Three Dialogues Between Haylas and Philonous in Opposition to Sceptics and Atheists Informative Summary


 This text presents a classic philosophical dialogue between Hylas, a believer in material substance, and Philonous, a proponent of immaterialism. Throughout three dialogues, they engage in a rigorous examination of the nature of reality, focusing on the existence of matter and sensible qualities. Philonous systematically dismantles Hylas’s arguments by demonstrating that sensible qualities like heat, color, and even extension cannot exist outside of a perceiving mind.

Key points of Philonous’s arguments include the relativity of sensible qualities, their dependence on the perceiver’s state and context, and the logical inconsistencies arising from attributing them to an inert, unthinking substance. He concludes by presenting immaterialism as a more coherent and religiously sound alternative, offering a direct and immediate demonstration of God’s existence from the mere existence of the sensible world.

Key Findings:

  • Sensible qualities like heat, color, and sound are relative to the perceiver and cannot be attributed to inert matter.
  • The concept of material substance, as a substratum for sensible qualities, is incoherent and leads to logical inconsistencies.
  • The existence of the sensible world necessarily implies the existence of an infinite, omnipresent Spirit who perceives and sustains it.
  • Immaterialism offers a more coherent explanation of the natural world and provides stronger support for religious beliefs.


  • The Nature of Perception: The reader will gain a deeper understanding of how perception works and how our senses provide us with knowledge of the world. The text highlights the subjective nature of sensory experience and how it varies based on individual perspective and context.
  • Immaterialism: The reader will be introduced to the philosophy of immaterialism and its arguments against the existence of material substance. The text meticulously outlines the reasons why sensible qualities cannot exist outside of a perceiving mind and how this leads to the conclusion that only minds and ideas are real.
  • Arguments for the Existence of God: The reader will learn how the existence of the sensible world itself can be used as an argument for the existence of God. Philonous demonstrates that the perceived order, complexity, and beauty of the world require an intelligent and powerful Mind to sustain them.

Historical Context:

The text was written during the early 18th century, a period marked by significant philosophical and scientific advancements. The rise of Newtonian physics and the emphasis on empirical observation and reason challenged traditional metaphysical assumptions. Berkeley’s immaterialism emerged as a response to the perceived shortcomings of materialist explanations and aimed to provide a more coherent and religiously compatible understanding of reality.


  1. Intense heat is a type of pain: Intense heat is felt as a painful sensation, and pain cannot exist without a perceiving mind.
  2. Warmth is a type of pleasure: Warmth is experienced as a pleasant sensation, and pleasure, like pain, necessitates a perceiving mind.
  3. Tastes are subjective: Different individuals experience tastes differently, indicating that taste is not inherent in the object but a subjective perception.
  4. Odors are relative: What smells pleasant to one creature might be repulsive to another, proving that smell is a matter of perception, not an objective quality.
  5. Sound requires a medium: A bell struck in a vacuum makes no sound, demonstrating that sound needs a medium, like air, to travel and be perceived.
  6. Sound is a sensation: Sound, as we perceive it, is a sensation caused by vibrations traveling through the air and stimulating the auditory nerves.
  7. Colors are not inherent in objects: Objects appear different colors under different lighting conditions or when viewed through a microscope, indicating that color is not an intrinsic property of the object.
  8. Colors are perceived through light: Light, a thin fluid substance, carries color information through its motion and reflection, affecting our optic nerves.
  9. Microscopes reveal a different reality: Microscopes show colors and structures invisible to the naked eye, suggesting that the world perceived by different creatures can vary significantly.
  10. Secondary qualities exist only in the mind: Qualities like color, sound, taste, and odor are secondary qualities and are merely sensations existing in the mind.
  11. Primary qualities depend on perception: Primary qualities like extension, figure, and motion also change based on the perceiver’s perspective and cannot be considered inherent in objects.
  12. Extension is not absolute: A mite perceives the size of its foot differently from a human, proving that extension is not absolute but relative to the observer.
  13. Motion is relative to time perception: The speed of a moving object appears different based on the observer’s perception of time, making motion a relative experience.
  14. Solidity is relative to the perceiver: Hardness and resistance, components of solidity, are perceived differently by creatures with varying strength and physical capabilities.
  15. Abstract ideas of extension and motion are impossible: It’s impossible to conceive of extension or motion without associating them with specific sizes, shapes, or sensible qualities, indicating that abstracting them is not possible.
  16. Sensible objects cannot be conceived as unperceived: Thinking of a tree as unperceived is still an act of perception by the thinker, demonstrating that conceiving of something as unperceived is contradictory.
  17. Distance is not directly perceived: Distance is a line turned endwise to the eye and thus cannot be directly perceived through sight but learned through experience.
  18. Dreams demonstrate the subjective nature of perception: Just as dream objects appear distant without being physically so, the appearance of distance in waking life does not guarantee external existence.
  19. Material substance is an ultimately empty concept: Hylas’s attempts to define matter lead him to progressively empty and contradictory conceptions, demonstrating the inadequacy of the concept itself.
  20. The existence of the sensible world implies a mind: Since sensible objects are ideas, and ideas cannot exist outside a mind, the very existence of the world proves the existence of a Mind – God


