The Non-Existence of the Physical World

Central Question:

Do things continue to exist when not observed?

References to historical philosophical inquiries into the nature of reality, particularly those of Rene Descartes, who famously doubted the certainty of existence of the external world, leading to his conclusion "I think, therefore I am."
Introduction of Bishop George Berkeley's radical philosophical view articulated in his 1710 work, A Treatise Concerning the Principles of Human Knowledge, which posits that the physical world does not exist independently of perception, a concept known as immaterialism.

Intuitive Perspective: Commonly held belief: people generally assume a physical world exists independently from their perception of it. This intuition is fundamental to our everyday experiences.
Observation of Properties: When observing an object, such as a banana, its intrinsic properties (e.g., color, shape, texture) become accessible through sensory organs such as the eyes and hands. Berkeley argues that these properties do not exist in isolation from observers.
Nature of Properties: Properties such as 'yellow' result from specific conditions of light reflecting off the object, emphasizing that these characteristics are contingent upon observation. Thus, without perceivers, the essence of objects may lack substance or definitive existence.

Definition of Existence: In Berkeley's view, existence is intrinsically linked to perception, encapsulated in the phrase: "To be, is to be perceived." Thus, an object's reality is determined by its presence in someone's perceptual experience.
Limits to Imagining Existence: One cannot form a coherent concept of an object’s existence without incorporating properties; for instance, a table that is not currently observed cannot be accurately described regarding its physical characteristics, such as color or size. This limitation places a profound question on the nature of reality itself.
Independence Misconception: The widespread belief that an object, like a table, exists independently of observers is criticized by Berkeley as a misunderstanding, where expectation of observation affects perceived reality.

Complications in Acceptance: A more nuanced understanding arises when contemplating the paradox: the inside of your house seems to cease to exist for you when you leave temporarily, challenging our ingrained perceptions of permanence in physical reality.
Berkeley's Stance: Berkeley contends that absence of perception equates to absence of properties; therefore, an object cannot be said to exist in any conventional sense if it is not perceived by anyone at any time.

Implication of Reality: Under Berkeley’s philosophy, dreams and hallucinations gain legitimacy as equally valid forms of reality, since both are rooted in perception, leading to questions about the nature of sanity and reality.
Physical Impact: However, if an object like a car exists outside one’s perception, its potential independent existence becomes evident when considering possible real-world consequences, such as the threat posed by an unseen vehicle. This exemplifies the crucial interplay between perception and actual risks.

God's Role: Berkeley incorporates a theological dimension, suggesting that God plays a pivotal role by ensuring coherence among various perceptions. If a driver does not perceive danger, it reflects a divine arrangement whereby God maintains logical reality, allowing perception to be trustworthy.
Issues with the Argument: Contingent questions arise from this perspective: What occurs if a person experiences a fatal event without perceiving it? This challenges the assurance of divine oversight, particularly in altered states of consciousness, such as those induced by hallucinogenic drugs.

Nature of Existence: The discourse prompts deeper contemplation of what it means to exist, suggesting that reality may depend more on perception than an objective, independently existing world.
Analogies and Theories: Berkeley's views can be analogized to abstract mathematical concepts, which can be seen as fundamentally necessary to understand the universe, even in the absence of irrefutable proof of their physical manifestation.