PHILOSOPHY 100
(Ted Stolze)
Notes on James Rachels,
Problems from Philosophy
Chapter Ten:
Our Knowledge of the World around Us
Four Positions
on the Mind’s Relationship to the External World
•
Direct Realism (Aristotle, the Buddha)
•
Cartesian Theological Realism
•
Subjective Idealism (George Berkeley)
•
The Commonsense View (Indirect Realism)
Direct Realism (1)
“Seeing is a way of getting information about the world
around us. But it is not a two-step process, in which we first
get information about ‘sense-data’ and then move from that
to information about the tree. Instead, it is a one-step
process of seeing the tree. That’s how we know the tree is
there” (p. 133).
Direct Realism (2)
Mind <= Physical World
An Objection:
Cases of Perceptual Ambiguity
• Muller-Lyer Illusion
• Ponzo Illusion
• The Necker Cube
• Café Wall Illusion
• Ouchi Illusion
• Kanizsa Triangle
• E.G.Boring, “My Wife and My Mother-In-Law”
• Joseph Jastrow’s Duck-Rabbit
• Rex Whistler’s Reversible Faces
• The Thatcher Illusion
Müller-Lyer Illusion
Ponzo Illusion
The Necker Cube
Café Wall Illusion
Ouchi Illusion
Kanizsa Triangle
E.G.Boring, “My Wife and My Mother-InLaw”
Joseph Jastrow’s Duck-Rabbit
Rex Whistler’s (1905-1944) Reversible
Faces
The Thatcher Effect/Illusion
(An illusion of how it becomes difficult to detect local feature changes in an upside down face, despite identical changes
being obvious in an upright face. It was created by Peter Thompson in 1980 and is named after former British Prime
Minister Margaret Thatcher, on whose photograph the effect has been most famously demonstrated.)
Cartesian Theological Realism (1)
Mind => (Systematic Doubt) => Cogito => God => (Nondeceiving God) => Physical World
Cartesian Theological Realism (2)
• The Dream and Evil Demon Arguments
• Cartesian Argument for the Cogito
The Brain in a Vat Thought Experiment
INPUTS =>
=> OUTPUTS
Idealism (2)
Mind => (God) => “Physical World” (Phenomenal World)
Idealism (I)
Reality is constituted entirely of minds and their ideas, which
are mental representations of objects.
Objections to Subjective Idealism
•
Runs contrary to experience (e.g. of dishwashers)
•
Have to assume, or prove, the existence of a nondeceiving God
•
Makes scientific, artistic, or political practice
unintelligible, e.g. cannot distinguish between
appearance and reality
 (http://www.motherjones.com/mojo/2013/03/great-american-inequality-
video)
Vision and the Brain
Perception isn’t a passive process: “The mind does not simply
record what passes before it; instead, the mind actively
interprets experience according to certain built-in principles.
Therefore, what we think of as ‘simple’ perception is actually
the result of a complicated interpretation of the sensory data”
(p. 134).
The Commonsense View (1)
“We have experiences such as ‘seeing a tree’ or ‘hearing a
cricket’ because our bodies interact with a physical world
that includes things like trees and crickets. The world
impinges on our sense organs, causing us to have
experiences that represent the world to us in a fairly
accurate way. The physical world exists independent of
us—that is, it would exist even if we didn’t exist, and it
continues to exist even when we are not observing it” (p.
137).
The Commonsense View (2)
Mind <= Brain <= (Bodily Interaction) <= Physical World
Objections to the Commonsense View
•
•
“Dissolving World” thought experiment (pp. 129-30)
Brain in a Vat revisited