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Cosmology has evolved from an essentially religious and mythical description of the supernaturalistic origins and nature of the universe to an essentially naturalistic description. These cosmological descriptions originated from man's attempt to answer several fundamental questions about the universe:
Ancient cosmologies and even cosmologies emerging through the age of enlightenment were closely intertwined with religious belief. Only within the last half-century or so has a specialized science of cosmology emerged without making explicit mention of God or deities. In these modern cosmologies immediate human concerns often appear to dwindle to insignificance in the scale of cosmic time and space. Before the twentieth century it often seemed that any serious non-mythical investigation of the ordered universe led to a Mover or a Designer who could be assimilated to the being whom men and women worshiped as God. Footnote1
The following are brief summaries of the major cosmologies influencing western thought. The progressive development toward modern scientific cosmologies can be detected in each subsequent cosmology.
Plato's Cosmology (428/427-348/347 B.C.) - Plato's account takes the form of a creation story, in the tradition of Greek mythologists. It is narrated by a philosopher named Timaeus of Locris (apparently a fictional character modeled on several of the Pre-Socratics). In this account, the whole of nature is initiated by a creator divinity, called the "Demiurge" (the Geek word for 'craftsman'), who seeks, to the best degree possible, to imitate through physical copies the ideally perfect structures of true being (i.e., the Ideas, or 'paradigms'). In this way he institutes the visible cosmos, that is, the ordered domain of things that are susceptible of process and change (e.g., birth, growth, alteration, and dissolution - the realm of 'becoming,' genesis). The Demiurge himself only assembles the supreme model of the cosmos, the 'world soul', and then delegates his divine subordinates to fit out the detailed structures of the parts of the cosmos. It follows that the whole cosmic system is pervaded with analogical structures, most notably, the human form, which becomes a copy of the whole - a microcosm, as it were - by virtue of the activity of these divine surrogates. All phenomena of nature can be described as an interplay between the two forces of reason and necessity. He represents reason as constituting the world soul. The material medium (four elements of earth, air, water and fire) is introduced as the 'receptacle' representing the domain of necessity. It is unclear whether Plato intended his cosmology as a literally true account of a created cosmos or a metaphysical fiction. Aristotle insisted that Plato must be held to his literal work, whereas Plato's immediate disciples favored a metaphorical reading. Division of opinion has continued to the present day.
Aristotle's Cosmology (384-322 B.C.) - Aristotle's cosmology was to dominate thought in the Western World for more than 2,000 years and its overthrow is arguably the major achievement of Renaissance science. Aristotle's views on the organization and structure of the universe are presented in De caelo. This work contains some of the basic considerations of motion. All locomotion is either straight, circular, or a combination of the two; and all bodies are either simple (i.e., composed of a single element, such as fire or earth) or are compounds. The element fire and bodies composed of it have a natural movement upward: bodies composed of earth have a natural movement downward (i.e., toward the center of the universe which is the earth). Circular movement is natural to some substances other than the four elements and the circular movement is considered more divine than these four elements (since circular motion is believed to be prior to straight movement). Aristotle views the universe as two-spheres where the changing region is up to the sphere of the moon, the earth is in the center surrounded by water, and air and fire are at the top, beyond which the heavenly bodies are in circular motion and in a realm without change. There is a separate set of physical laws for each of the two regions, since they are composed of different types of matter. Aristotle argues that the universe is not infinite because the universe moves in a circle (as we can see with our eyes if we watch the stars). If the universe were infinite, it would be moving though an infinite distance in a finite time, which is impossible. This is an argument employing the method of reductio ad absurdum (i.e., showing that the premise leads to an absurd conclusion thus proving the opposite premise must be true). Aristotle claimed also that there was only one world. He demonstrated this conclusion also using a reductio ad absurdum argument. If there were more than one world, each world with a center as the natural place for earthy material to move to and a circumference for fire to move to, then the earth could move toward any of the centers and fire toward any of the circumferences. Chaos would ensue. Since we observe order instead of chaos then there must be only one world. Aristotle also showed that the heavens rotate and that the earth is spherical, stationary and in the center of the heavenly sphere. In his arguments that the earth is spherical (based on the circular shadow during eclipse and that different stars are seen from different parts of the earth), Aristotle's use of observation is in stark contrast to Plato's rejection of the evidence of the senses. This is seen by some historians as a turning point in science, marking the beginning of extensive empirical investigations. However, Aristotle's cosmology has a number of teleological and animistic qualities that distinguish it from the modern mechanical explanations. While bringing to Greek science a new emphasis on the value of observation, Aristotle still differs in important ways from modern scientific practice. For example his observations are used more to persuade his readers of the truth of his conclusions than as an aid in arriving at his conclusions. Also Aristotle does not conduct critical experiments with which to test his conclusions.
