An Introduction to Philosophy Informative Summary


This book serves as a comprehensive introduction to the field of philosophy. Fullerton begins by tracing the historical evolution of philosophy from its early Greek origins to the modern period. He highlights the shift from viewing philosophy as synonymous with all knowledge to its present focus on reflective thought and specific problems like logic, psychology, ethics, and metaphysics. The text then delves into key problems surrounding the external world, questioning its very existence and examining our perception of it. Fullerton analyzes the distinction between sensations and things, appearances and realities, and explores the concepts of space and time. He then shifts focus to the nature of mind, questioning its existence as immaterial and separate from the body, and exploring the argument for the existence of other minds.

Fullerton examines different philosophical approaches to these issues, including realism, idealism, monism, dualism, rationalism, and empiricism. He criticizes specific philosophical doctrines like representative perception, idealism, and panpsychism, while advocating for critical empiricism, a cautious and analytical approach to examining experience. Fullerton concludes by emphasizing the value of studying philosophy, particularly its history, as a means to cultivate clear thinking, broaden perspectives, and gain a deeper understanding of ourselves and the world around us.

Key Findings:

  • The meaning of philosophy has evolved: Originally encompassing all knowledge, philosophy now focuses on reflective thought and specific problems related to the mind, the external world, and their relationship.
  • The existence of the external world can be doubted: Psychological and philosophical arguments raise serious questions about our ability to directly perceive the world outside our minds.
  • Distinguishing between sensations and things is crucial: The perceived world is not simply a collection of sensations; a real distinction exists between subjective experiences and objective things.
  • The concepts of reality, space, and time are complex: These fundamental notions are open to different interpretations and raise challenging philosophical problems.
  • The nature of the mind and its relation to the body are debated: Interactionism and parallelism offer contrasting views on how the mind and body connect and influence each other.
  • The argument for other minds rests on analogy: We infer the existence of other minds based on our own experiences, but the strength of this argument depends on the degree of similarity between individuals.


  • What philosophy is and how it has evolved over time: Readers will understand how the scope of philosophy has changed and its current focus on reflective thought and specific key problems.
  • The nature of reflective thought and its distinction from common thought and science: Readers will learn how philosophical inquiry delves deeper into fundamental concepts and assumptions that are often taken for granted.
  • The key problems that philosophers grapple with, including the existence of the external world, the nature of mind, and the relationship between mind and body: Readers will engage with these fundamental questions and appreciate their complexity and significance.
  • The major philosophical theories that have emerged to address these problems, such as realism, idealism, monism, dualism, rationalism, and empiricism: Readers will learn the defining characteristics of these schools of thought and how they offer contrasting perspectives on the world and the mind.
  • The importance of critical empiricism: Fullerton advocates for a cautious and analytical approach to philosophical inquiry, emphasizing the need for rigorous analysis and a willingness to revise conclusions in light of new evidence.
  • The value of studying philosophy: Readers will learn how philosophy can cultivate clear thinking, broaden perspectives, and contribute to a richer understanding of ourselves and the world around us.

Historical Context:

The book was written in 1906, during a period of significant intellectual ferment and advancements in science. The rise of psychology as an independent science, advancements in physics like the discovery of radioactivity, and the growing influence of evolutionary theory all contributed to a reassessment of traditional philosophical doctrines. Fullerton’s work reflects this intellectual climate, engaging with these advancements and advocating for a more critical and empirical approach to philosophical inquiry.


