Mediocrity principle
From Wikipedia, the free encyclopedia
 |
This section does not cite any references or sources. (June 2007) Please help improve this section by adding citations to reliable sources. Unverifiable material may be challenged and removed. |
The mediocrity principle is the notion in the philosophy of science that there is nothing special about humans or the Earth. It is a Copernican principle, used either as a heuristic about Earth's position or a philosophical statement about the place of humanity. The mediocrity principle is further boosted by:
- Fossil evidence supported by genetics concluding that all humans have a common ancestor about 100,000 years ago and that they share a common ancestor with chimpanzees about six million years ago. Therefore humans are part of the biosphere, not above it or unique to it.
- Humans share about 98% of their DNA with chimpanzees. Chimpanzees have actually undergone more genetic change than humans[1].
- The answering of Schrödinger's question What is Life? through the discovery of the double-helix structure of DNA and the reduction of life to organic chemistry, negating the vitalism of previous centuries.
- Edwin Hubble discovered that the universe is substantially larger than humans first thought and James Hutton discovered the Earth is a lot older. The Hubble Deep Field is a long exposure of thousands of galaxies, making it one of the best pictorial representations of the principle of mediocrity.
- The Pale Blue Dot photograph was taken by Voyager 1 on February 14, 1990. It shows Earth from over 4 billion miles (6.4 billion kilometers) away, the farthest distance Earth has been photographed from.
Contents |
[edit] Earth is an unexceptional planet
|
|
This section does not cite any references or sources. (June 2007) Please help improve this section by adding citations to reliable sources. Unverifiable material may be challenged and removed. |
The traditional formulation of the Copernican mediocrity principle is usually played out in the following way: Ancients of the Middle East and west once thought that the Earth was at the center of the universe, but Copernicus proposed that the Sun was at the center. This heliocentric view was confirmed a hundred years later by Galileo, who demonstrated with a telescope that Jupiter's moons orbited Jupiter and that Venus must orbit the Sun. In the 1930s, RJ Trumpler found that the solar system was not at the center of the Milky Way Galaxy (as Jacobus Kapteyn claimed), but 56% of the way out to the rim of the galaxy's core. In the mid-twentieth century, George Gamow (et al.) showed that although it appears that our Galaxy is at the center of an expanding universe (in accordance with Hubble's law), every point in space experiences the same phenomenon. And, at the end of the twentieth century, Geoff Marcy and colleagues discovered that extrasolar planets are quite common, putting to rest the idea that the Sun is unusual in having planets. In short, Copernican mediocrity is a series of astronomical findings that the Earth is a relatively ordinary planet orbiting a relatively ordinary star in a relatively ordinary galaxy which is one of countless others in a giant universe, possibly within an infinite multiverse.
[edit] Critics of the 'ordinary earth' mediocrity principle
 |
This article or section includes a list of references or external links, but its sources remain unclear because it lacks in-text citations. You can improve this article by introducing more precise citations. |
In arguing that our planet, and human evolution, civilization, and technology are unexceptional, SETI advocates invoke the mediocrity principle as a strong reason (via prior probability) to expect abundant extraterrestrial signals. For instance, Carl Sagan used the principle to argue that "there might be one million civilizations in the Milky Way.” The failure to find such signals or evidence is taken by some as a refutation of the mediocrity principle: the lack of contact is interpreted more often as a scarcity of human-like intelligence than a scarcity of Earth-like planets, but a scarcity of either could be construed as a refutation of the mediocrity principle, depending on whether the principle is applied strictly to the planet or, more loosely, to its inhabitants. However, there may be a relative abundance of both sapient beings and Earth-like extra-solar planets but the distance between us and instances of either may be too great to allow for detection.
The antithesis of the mediocity principle for Earth is the Rare Earth hypothesis; for example, Gonzalez and Richards (2004) present the case for Earth's uniqueness, in their book The Privileged Planet. Supporters of the Rare Earth hypothesis claim:
Not that we are at the 'center' of the universe, but rather at the best location for complex life to flourish and to observe what is beyond us.
—[1]
Supporters of the Rare Earth hypothesis argue that not only is the cosmos as a whole finely tuned for life, but within it, the Earth's peculiarities make it an extremely special 'Pale Blue Dot'. Rare Earth: Why Complex Life is Uncommon in the Universe, written by Peter Ward, made similar claims in 2000. These objections to the mediocrity principle are based on the hypothesis that the following planetary advantages are both extremely uncommon and absolutely essential for life:
- Earth is the right orbital distance from a non-binary, metal-rich star (the Sun) with stable radiation over an ideal frequency spectrum. If the Sun were larger, it would burn too quickly for life to evolve and if it were smaller, the Earth would need to be closer, making it tidally locked.
