[5.0.0] John Philoponus on Light

John Philoponus (490-570 AD) worked out an original theory of light:

  • According to Philoponus colour and light is subkind of energeia.
  • Light manifests directional.

The following OntoUML diagram presents the theory of light

Philoponus on Light

CLASSDESCRIPTIONRELATIONS
Energeia“light it has been said that Philoponus ‘completely rejects’ Aristotle, turning light from a static to a kinetic phenomenon better suited to the needs of geometrical optics, and changing the meaning of Aristotle’s word energeia in the process.
It is an important contribution to have drawn attention to Aristotle’s innovation here, but I am not sure that the innovation has been rightly understood.
We need to distinguish light from the action of colour. Each can be called an energeia. Light is the state in virtue of which a transparent medium can actually be seen through, whereas in the dark the medium is only potentially seeable-through. This is what Aristotle means, as Philoponus sees, when he calls light the actualised state (energeia, entelecheia) of the transparent.”
Colour“There is also an energeia of colour. Philoponus uses the for something that goes on in the medium between the observer agrees that colour acts on the medium, but he prefers to rather than an energeia (activity).
To his kinesis he applies De generatione animalium speaks of the kinesis as ‘arriving’, distant object, and as ‘taking a straight course’ or ‘being scattered’. “
subkind of
LightLight is the state in virtue of which a transparent medium can actually be seen through, whereas in the dark the medium is only potentially seeable-through. This is what Aristotle means, as Philoponus sees, when he calls light the actualised state (energeia, entelecheia) of the transparent.”
Whatever may be the case about colour, it is made emphatically light does not travel in the sense of affecting one part of Light should rather be thought of as a state in virtue of actually seeable-through…”
subkind of
DirectionalWhat I conclude is that Philoponus does indeed change Aristotle’s theory of light to make it directional in the way it needs to be. On the other hand, he does not introduce travel in the sense of a time-taking process. Nor does he overthrow
Aristotle’s theory of the action of colour on the medium. Instead, he gives to light the same directionality as was already to be found in Aristotle’s account of the action of colour.

Sources

  • SORABJI, RICHARD: “HILOPONUS AND THE REJECTION OF ARISTOTELIAN SCIENCE”, EDITED BY RICHARD SORABJI INSTITUTE OF CLASSICAL STUDIES SCHOOL OF ADVANCED STUDY UNIVERSITY OF LONDON 2010
  • Wildberg, Christian, “John Philoponus”The Stanford Encyclopedia of Philosophy (Winter 2021 Edition, Edward N. Zalta (ed.)

First published: 16/5/2022

 

[4.20] Marsilius of Padua on the Role the of Supreme Ruler

Marsilius of Padua (1243? – 1316) in the work Defensor pacis (1324) rejected the doctrine of absolute papal power of Boniface VIII. sustained by Giles of Rome. He thinks that:

  • There is one and only one supreme ruler who holds all coercive power in a community.
  • “The supreme ruler cannot be a cleric, since Christ has forbidden the clergy to become involved in temporal affairs (113–40/159–92). And the supreme ruler does not enforce divine law as such, since God wills that divine law should be enforced by sanctions only in the next world, to give every opportunity for repentance before death (164, 175–9/221, 235–9).”
  • Clerics, members of the general council, and the Pope all have doctrinal authority.
  • All people have the right to ownership and property except Clerics.
  • Coercive power, doctrinal authority, and property are subkinds of power.

See also Giles of Rome on Papal Power.

The following OntoUML diagram explains the view Marsilius of Padua power:

Marsilius on power
ClassDescriptionRelations
ChurchThe church has members.
PersonA human personmember of Church; has Powe
SupremeRuler“He argues that all coercive power comes from the people (44–9, 61–3/65–72, 88–90), and that no people can have more than one supreme ruler, who is the source of all coercive power in that community (80–6/114–22). The supreme ruler cannot be a cleric, since Christ has forbidden the clergy to become involved in temporal affairs (113–40/159–92). And the supreme ruler does not enforce divine law as such, since God wills that divine law should be enforced by sanctions only in the next world, to give every opportunity for repentance before death (164, 175–9/221, 235–9). The supreme ruler is therefore not an enforcer of religion and his rule is not subject to direction by the clergy.”role of Person
Cleric“the pope has from Christ no more authority than any other clericrole of Person
GeneralCouncilMemberMarsilius did believe that the Church exercised some authority over its members, but, so far as this was a doctrinal authority, it was exercised not by the pope but by a general council member (Marsilius held that the Bible and general councils are infallible, but not the pope (274–9/360–66)).”role of General Council Member
Pope“Within the Church, the Pope has from Christ no more authority than any other cleric. Christ did not appoint Peter as head of the Church, Peter never went to Rome, the bishop of Rome is not Peter’s successor as head of the Church (pp. 44–9/61–3)”role of Pope
CoercivePower“He argues that all coercive power comes from the people (44–9, 61–3/65–72, 88–90), and that no people can have more than one supreme ruler, who is the source of all coercive power in that community (80–6/114–22).” subkind of Power
DoctrinalAuthority“Marsilius did believe that the Church exercised some authority over its members, but, so far as this was a doctrinal authority, it was exercised not by the pope but by a general council (Marsilius held that the Bible and general councils are infallible, but not the pope (274–9/360–66)). Now that Europe is Christian a general council cannot be convened or its decisions enforced except by the Christian lay ruler (287–98/376–90).” subkind of Power
PropertyAll people have the right to ownership and property except Clerics.
“As for religious poverty, Marsilius sides with the Franciscans and takes their doctrine further: not only is it legitimate for religious to live entirely without ownership of property (they can use what they need with the owner’s permission), but this is what Christ intended for all the clergy (183–4, 196–215/244–6, 262–86). Thus on his view the pope and clergy should have no lordship at all, either in the sense of coercive jurisdiction or in the sense of ownership of property. His position is diametrically opposite that of Giles of Rome.”
subkind of Power
PowerPower

Sources

  • All citations from: Kilcullen, John and Jonathan Robinson, “Medieval Political Philosophy“, The Stanford Encyclopedia of Philosophy (Winter 2019 Edition), Edward N. Zalta (ed.)

First published: 4/4/2022