SCIENTIFIC EXPLANATION Dr. Harry Firman harryfirman510@gmail.com Abstract This paper deals with several aspect about scientific explanation, including meaning, function, types, and structure of scientific explanation. Scientific explanation is contrasted with non-scientific explanation, particularly teleological and analogical explanations in their arguments. While, the two models of scientific explanation, which are deductivenomological (D-N) model and inductive statistical (I-S) then are contrasted in terms of their argument. Criteria for valid causality explanation is discuss at the end of this paper. Keywords: Science, explanation, D-N model, I-S model, covering law, causality. 1. Introduction Human curiosity for explanations of observed phenomena encourages the birth of the questions why it’s happened. Basicaly, explanation is a statement that shows a series of causes and effects that end in the phenomenon so that why a phenomenon occurs can be make sense answered. Superstition is often the basis for explanations of natural phenomena believed by ordinary people, such as irrationality when explaining the causes of some natural phenomena, like earthquakes, solar eclipses, mountain eruptions, plane crashes, rusting, disease outbreaks, etc. One of the functions of scientific knowledge is to provide a foundation for human efforts to explain scientifically to natural phenomena, both macroscopic and microscopic or even submicroscopic phenomena. It is not enough for scientific theories to describe the world as it is, they should also tell us why it is that way. With scientific explanations, 1 humans are detached from non-scientific explanations that are without scientific basis, and are often misleading, just as superstitious explanations are still rife in tradisional culture. Unlike superstisious explanations, scientific explanations use scientific theories and scientific laws as the basis. This paper discusses further the structure of the explanation, types of non-scientific explanation, and some scientific explanaton models. 2. Structure of Explanations Every explanation involves two essential elements, namely "explanans" and "explanandum". Explanans is the thing that explains, while explanandum is the thing that is explained (Ladyman, 2002). All explanations involve explanans and explanandum, but what distinguishes one type of explanation from another is the pattern of relationship between the two. There are two tipe explanations, namely non-scientific explanationand scientific explanation. Non-scientific explanations can take the form of "teleological explanations" and "analogical explanations". Whereas, scientific explanation includes two types of models, namely the “deductive-nomological model” (D-N Model) and the probabilitstic explanation model that it is called “inductive-statistical model” (I-S Model) (Mannoia, 1980). Each type of explanation model is detailed below. 2.1 Teleological Explanation The word "teleo" comes from the Greek word, meaning "destination". Teleological explanations answer the question of why about explanandum by taking the purpose as an explanans (Mannoia, 1980; Nasoetion, 1989), for example: 2 • Rain falls on the earth because all objects try to be at the center of the earth. • Humans have a heart because the heart functions to pump blood to all cells of the body. • Humans sweat so that body temperature is stable. • The egg has a yolk to provide food for the embryo to grow and develop. • The Na atom and the Cl atom bonding each other because they want to have an electron arrangement like the atom of noble gas which is stable. 2.2 Analogical Explanation Analogical explanation is an explanation that explains phenomena by comparing the phenomenon to better known or more concrete comparisons. The described phenomenon is called the "target", while the comparator is called the "analog". Analogical explanations answer the "how" question of explanandum, by referring to analogue explanans that are better known and more concrete. According to Mannoia, 1980) characteristics of analogical explanations include: (1) Explanandum is something complex and less well known; (2) Explanans are relatively better known; (3) Analogy is the relationship between explanandum and explanans, expressed by the word "like". Examples of analogical explanations are as follows. • The motion of electrons around the nucleus of an atom is like the motion of the planets around the sun in the solar system. • The role of catalysts in chemical reactions such as tunnel penetrate the hill so that increase the speed of chemical reactions. • Radio waves are explained by stating that they are ripple-like waves that form on the surface of pond water. 3 2.2 Scientific Explanation In scientific explanation, explanans is an empirical law or scientific theory. There are two models of scientific explanation: (1) Deductive Explanation (Hempel-Oppenheim Explanation Model); (2) Probabilistic Explanation (Ladyman, 2002). In the HempelOppenheim explanation model, an explanans is one or more general statements that are considered true, while the limiting statement limit the scope of the general statement's enforceability. The Hempel-Oppenheim model is also called the deductive-nomological model or "D-N model" for short. In Latin, scientific laws that general in nature are called nomos. Because it involves scientific law in formulating explanations, the D-N model is also called as the general law-based explanation model or “Covering Law Model of Explanation” (Rosenberg, 2005). The D-N explanatory model requires the following logical conditions: (1) The explanans must deductively lead to the explanandum, meaning that the explanandum must be derived deductively from the explanans; (2) Deduction should use common law; (3) The explanans must have empirical content (empirically tested) (Nasoetion, 199; Rosenberg, 2005). The explanation of the D-N model is illustrated in Fig. 1. 