An Empiricist Theory of
Knowledge
Locke’s Theory of Knowledge
Lecture 6
The Cartesian Theatre
No innate ideas – Theory simplification
• Locke’s reflection on knowing starts with the
problem of theories
– Given two explanations the one that is most likely to
be true is the simplest
– Is it possible to construct an explanation of
knowledge without using the notion of innate ideas
• According to Locke, “yes”, is one starts with a
simple concept (model) of the mind
The tabula rasa – The blank slate
• Imagine the mind like a blank slate on which
nothing is written (without any innate ideas)
– “Let us suppose the mind to be, as we say, white
paper, void of all characters, without any ideas: How
comes it to be furnished? To this I answer in one
word, from EXPEREINCE.” (John Locke, EHU)
The mind is like a blank slate
informed only by sense
experience and acts of reflection
Evidence for Locke’s model (EHU 2:1:6)
• Children show no evidence of innate ideas. They
appear to learn their ideas
– Copy from adults
– Education
– Personal experience
• If a child were kept in a room with no color would
have no idea of color
• So by “degrees” their minds are furnished with
ideas
Sensation & Reflection are the
origin of all ideas (and knowledge)
• Sensation
– Sense experiencing
– So sensation = the act of
sensing
– External (to
consciousness) material
things are the objects of
sensation
• Reflection
– The mind’s experience of
its own operations of
thinking, believing,
doubting, reasoning etc.
– The “internal” (to
consciousness) correlate
of sensing
– The mind’s operations
are the objects of
reflection
So . . . concluding argument
• All ideas originate with either
– Sensation (ideas of the sensible reality); or
knowledge of external objects
• Notice external objects furnish ideas of sensible things
– Reflection (ideas of the mind’s operation); or
knowledge of the mind’s operation (activities)
• Notice: the mind furnishes the understanding with ideas
about the mind’s own operations.
• There is a potential problem here. What is it?
Key distinctions
• Simple and complex ideas
– Simple ideas originate in any one sense that cannot be
broken down into simpler entities (e.g. yellow)
– Complex ideas are combinations of simple ideas (apple =
spherical-red-sweet) created by the mind
• Primary and secondary qualities
– Primary quality are characteristics of external objects
(extension, size, shape, location)
– Secondary qualities exist only in the mind yet caused by
features of external objects (colors, sounds, tastes)
• Notice qualities inhere in things; ideas in minds
Locke’s theory of idea formation
EHU 2:7:7-21
All ideas from sensation or reflection
Passive impression
Sense data representation
Sensory experience
(seeing, touching, tasting,
smelling)
Reflection (thinking,
doubting, comparing,
coming to an opinion)
Active reflection
Ideas, concepts, explanations, etc.
sensation-reflection-operation-idea
sensation reflection simple idea operation complex idea
Sense data  blue 
color: blue
Sense data  stripe 
form: stripe
Combination  blue stripe
All ideas come from sensation or
reflection
Experience
sensation
reflection
Passive
mind
Simple ideas
Complex ideas
Active mind
Representationalism
• On this account the mind REPRESENTS reality
(the external world)
– What we know are ideas NOT reality in itself
– Best analogy is a photographic process in which
what is external to the camera ‘imprints’ an image on
the film.
What are we doing when we are
knowing?
• Passively receiving sense impressions
• Assembled as representations of simple ideas
• Combined, compared, distinguished by active
reflection into complex ideas
• Ideas “correspond to” the external world (or
reality)
What do we know when we do that?
• IDEAS that represent the external world
Idea of a cactus in
the sun
=
Knowledge of
cactus in the sun
Locke’s Epistemological Dualism
Our ideas correspond to objects in the world
Corresponds to
Physical object
Reality in itself
External world
Mental object
representation or
idea, the internal
world
The Egocentric Predicament
• If ideas correspond to the external world, how can we
verify the correspondence?
• The is a version of the “bridge problem”
• There is “no place” outside the mind where one can
verify the correspondence of the idea to the object
represented
• So while Locke overcomes Cartesian solipsism, he has
his own version of the ‘egocentric predicament’.
Locke’s Contribution
• The senses play a role in knowing by providing data
from an “external world” - the “to be known.”
• The ‘external world’ (reality) imposes itself on
consciousness. However, what is ‘imposed’ (impressed
on the mind) are ideas.
– As we have noted there is no means to verify the
correspondence of idea and reality the idea represents.
• The mind actively relates the data together.
– So the mind is ACTIVE in acts of knowing.