- Earth has a nearly circular orbit. This condition is not rare in our solar system, possibly due to Jupiter's gravitational influence, but observations of exosolar planets suggest that it is rare elsewhere.
- Earth is a silicate rock with the prerequisite mass, plate tectonics, and iron core to protect developing life from radiation.
- Jupiter and the other large outer planets may shield the Earth from asteroids without destabilizing its orbit as well as shuttling water-rich comets from the outer solar system to the inner.
- Earth has the perfect amount of water for a long-term active hydrosphere.
- The Moon is anomalously massive, creating large oceanic tides, and stabilizing the Earth's axial tilt. According to Jacques Laskar's calculations this critical feature is otherwise impossible to achieve.
- The manner in which the Moon was created, by collision of a mars-sized body with Earth, may have stripped the Earth of some of its crust material. This deficit of crust material allows plate tectonics. Without plate tectonics the Earth might undergo essentially complete volcanic resurfacing as Venus does.
- The Earth's location within the galaxy is rare and important: "Not in the center of the galaxy, not in a globular cluster, not near an active gamma ray source, not in a multiple-star system, or near a pulsar, or near stars too small, too large, or soon to go supernova." (Rare Earth page 282).
- Earth's orbital and temperature stability over billions of years is exceedingly rare, as is its insulation from cataclysmic events.
[edit] On the ordinariness of humanity
- When the Human Genome Project released its findings in 2003, it was discovered that the human genome only has 24,000 genes. As recently as the 1990s, humans were considered so complex as to have about 300,000 genes.
- Evolutionary psychology is discovering the limits to human rationality, biological psychology exposes the material nature of cognition and moral sense with fMRI scans, economic and political studies find regularities in the behaviors of large groups of humans.
- Francis Crick's "Astonishing Hypothesis" is that consciousness is simply the function of the brain.
[edit] As a philosophical statement
 |
This article or section is missing citations or needs footnotes. Using inline citations helps guard against copyright violations and factual inaccuracies. (June 2007) |
|
|
This section needs additional citations for verification. Please help improve this article by adding reliable references. Unsourced material may be challenged and removed. (June 2007) |
There is a stronger, philosophical version of the mediocrity principle. This associates the Renaissance with greater openness to radical ideas. The belief is that the Roman Catholic dogma of the day, with regards to the place of Earth in the cosmos, was that if God made man in God's image and that this were God's most perfect creation, then there was only one logical place to put this most perfect creation—at the center of the Universe. Therefore, Copernicus's suggestion that Earth was not the center of the entire Universe, implied the theological conclusion that man was not God's most perfect creation. Although this is a popular interpretation of history and of man's position in the cosmos, it is not historically accurate. Medieval theologians, most vividly illustrated in Dante's Divine Comedy, viewed the heavens as perfect, and Earth (and humans) as the dregs (rather than the pinnacle) of creation. Thus it seemed that Copernicus was actually promoting rather than demoting the Earth by removing it from the "basement", and the paradigm shift was of a very different character.
[edit] See also
- The Rare Earth hypothesis is the antithesis of the Mediocrity principle
- Anthropic principle - the only universe that we can observe is one that allows for our existence.
- Cosmic pluralism
- Geocentric cosmology of Aristotle and Ptolemy
- Ptolemaic system
- Plenitude principle
- Uniformity principle
- Drake equation
- Total Perspective Vortex
- Deep ecology
[edit] References
[edit] Notations
- Gonzalez, Richards, The Privileged Planet: How Our Place in the Cosmos is Designed for Discovery 2004, Regnery Publishing, ISBN 0-89526-065-4
- Peter Ward and Donald Brownlee. Rare Earth: Why Complex Life is Uncommon in the Universe. Copernicus Books. January 2000. ISBN 0-387-98701-0
[edit] Footnotes
[edit] External links
- Goodwin, Gribbin, and Hendry's 1997 Hubble Parameter measurement relying on the mediocrity principle The authors call this the 'Principle of Terrestrial Mediocrity' even though the assumption they make is that the Milky Way Galaxy is typical (rather than Earth). This term was coined by Alexander Vilenkin (1995)