Kant's Cosmology (1724-1804) - Kant provided the first model of a scientific, albeit highly speculative and qualitative, cosmology. His cosmology was thoroughly mechanistic and materialistic, but it makes clear that every cosmology must begin with the perception of a 'systematic constitution,' that could be viewed as evidence of some sort of 'grand design'. Although most of Kant's main tenets were mistaken, his work was of unprecedented scope, made detailed use of physical theory, and contained a number of fundamental insights. Kant's cosmological explanation takes the form of showing how the 'systematic constitution' arose, by way of Newton's laws of motion and the law of universal gravitation, from an original chaos. The chaos consists of atoms or particles of matter spread throughout an infinite space. According to Kant, the original chaos was unstable: the denser particles begin at once to attract the more tenuous. This is the explanation of the origin of motion and the formation of bodies, eventually of the planets. To prevent the universe from becoming one big massive ball Kant claims nature has still other forces in store which especially evidence themselves when 'matter is diluted into fine particles, whereby they repulse one another and through their conflict with [the force of] attraction produce that motion which is, so to speak, and enduring life of nature. Through this repulsive force, which reveals itself in the elasticity of vapors in the strongly smelling bodies and in the expansion of all spirituous matter and which is an indisputable phenomenon of nature, the elements sinking toward their points of attraction become directed side-wise in all sorts of ways and the perpendicular fall issues in circular motions which surround the center of sinking.' Lateral motion thus results when attractive and repulsive forces between any two bodies are equal and the one body, following the path of least resistance, begins to orbit about the other. As this summary indicates Kant's cosmology was largely qualitative. For example, he nowhere provides a law, similar to that for attraction, by which the force of repulsion can be determined. It is also important to note that while Kant's cosmology was naturalistic he never gave up the attempt to reconcile teleology and mechanism. In his Universal Natural History he claimed, that the very perfection of the mechanism in terms of which the development of the universe could be explained was at the same time the guarantee that it existed for a purpose and was not simply the product of accident and chance.
Modern Cosmology Footnote2 - Modern relativistic cosmology emerged in the 20th century. A science in a technical sense can emerge only after its philosophical foundations have been clearly and distinctly laid. Nevertheless, cosmology, like preceding scientific disciplines, seems to have developed its philosophical foundation by a largely unconscious process. The philosophical foundation of a science involves three essential stances; metaphysical, epistemological, and methodological. These are outlined in Table 1. We define what it means to be "scientific" as consisting of some choice of a combination of positions held within each categorical stance: Metaphysics + Epistemology + Methodology. Without this foundation we do not have a basis for stating 'what it is to be scientific'. The choice of the specific position under each categorical stance is independent of the specific position selected in the other categories. In other words the individual positions held within the metaphysical, epistemological, and methodological triad are mutually independent choices that are selected without reference to the position held in each of the other categorical stances.
Table 1. Philosophical Basis For What It Means to Be Scientific
| Metaphysical Stances This stance poses the question; "What sorts of entities, among those referred to by scientific statements, are to be understood as actual existents?" | Operationalism - Only those entities that can be simply and
directly observed are to be counted as real. The entities involved are those that may be
defined by some sort of operation with various physical instruments or equipment.
Explanatory Realism - This position adopts as an existence criterion something like "If a theoretical entity e must be hypothesized in order to explain observable phenomenon p, then e exists." |
| Epistemological Stances In this stance the question is asked; "What are the legitimate sources of scientific knowledge?" | Empiricism - Only information from observational and experimental
results are acceptable as a source for cosmological theorizing. Scientific knowledge is
founded in sensory observation. Rationalism - It is permissible for cosmologists to originate their theoretical efforts in very general ideas about what the universe should be like. |
| Methodological Stances The question related to this stance is; "What are the acceptable procedures for constructing a scientific theory?" | Hypothetico-deductivism (H-D'ism) - Hypotheses are generated on the
basis of general ideas about the universe, and then the consequences of these hypotheses
are deduced with the hope that at least some of the consequences involve observational
possibilities.
Inductivism - Logical induction is used to produce generalizations and extrapolations based on solid observational and experimental information. |
One of the relatively popular choices among several scientific fields is: Operationalism + Rationalism + H-D'ism. Another choice that has been identified is: Operationalism + Empiricism + Inductivism. Perhaps the most typical position of a physical scientist is: Realism + Empiricism + Inductivism. In the case of modern relativistic cosmology it was Operationalism + Rationalism + H-D'ism that ended up providing the philosophical model. The main point is that within science itself there are inconsistencies between what it means to be scientific from one discipline to the next. This is important because understanding the philosophical basis for a scientific interpretation of nature is an essential first step for a rational critique of the conflict between scientific cosmology and biblical cosmology.
Norriss S Hetherington (Editor), ENCYCLOPEDIA OF COSMOLOGY, Historical, Philosophical, and Scientific Foundations of Modern Cosmology, Garland Publishing, Inc., 1993.
Norriss S Hetherington (Editor), ENCYCLOPEDIA OF COSMOLOGY, Historical, Philosophical, and Scientific Foundations of Modern Cosmology, Garland Publishing, Inc., 1993.
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