Plato believed that true knowledge comes from comprehending eternal, unchanging forms/ideas that represent concepts like beauty, justice, and goodness. He used three similes - the Sun, the Line, and the Cave - to explain his Theory of Forms. The Sun simile portrayed the form of the Good as the source of truth, like the sun provides light. The Line simile depicted different levels of understanding moving from images to forms. The Cave simile represented people trapped in a cave seeing only shadows on the wall, unable to comprehend true reality outside. Plato used these similes to illustrate his view that true knowledge comes from rational understanding of the forms, not from sensory experience.

1. Plato’s Theory of Forms, and
the Sun, Line and Cave
A falasafaz! presentation
1

2. Plato
What is justice?
What is the ideal
state?
What is the human
soul?
What is
knowledge?
What is reality?
2

3. Understanding Plato
• How does Plato
understand the nature
of reality?
• What is the relationship
between existence,
knowledge, and virtue?
• How successful are
Plato’s Sun, Line & Cave
similes?
3

4. Plato’s overall position
• Metaphysics
(Reality)
• Epistemology
(Knowledge)
• Ethics
(Good)
THE
THEORY
OF
FORMS
4

5. What is real?
5
Appearance Reality
• Sensations
• Empirically
observable
data
• Particular
examples of
‘X’
• Beyond
senses
• Mind/reason
• ‘The Forms’
• ‘The X-in-itself’

6. The Forms
6
Particular beautiful things

7. The Similes/Allegories
7
The Sun
Republic Bk VI 507a
The Divided Line
Republic Bk VI 509d
The Cave
Republic Bk VII 514a

8. The Sun
8
Source The Sun The (Form of the) Good
Provides what? Light, growth
Reality, truth – ‘light of
reason’
Where? Sensible world Intelligible World
In order to… See Know
With what?
Objects
i.e. ‘particulars’

9. The Divided Line
9
Objects Epistemic States
Forms
Physical Objects
Shadows /
Images
Dialectic
Belief
A
B
C
D
Mathematical
Reasoning
Illusion
Visible Realm Intelligible Realm
KNOWLEDGE OPINION

10. The Cave
10

11. Evaluating Plato
• What are the similes
meant to achieve? How
successful are they?
• What are Plato’s
arguments? How
persuasive are they?
• What objections can we
identify and develop?
11

12. This work is licensed under the Creative Commons Attribution-
NonCommercial-ShareAlike 2.0 UK: England & Wales License.
To view a copy of this license, visit
http://creativecommons.org/licenses/by-nc-sa/2.0/uk/ or send a letter
to Creative Commons, PO Box 1866, Mountain View, CA 94042, USA.
12