Cosmic pluralism, the plurality of worlds, or simply pluralism, describes the philosophical belief in numerous “worlds” in addition to Earth (possibly an infinite number), which may harbour extraterrestrial life.  

(from Wikipedia article “Cosmic Pluralism“)

In my criticism of Adamson’s initial argument for the existence of God, I pointed out that cosmic pluralism is an idea that has been around since the beginning of Western philosophy about 2,500 years ago (the pre-socratic philosopher Anaxagorus advocated cosmic pluralism, for example), and that cosmic pluralism was advocated in Europe more recently by Giordano Bruno, about 430 years ago. Furthermore, cosmic pluralism was a view held by many of the leading philosophers that are usually covered in introductions to philosophy and in history of philosophy courses: Gottfried Leibniz, Rene Descartes, George Berkeley, John Locke, and Immanuel Kant. Some of the founding fathers of our nation were cosmic pluralists: Thomas Paine, John Adams, Benjamin Franklin, and probably Thomas Jefferson too.

I previously pointed out that science fiction books, stories, movies, and television programs often assume the truth of cosmic pluralism, so even if Adamson was completely ignorant of the history of philosophy and ignorant about the cosmological beliefs of our founding fathers, she ought to have been aware of the idea of cosmic pluralism from science fiction books or movies or television shows.

One might object that cosmic pluralism is a matter of speculation.  Anaxagorus was not a scientist, at least not in the modern sense.  He did not use a telescope to observe the planets in our solar system or the stars in our galaxy.  Bruno was not a scientist; he was a philosopher and theologian.  Bruno arrived at his theory of the universe based on abstract philosophical and theological reasoning, not on the basis of empirical science, not on the basis of careful observations and measurements, not on the basis of experiments.  Science-fiction stories and movies might well assume the truth of cosmic pluralism, but that doesn’t mean that we ought to believe that cosmic pluralism is true; fiction can be based on false or unproven assumptions.

In the previous post in this series I pointed out that Bruno may have been influenced to adopt cosmic pluralism and the view that the universe was infinite by the English mathematician and astronomer Thomas Digges.  Furthermore, Bruno was burned at the stake (by the brilliant Christian leaders of the Roman Inquisition) in 1600, and just ten years later Galileo published the first scientific work of astronomy based on observations made with a telescope: Sidereal Messenger (or Sidereal Message).  In that publication, Galileo reported that he was able to see many more stars with his telescope than what others had been able to observe with the naked eye. In 1750, the English astronomer and mathematician Thomas Wright published a book which suggested that observed faint nebulae indicate that the universe includes far distant galaxies.  By the end of the 19th century, astronomers were able to observe about 125 million stars using the telescopes available at that time. In 1920, there was the “Great Debate” in astronomy over whether the universe includes far distant galaxies beyond our own galaxy (as Thomas Wright had proposed back in 1750). In that debate the astronomer Heber Curtis argued that Andromeda and other  nebulae were separate galaxies. In 1925, the astronomer Edwin Hubble presented a scientific paper that provided powerful evidence supporting Curtis’ view that the universe included far distant galaxies.

So, we see that from the time of Giordano Bruno through the 1920’s scientific investigation of the universe has provided more and more evidence supporting cosmic pluralism. However, until fairly recently, we had no scientific proof that there were other planets in the universe outside of our own solar system.  Although astronomers and other scientists have long supposed that there were other planets in other solar systems (called “exoplanets”), scientific proof of this did not exist until near the end of the 20th century:

For centuries philosophers and scientists supposed that extrasolar planets existed, but there was no way of detecting them or of knowing their frequency or how similar they might be to the planets of the Solar System. Various detection claims made in the nineteenth century were rejected by astronomers. The first confirmed detection came in 1992, with the discovery of several terrestrial-mass planets orbiting the pulsar PSR B1257+12. The first confirmation of an exoplanet orbiting a main-sequence star was made in 1995, when a giant planet was found in a four-day orbit around the nearby star 51 Pegasi. Some exoplanets have been imaged directly by telescopes, but the vast majority have been detected through indirect methods such as the transit method and the radial-velocity method.  (from the Wikipedia article Exoplanet)

Many planets and planetary systems have been discovered in recent decades:

Over 3000 exoplanets have been discovered since 1988 (more specifically, 3412 planets in 2554 planetary systems, including 578 multiple planetary systems, have been confirmed, as of 23 May 2016).    (from the Wikipedia article Exoplanet)

So, we now know that Giordano Bruno’s view of the the universe was largely correct.  There are at least 100 billion planets in our galaxy, the Milky Way galaxy, and there might well be about 10 trillion planets in our galaxy.  If we use the lower estimate and assume this to be an average number for a galaxy, then the approximate number of planets in the observable universe is about the same as the number of stars:

200,000,000,000 galaxies  x  100,000,000,000 planets/galaxy =

 20,000,000,000,000,000,000,000 planets

Most of those planets are not hospitable places for plants and animals and humans, but even if only one-in-a-million planets was suitable for living creatures, that would mean that about this many planets would be suitable for life:

 20,000,000,000,000,000 planets

If there are anywhere near this number of planets that have conditions suitable for sustaining living creatures, then it is virtually certain that there are other planets in other solar systems in the universe that have living plants and animals on them, and it is highly probable that among those other planets in other solar systems that have living plants and animals, there are some intelligent animals that have developed language, mathematics, and knowledge about natural phenomena.  In other words, scientific investigation of the universe has shown that it is highly probable that cosmic pluralism is correct.

Giordano Bruno should not have been burned at the stake.  If anyone deserved to be burned at the stake, it was the shit-for-brains Christian leaders of the Roman Inquisition who should have been barbequed.  My thanks to Adamson for reminding us of the history of ignorant, dogmatic, and brutally oppressive Christian leaders in Europe by her failure to make any mention of Giordano Bruno or of cosmic pluralism, which constitute an obvious objection to her pathetic and intellectually worthless initial arguments for the existence of God.