  1. Material Substance: An unthinking, inert substance believed to be the underlying support for sensible qualities.
  2. Immaterialism: The belief that only minds and ideas exist, and that there is no material substance.
  3. Sensible Qualities: Qualities perceived by the senses, such as color, sound, taste, odor, texture, and temperature.
  4. Primary Qualities: Qualities believed to be inherent in objects, such as extension, figure, solidity, motion, and rest.
  5. Secondary Qualities: Qualities considered to be dependent on the perceiver, such as color, sound, taste, and odor.
  6. Idea: An immediate object of perception or thought.
  7. Spirit: An active, thinking substance, such as the human soul or God.
  8. Scepticism: The philosophical view that knowledge is impossible or that we can never be certain of anything.
  9. Phenomena: The appearances of things as perceived by the senses.
  10. Absolute Existence: Existence independent of any mind or perceiver.


  1. Hand in Water: A hand placed in lukewarm water feels warm to a cold hand and cold to a warm hand, demonstrating that temperature is not inherent in the water but a sensation.
  2. Pinprick vs. Burning Coal: Both cause pain, but we don’t attribute the sensation of pain to the pin or coal itself, suggesting a similar approach to other sensible qualities.
  3. Sugar and Wormwood: While sugar tastes sweet and wormwood bitter, this difference lies in our perception, not in inherent qualities of the substances.
  4. Bell in a Vacuum: A bell struck in a vacuum produces no sound, proving that sound is not a property of the bell itself but a sensation dependent on a medium.
  5. Microscopic View: A microscope reveals colors and structures invisible to the naked eye, demonstrating the subjectivity and limitations of our sensory perception.
  6. Jaundiced Vision: A person with jaundice sees everything yellow, highlighting how our internal state can alter our perception of color.
  7. Prism Experiment: A prism splits white light into different colors, showing that color is a property of light and not inherent in the object reflecting it.
  8. Caesar’s Picture: Two individuals, one familiar with Julius Caesar and one not, see the same image, but their thoughts are directed differently, proving that perception is not solely determined by sensory input.
  9. Mite’s Foot: A mite perceives its foot to be a different size than a human, demonstrating the relativity of size and extension.
  10. Dream Images: Objects in dreams appear distant without being physically so, suggesting that the appearance of distance in waking life does not guarantee external existence.


Berkeley’s “Three Dialogues” offers a compelling case for immaterialism by dismantling the concept of material substance and demonstrating the subjective nature of perception. The text argues that the existence of the sensible world directly implies the existence of an infinite, omnipresent Mind, offering a strong argument for the existence of God. While potentially challenging, Berkeley’s philosophy ultimately encourages a reliance on our senses while recognizing their dependence on a Divine Mind, presenting a view of reality that is both coherent and religiously significant. The reader is left with a renewed appreciation for the wonders of the perceived world and a deeper understanding of the role of mind and spirit in shaping our experience of reality.

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