A planet, or a satellite?

ESO/M Kornmesser

On July 23, the journal Nature published an article announcing the discovery of what it called an “exosatellite,” although in my opinion, this is a wordplay with the meaning of the word satellite. Let's look at the concepts involved:

·         In our solar system, there is a central star, the Sun, around which eight planets, several smaller planets, and many thousands of asteroids and comets revolve. In addition, almost all the planets have satellites, much smaller than the planets. The largest in proportion to its planet is the Moon, whose mass is 81 times less than that of Earth. There are four satellites larger than the Moon: three of Jupiter (Ganymede, Callisto, and Io) and one of Saturn (Titan). Many exoplanets have been discovered in systems of this type.

Ontological proof of God’s existence

Elizabeth Anscombe 

In 1078, Saint Anselm of Canterbury proposed a proof of God’s existence in his work Proslogion, which has given rise to various versions that attempted to improve it (usually without success) and to attempts to demolish it. Even today, it continues to provoke the attention of philosophers and corrections to its translation. This is Saint Anselm's argument, originally written in Latin, as it is usually translated:

i.      That than which nothing greater can be conceived at any rate exists in the mind of the fool who says there is no such thing.

ii.   If that than which nothing greater can be conceived is only in a mind, it can be thought to exist in reality too, which is greater.

iii. Therefore if that than which nothing greater can be conceived is only in a mind, it is not that than which nothing greater can be conceived.

iv.  But it is a contradiction to say that something than which nothing greater can be conceived is something than which a greater can be conceived.

v.    Therefore that than which nothing greater can be conceived exists in reality as well as in the mind.

The Origin of the Universe and the Immortality of the Soul

Aristotle

The philosophical and scientific works of Aristotle were lost to Western Europe for centuries and were rediscovered through Arabic translations. Their rediscovery gave rise to a Western European philosophical movement, Scholasticism, with such prominent figures as Albertus Magnus, Thomas Aquinas, Duns Scotus, William of Ockham, Jean Buridan, Albert of Saxony, Nicholas Oresme, Gregory of Rimini, and many others.

I will recall here a curious debate that took place among the Scholastics between the 12th and 14th centuries, which may seem pointless to us today, but which was quite important in its time. For those who wish to learn all the details of the debate, I recommend Pierre Duhem's book, Le Système du Monde, volume VII.

The debate originated from the detection of an incompatibility between two statements due to Aristotle: