John Locke

The rationalist/ empiricist debate

• Locke addresses a central debate and philosophy between those who believe [rationalist] that much important knowledge is in it and arises apart from the senses, (a priori), and those who believe that knowledge is primarily based on the five senses [empiricists]

The traditional rationalist argument

P1: There are certain foundational truths [e.g.
foundations of logic, math] which people
universally give assent to when they
understand the propositions.
• P2: Since people have vastly different
experiences, these truths could not have been
learned through experience.
• C: These truths must be innate and be learned
apart from experience

Locke’s Rebuttal

• There is no universal assent to such truths.
Even 2 + 2 =4 is sometimes rejected by
children and the mentally challenged.

• Even if there were universal assent to such
truths, it is possible that such assent is due to
the fact that we all live in the same physical
world which follows the same rules regardless
of the variety of experiences we all have.

Rejection of Innate Ideas 

• Locke argues that we come into the world as a ‘blank slate’ or ‘tabula rasa’

• Ideas are the objects of thinking

• Ideas are not innate but originally enter the mind through senses 

Blank slate/ Tabula rasa

Human mind is born without any ideas or knowledge, all knowledge and understanding our gain through sensory experiences and interactions with the environment

The two sources of ideas

• All ideas can ultimately be traced to sense perception

• However, after an idea has entered the mind, it can be accessed again via reflection

Simple Ideas 

Are the most basic features of ideas:

shapes, colors, sound, size taste

Complex Ideas

ideas combine multiple simple ideas:

A sour apple, a red-brick house

Through reflection, the mind can re-combine simple ideas

if the ideas of polkadots, lime, green, and a house have entered my mind through sensation, the man can rec combine these ideas through reflection into new complex ideas

Locke's Four Part Account of Sensation

• External objects

• Data from external objects(light, sound waves, smells)

• The sense organs of the perceiver

• Ideas in the perceivers mind

Kinds of knowledge

locke claims that our knowledge is only about ideas in the mind(rather than external objects), but which hopefully represent the external world accurately

Four Types of claims about Ideas

• Identity/diversity

• Relation

• Coexistence/necessary connection

• Real existence

Identity/diversity of an idea

• Identity: to understand what constitutes a particular idea[in fallible knowledge at least eternally, but not necessarily externally]

• Diversity: to understand what distinguishes a particular idea from other ideas

Relation

• The understanding of the connections(or lack of connections) between multiple ideas

• For example: the idea of a tree is affirmatively related to ideas such as greenness, leaves, trunk, wood, plants, forest

Coexistence

• Necessary connections that are true of all examples of a particular idea

• Some, but not all relations of an idea will also have necessary coexistence

• Example: the substance gold possesses a yellow color, a particular weight/density, Malleability

• The concept of effect, must have a cause, which procedes it

Real existence

• The knowledge that something actually exists in the external world(as opposed to being the radical or fictitious 

• Computers exist, humans, exist, aliens, or time travel may not exist, Harry Potter, and Santa do not exist

Three Degrees of knowledge

• Intuitive - Highest

• Demonstrative - Mind

• Sensitive - Lowest

Intuitive knowledge

• The highest level of certainty: there is immediate perception of the agreement or disagreement of two ideas

• example: black is not white, a circle is not a square, a triangle has three sides

• There is no doubt of such knowledge, such things are often referred to as true definition. Anyone who understand the concept would immediately sent the truth of the claim.

Demonstrative knowledge

• A high-level of certain: there is a perception of the agreement or disagreement of two ideas, but not immediately

• example: Every event must have a cause

• the three internal angles of triangle equal 180 degrees

Sensitive Knowledge

• A much lower level of certainty. Our empirical
  knowledge of particulars…. Immediate
  knowledge of our five senses.
  • “There are at least three people in this room”
  • “Professor Silverman is wearing a green shirt”
  • “The table in front of me is rectangular”

The Challenge

Sensitive knowledge concerns particular
objects.
• Intuitive and demonstrative knowledge
concerns universal claims.
• Most important knowledge requires
combining a universal claim with a particular
claim…. “Humans are mortal, Socrates is a
human.”, “Rectangles have 180 degrees, this
wall is a rectangle.”

Primary Qualities of Objects:

Mind
Independent Properties of Objects

• Example: size, shape, weight

Secondary qualities of objects

properties that do not reside in the object itself

Example: color, sound, texture, taste, smell

The famous question

if a tree falls in the woods and no one is there to hear it, does it make a sound?

• Locke’s Answer: NO

Rejection of skepticism of external world

Common Sense: Thrust your hand into the fire

Primary Qualities of Objects

God: Exists and is not deceiver 

Rejects ontological argument for God and offers his own cosmological argument