  1. The first Greek philosophers were preoccupied with physical speculations: They sought to explain the world’s composition and origins, demonstrating an early scientific spirit.
  2. The Sophists raised questions about the nature of truth and morality: Their inquiries marked a shift towards reflective thought and the beginnings of mental and moral sciences.
  3. Plato and Aristotle had a broad view of philosophy, encompassing all areas of knowledge: They explored physics, ethics, psychology, politics, and more.
  4. Later Greek schools emphasized philosophy as a guide to life: Stoics, Epicureans, and Skeptics all sought practical wisdom based on their philosophical views.
  5. Medieval philosophy distinguished between knowledge attained through reason and revelation: Philosophy focused on what could be known through natural reason.
  6. Modern philosophy shifted towards observation and science: Bacon and Descartes, despite their broad views, championed a more empirical approach.
  7. The plain man assumes he directly perceives the external world: However, he also recognizes the distinction between ideas and things, leading to potential doubts.
  8. The psychologist’s distinction between ideas and things reinforces doubts about the external world: This analysis suggests we only know the world indirectly through mental representations.
  9. Sensations are experiences in relation to the body, while qualities of things are experiences in a different setting: This distinction is crucial for differentiating between the subjective and the objective.
  10. We distinguish between apparent and real aspects of the world: Berkeley’s analysis highlights the role of touch in defining the real world, while other senses offer appearances.
  11. Science regards even touch objects as appearances, revealing a deeper reality of atoms and molecules: This reveals a hierarchy of appearances and realities, with the more fundamental levels becoming the focus of scientific inquiry.
  12. Real space and time are aspects of the external world, not independent things: They represent the plan of the world and its changes, known through our experiences.
  13. Primitive conceptions of mind were materialistic, often associating it with breath or fire: This reflects an early stage of reflection where mind and matter are not clearly distinguished.
  14. Plato and Aristotle recognized the mind’s immateriality, particularly reason: However, they still struggled with the mind-body relationship and its implications for the soul’s existence.
  15. Modern common sense notions of the mind are largely inherited from past philosophical doctrines: The idea of mind as an immaterial substance, while prevalent, lacks clear experiential grounding.
  16. The interactionist view sees the mind and body as causally interacting: This approach faces challenges in explaining how an immaterial mind can affect material things.
  17. The parallelist view sees mind and body as correlated but not causally connected: This approach emphasizes the distinct nature of mental and physical phenomena while acknowledging their consistent relationship.
  18. We infer the existence of other minds based on the analogy with our own experiences: The strength of this inference varies depending on the degree of similarity between individuals.
  19. The mind-stuff doctrine assumes a universal distribution of rudimentary consciousness: This speculative idea lacks empirical support and rests on questionable assumptions.
  20. Mechanism and teleology offer contrasting views of the world: The former emphasizes mechanical laws, while the latter recognizes purpose and ends.


  1. Philosophy: Reflective thought aimed at examining fundamental concepts and assumptions about the world, the mind, and their relationship.
  2. Epistemology: The study of knowledge, examining its nature, scope, and validity.
  3. Metaphysics: The branch of philosophy that investigates the fundamental nature of reality, including existence, time, space, causality, and consciousness.
  4. Realism: The philosophical position that asserts the existence of an external world independent of our minds.
  5. Idealism: The philosophical position that asserts that reality is ultimately mental or spiritual in nature.
  6. Monism: The doctrine that the universe is ultimately composed of only one kind of substance or reality.
  7. Dualism: The doctrine that the universe is composed of two fundamentally different substances or realities, usually mind and matter.
  8. Rationalism: The philosophical approach that emphasizes the role of reason in attaining knowledge, often asserting the existence of innate ideas or truths accessible through pure reason.
  9. Empiricism: The philosophical approach that emphasizes the role of experience and observation in attaining knowledge, rejecting the notion of innate ideas.
  10. Pragmatism: A philosophical approach that evaluates ideas based on their practical consequences and usefulness.


  1. The staff in water appears bent but feels straight: This example, used by ancient skeptics, illustrates the potential for sensory illusions and raises questions about the reliability of our senses.
  2. Walking towards a tree, its appearance changes: This example highlights the distinction between apparent and real qualities of objects, with the touch-object serving as a reference for the real size and shape.
  3. The fire in the study undergoes changes both dependent and independent of the observer’s position: This example illustrates the distinction between changes in sensations and changes in the object itself, crucial for recognizing an objective world.
  4. The image of a barber’s pole in the mind seems extended but is referred to a non-extended mind: This example reveals the challenge of reconciling the apparent extension of mental images with the immateriality of the mind.
  5. The falling tile vs. walking up the street: This example illustrates the distinction between activity and passivity, linking activity to conscious purposes and ends.
  6. The interaction of billiard balls: This example is used to explain mechanical causality, where both cause and effect belong to the same physical order.
  7. The localization of sensations in the brain: This example demonstrates the reference of mental phenomena to their physical concomitants in the brain.
  8. The different perceptions of a tree at various distances: This example is used to explain the argument for the existence of other minds, based on interpreting bodily actions as we do our own.
  9. The Democritean explanation of mind as composed of fire atoms: This example showcases an early materialistic attempt to explain mental phenomena, highlighting its shortcomings.
  10. Descartes’ placement of the soul in the pineal gland: This example illustrates a more nuanced materialistic view of the mind, attempting to account for its immateriality while still locating it within the body.


Fullerton’s “An Introduction to Philosophy” provides a comprehensive and accessible introduction to the field, exploring its history, key problems, and major theoretical approaches. The text emphasizes the importance of critical reflection, careful analysis of concepts, and a willingness to revise conclusions in light of new evidence. Through exploring fundamental questions about the world, the mind, and their relationship, readers are encouraged to develop a deeper understanding of themselves and their place in the universe. Fullerton’s advocacy for critical empiricism emphasizes the need for a cautious and nuanced approach to philosophical inquiry, valuing both reason and experience while acknowledging the ongoing nature of the quest for knowledge.

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