The Origin of Knowledge in Experience.
John Locke is the founder of modern empiricism. He argued that the mind is a "Tabula Rasa" (blank slate) at birth.
Locke argued that even our most complex ideas are built from these simple bricks of experience.
To explain the relationship between objects and our minds, Locke distinguished two types of qualities:
| Primary Qualities | Secondary Qualities |
|---|---|
| Exist in the object itself. | Exist only in the mind of the perceiver. |
| Inseparable from matter (Shape, Motion, Number). | Power of the object to produce sensations (Color, Smell, Taste). |
| Objective and measurable. | Subjective and variable. |
Berkeley took Locke's logic further. He argued that if secondary qualities exist only in the mind, then primary qualities (like shape) also exist only in the mind. There is no such thing as "matter."
"Esse est Percipi" (To be is to be perceived). Objects are just collections of ideas. Does a tree exist if no one is there? Yes, because God is the permanent perceiver who holds all ideas in existence.
Hume is the most radical empiricist. He divided all mental contents into two categories:
Hume’s "Fork": If an idea cannot be traced back to an impression, it is a "sophistry and illusion."
Hume used his empiricist method to challenge the foundations of human thought: