[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

 

[4.15.8] John Duns Scotus on Contingency of the Present and Free Will

John Duns Scotus (the “Subtle Doctor,” 1265/66–1308 AD), in “Quaestiones super libros Metaphysicorum Aristotelis”, “Lectura” and “Ordinatio” writes about modal theory, contingency of the present, and free will. His main ideas are:

  • He thinks, that modality (necessity and contingency) is not essentially connected to time.
  • The past is necessary, but contrary to the Aristotelian view (see [1.3.19]), the present is contingent, as the future is.
  • The present is contingent because, at a given time, we can have alternative open possibilities (potencies), all with the capacity to realize (actualize) in the instant of the present moment. In these cases, the present event is not necessarry because all the alternative possibilities could realize in the present instant. In these cases we don’t have an ordering in time of the potency and the actualized potency, but an ordering of instants of nature.
  • As a self-mover, the free will of the intelligent creature can pick one (or more) of the alternative possibilities and realize it in the present instant.

The following OntoUML diagram presents Duns Scotus’s theory of contingency of the present and free will.

Scotus on contingency of the present and free will
ClassDescriptionRelations
Time“In his Physics Aristotle defines time as the measure of change (kinesis) with respect to prior and posterior and defines change as the actualization of a potentiality as such.”
PastScotus accepts the necessity of the past.
“the past and future met in the present instant”
phase of Time
Present“He denies the same necessity to the present. […]
The present instant can, at a minimum, be regarded as a pair of instants of nature ordered as before and after in nature. […]
Scotus thinks that it is because of this ordering of nature within the present instant of time that we can speak of the present as being only contingently the way it is. It is as if the past and future met in the present instant with the prior instant of nature belonging to the past (as its endpoint) and the posterior one to the future (as its beginning).”
phase of Time
Future“the past and future met in the present instant”phase of Time
PotencyPotency in the Aristotelian sense (see [1.3.4]).
Example: “Consider a rational creature – an angel, for example – that exists only for an instant during which it is, let us suppose, loving God. The question posed is whether it could be loving God freely. The argument that the angel could not be loving God freely is that for it to do so it has to have a power [potency] to do otherwise, say, to hate God.”
prior to ActualizedPotency; is in Present
Not-actualizedPotencyNot-actualized potency, in the Aristotelian sense (see [1.3.4]) : a potency, which has not been realized.
Example: The angel does not hate God.
role of Potency
ActualizedPotencyActualized potency, in the Aristotelian sense (see [1.3.4]) : a potency, which has been realized.
Example: The angel loves God.
role of Potency; is in Present
OrderingOfInstants
OfNature
“not all causal relations (largely understood) involve succession in time. For Scotus the productive relations within the Trinity serve as obvious cases in which no temporal succession is involved, and the creation of the world (and with it motion and so time) is another. Even in natural philosophy the picture of light’s being propagated instantaneously through a diaphanous medium by the sun, a hypothesis certainly compatible with the empirical data available to Scotus, served as a case of a causal process in which the effect and the cause were coincident in time and in which, despite the temporal coincidence, there is a clear sense in which emission of light by the sun is prior to its reception on the earth. Now if one holds, as Scotus did, that in the relevant sense a power [potency] must be prior to its actualization (see In Metaph. 9, q. 14, for example) and one accepts the Propositio Famosa, one could generalize these examples to produce a partial ordering of instants of nature. A is naturally prior to B if and only if mention of A is required in giving an explanation of B. We can now give a sufficient condition for the distinctness of two instants of nature n1 and n2. […]”
Example: “In the context of the angel existing only for a single temporal instant, Scotus treats an instant of time as divisible into a sequence of instants of nature. […] The prior is that in which the angel has both the power [potency] to love God and the power to hate God, and the posterior is that in which the angel has actualized the power [potency] to love God. These are prior and posterior in nature because the power [potency] to love God is naturally prior to its actualization. Since ‘in’ the instant of time there is an instant of nature (namely the prior of the two) at which the angel has the power to hate God, we can say that the angel has the power [potency] to hate God at that instant of time (and could, relative to that ‘prior’ instant of nature, actualize it at the posterior instant of nature), and thus the angel is now free. [his will is free]”
relates Potency with ActualizedPotency
Creature’sWillCreature’s will “is the exercise of a rational power – that is, a power for opposites – that includes the ‘nonevident’ power for the contrary at time t of whatever it is actually choosing at time t.”
Example: “the angel could not be loving God freely is that for it to do so it has to have a power [power] to do otherwise, say, to hate God.”
recognizes Potency; decides for ActualizedPotency; is in Present
DecisionDecision of the Creature’sWill about the Potency to actualize. Relates Creature’sWill with ActualizedPotency
SelfMoverA creature’s (e.g. a human or an angel) will is a self mover, because it has “a power for opposites – that includes the ‘nonevident’ power for the contrary at time t of whatever it is actually choosing at time t.”
Example: The angel could love or hate God.
characterizes Creature’sWill

Sources

  • All citations from: Normore, Calvin G., “Duns Scotus’s Modal Theory”, The Cambridge Companion to Duns Scotus, Cambridge University Press 2003, ed. Thomas Williams
  • Williams, Thomas, “John Duns Scotus“, The Stanford Encyclopedia of Philosophy (Winter 2019 Edition), Edward N. Zalta (ed.)

First published: 20/5/2021