ayer (1936) had explicitly recognized holistic testing in print, though their verifiability principle failed to reflect it.

• Attack on the Analytic/Synthetic Distinction:

  • Quine argued that the analytic/synthetic distinction was an ungrounded "dogma."
  • Maintained that no statement is completely immune to empirical revision.
  • Web of Belief Model:
  • Human knowledge forms a single interconnected "web of belief" that contacts experience only at its boundaries.
  • Any belief within the web can be revised in response to recalcitrant experiences—even logical principles or mathematical claims (e.g., potential revisions to logic prompted by quantum mechanics).

Logical Empiricism and the Web of Belief

• Post-War Evolution into Logical Empiricism:

  • Maintained emphasis on logical analysis while abandoning radical anti-metaphysical rhetoric.
  • Replaced isolated verificationism with holistic theories of meaning: theoretical terms ("electron," "gene") derive meaning from their systemic position within an entire theoretical network.

• Feigl's Model of Theories (1970):

  • Described the "orthodox view" of scientific theories as a network of theoretical constructs (postulates, primitive concepts, defined concepts) linked to empirical concepts and anchored directly in the "soil" of experience.

• Theoretical Entities and Scientific Realism:
  • Carl Hempel's "The Theoretician's Dilemma" (1958): Highlighted the tension in empiricism between treating theoretical entities as mere tools for predicting observable patterns versus recognizing that scientific practice treats entities like electrons and genes as real.
  • Aversion to "Depths":
  • Positivists historically rejected "layered" views of reality, fearing a return to Platonic dualism (world of appearances vs. world of forms).
  • Carnap, Hahn, and Neurath (1929): "In science there are no 'depths'; there is surface everywhere."
  • Positioned prediction as the primary purpose of science to avoid positing unobservable realities.
  • Realist Critique:
  • Science routinely investigates real, unobservable structures across multiple continuous depths (e.g., genes, protons, quarks).
  • Herbert Feigl (1958) criticized positivists for being "dazzled by the admittedly tremendous importance of the evidential basis" and "myopically" flattening reality onto the surface of observational evidence.

Experience, Experiment, and Action

• Observation vs. Experimentation:

  • Richard Feynman (The Feynman Lectures on Physics): "The test of all knowledge is experiment. Experiment is the sole judge of scientific 'truth.'"
  • Contrast: Traditional empiricism emphasized passive observation, whereas scientific practice prioritizes active experimental manipulation.
  • Non-Experimental Science:
  • Highly successful fields like early modern astronomy relied primarily on systematic observation rather than experimentation.
  • Example: Edmund Halley successfully predicted the 1758 return of Halley's Comet using Newton's gravitational laws and historical observations.
  • Evolutionary biology originally developed through observational field work rather than experimental manipulation.

• The Neglect of Human Action:

  • Empiricist philosophy (including Quine's holistic model) focused on passive prediction while neglecting human action and world-building.
  • Two Primary Functions of Action in Science:
  1. Practical Application: Applying knowledge to manipulate the environment (e.g., bridge engineering, water purification).
  2. Active Experience Generation: Actions deliberately produce novel sensory experiences that would never occur passively (e.g., constructing particle accelerators).