• The form of the good:
• without knowledge of the Form of the Good (FOG), all other knowledge would be of no benefit (505-6)
• the FOG is the 'cause' of truth and knowledge.
• the FOG gives their being and essence to the objects of knowledge
• the FOG is not essence and transcends essence in dignity and power (509a-b)
• FOG is prior to everything else:
• epistemologically
• ontologically
• ethically
• The FOG probably is presupposed by the teleological explanation in Phaedo 97-99, the creation of the universe in Timaeus, and the theory of love in Symposium

First Round: Ethical and Political Considerations

• Text 1:
• The greatest study is the study of the Form of the Good, by participation in which just things and all the rest become useful and beneficial (505a)
• Text 2:
• If we do not know the Form of the Good, then even if without such knowledge we know everything else, it (knowledge of everything else) would be of no benefit to us, just as no possession would be (of benefit) without possession of the Good (505a-b)
• Text 3:
• If we know all things without knowing the Good, (this would be of no benefit because) we would not know (that) anything (is) beautiful and good (505b)
• Text 4:
• The Good is not (identical with) knowledge or pleasure. (505b-d)
  

• Plato rejects the ideas
  
• that the good is knowledge
  
• why? because when asked "knowledge of what," all that can be answered is "knowledge of the good" and it becomes circular and uninformative.
• One might ask why all knowledge is not good, and so why the answer couldn't be "knowledge of any thing": perhaps it is true that all knowledge is good, but maybe all good is not knowledge?
  
• the good is pleasure
• Why? because there are pleasures that are bad. If pleasure is the good, and some pleasures are bad, then the same things are good and bad (which seems like a contradiction).
• Perhaps there is a way around this: what if all pleasurable things are good insofar as they are pleasurable (i.e. if X is pleasurable but bad, that is because X has some bad quality other than pleasure).

• Text 5:
• Many people prefer what-appears-to-be-just-and-honorable-but-is-not, but no one prefers to pursue or possess what-appears-good-but-is-not. (505d-e)
• Text 6:
• every soul pursues the Good and does everything for its sake, divining what it is and yet baffled and not having an adequate apprehension of its nature nor a stable opinion about it as it has about other things, and because of this failing to have any benefit from other things (505e)
• Text 7:
• Our constitution will not be perfectly ordered unless the rulers know how just and honorable things are good and they will not know this unless they know the Good. 506a-b

• Platonic Principle 1:
  
• It is by virtue of participation in the Form F-ness or the F that anything which is F is F.
• The second part of Text 1 is an instance of this general principle.
  
• results from a lot of argument and debate about Plato: it seems that a sensible is Good because it participates in the Form of whatever it is, and that Form participates in the Form of the Good, and so the sensible is good. A Form is good because it participates in the Form of the Good.
• Platonic Principle 2:
• If we do not know F-ness or the F, we do not know that anything is F.
• Text 3 is an instance of this general principle.

• Texts 6, 1, 2 and 7 give study of the Form of the Good a privileged position over all other forms.
• If we don't know the Form of the Good, we are like archers devoted to hitting targets, but unable to see their target clearly and also unable to tell if they hit their target or something else.

Second Round: Epistemological and Ontological considerations

• Text 8: As the Good is in the intelligible region to reason and to the objects of reason, so is the Sun in the visible world to vision and the objects of vision. 508c
• Text 9: The Sun (by its light) gives the objects of sight their visibility and the faculty of sight its vision: similarly, the Form of the Good gives the objects of reason their truth and to reason its knowledge of them (508b, 508d-e)
• Text 10: The Sun is the cause of light and vision, and light and vision are sunlike but not identical with the Sun; similarly, the Form of the Good is the cause of truth and knowledge, and truth and knowledge are like the FOG but they are not identical with it. 509a)
• Text 11: The Sun not only furnishes the visible the power of visibility but it also provides for their generation and growth and nurture, though it is not itself generation: similarly, the objects of knowledge receive not only their being known from the presence of the Good, but also their being and essence (reality) comes from it, though the Good is not essence but still transcends essence in dignity and surpassing power. 509b

• Whereas the 'first round' dealt with relations between FOG and good things, the 'second round' deals with relations between FOG and Forms.
• The texts above justify the following claims:
• FOG is the cause of the knowability of (other)Forms
• FOG is the cause of reason's knowing (other)Forms
• FOG is the cause of the being and essence (reality) of (other) Forms
  
• Santas thinks it is reasonable to think that the FOG accounts for the ideal aspects of every Form. That is, FOG explains any other Form's Form-ness (but not its proper attributes, namely what makes the Form of Piety piety or the Form of Equal equal)

P. 253