4 L1 , L2 , ……. Lx Explanans C1, C2, ……. Cx Explanation E Notes: L1, L2, ……. Lx C1, C2, ……. Cx Explanandum General theory or empirical laws Limiting statement With deduction principle, explanation is done to explanandum E This whole process is called Hempel-Oppenheim model of explanation 12 Fig 1. Illustration of D-N model of scientific explanation The followings are two sets of examples of D-N model, the first explain why the apple falls to the ground when unsupported. And the second explain why copper conducts electricity. Explanans (Covering Law): In accordance with Newton’ gravitational theory the Earth attracts all unsupported bodies. Explanan [Case] : That apple was unsupported body. Therefore, Explanandum : That apple fell to the Earth. Explanans [Covering Law]: In accordance with theory of metal bonding metals have structure that enables metals conduct an electric current. Explanant [Case] : Copper is a metal Therefore, Explanandum : Copper conducts electric current. 5 There are three aspects that cause problems in applying the D-N model, namely “irrelevance”, “over-determination”, and “symmetry”. Irrelevance problem occurs if part of the explanans is not a relevant fact, as in the following example: All metals conduct electricity Anything that conduct electricity is exposed to gravity Thus, all metals are exposed to gravity. The above argument uses the premise of the general law, but the fact that metals conduct electricity is irrelevant to metals being exposed to gravity. An explanation is said to be over-determination when more than one set of causal conditions are placed but they are all invalid, for example: People who take birth control pills will not get pregnant Jono [a man] took birth control pills Then, Jono will not get pregnant Judging from the D-N model, the above statement appears to be an explanation. But that's not really an explanation. Fact that Jono took birth control pills is not a valid part of the explanation that he will not get pregnant. An explanation is said to be symmetry if two events appear to "explain each other". Suppse it is an empirical law that all animals with hearts also have livers, and all animals with livers also have hearts, then it would be unsatisfactory to explain why a particular animal has a heart just because it has a liver, or vice versa 6 2.4 Probabilistic Explanation If statistical empirical laws are used to explain statistical events, explanations can still be called deductive explanations, as in the following example: The fact that 6 million smokers in America (in 1979) had lung cancer can be explained by the explanans consisting of the statistical law that "6% of American smokers have lung cancer," and that there are 100 million Americans as smokers. However, if statistical laws are used to describe particular events, explanation is not a deductive explanation, but an “Inductive-Statistical (I-S)” explanation because it is an inductive (statistical or probabilistic) argument based on statistical generalizations. For example, the phenomenon "soma has a heart attack" cannot be explained deductively from the explanation containing the statistical laws "90% of people with profession X have a heart attacks", and "Soma is in profession X". The explanation is inadequate for the explanandum, as shown in Fig. 2. Statistical Generalization 90% of the people in profession X have heart attacks Explanasn Soma in profession X ============================ 90% probable Soma had heart attack Explanandum Double lines mean probabilistic (inductive) explanatory arguments and has a 90% probability of coming true (by no means always will come true). I-S explanation usually accepted if the probability or higher > 50% Fig. 2. Illustration of I-S model of explanation 7 3. Explanation and Causality Causality is the explanation about relationship between one event (the cause) and the second event (the effect). In this context the second event is a result of the first event. For example, If X causes Y, then it is possible to explain and predict the effect Y based on the cause X, as well as take action to control the effect. The existence of causality is ensured by: (1) There is a constant association between cause and effect; (2) There is no effect if the cause is omitted; (3) Manipulation in cause results different levels of effect: (4) There is a theory that indicate the mechanism of cause-effect linkage. References Ladyman, J. (2002). Understanding philosophy of science. London: Routledge. Mannoia, V. J. (1986). What is science?: An introduction to the structure and methodology of science. Lenham, MD: University Press of America. Nasoetion, A. H. (1989). Pengantar ke filsafat sains (Introduction to philosophy of science). Bogor: Litera AntarNusa. Rosenberg. A. (2005). Philosophy of science: A contemporary introduction. New York: Routledge, 8