Good Example: "Why is biogenesis considered a basic assumption or theory and not a fact? An analogy will help to make this point clear. You may say, for instance, that it is a fact that a particular frog is made up of small microscopic units called cells, because you have examined this frog. You can only assume, however, that 'all frogs are composed of cells,' because that statement is a generalization based on limited observation. You might believe without any shadow of doubt that all frogs are made up of cells, but this still does not make your belief a fact." (Biological Science Molecules to Man, BSCS Blue, Teacher's Edition, Houghton Mifflin, 1968. p. 98)
Bad Example: "We know, for example, that humans evolved from common ancestors we share with other living primates such as chimpanzees and apes." (Biology, Miller & Levine, Prentice Hall, 1995, p. 757)
All scientific explanations are based on assumptions. It is only fair and intellectually honest to tell students what these assumptions are. For example, the most basic assumption underlying the explanation of macro-evolution by natural selection is metaphysical: nature is a permanently closed system of material causes and effects that can never be influenced by anything outside of itself.
Good Example: "A hypothesis usually consists of a group of interconnected statements, or assumptions, that give a possible solution to a problem. They are called assumptions because the scientist can only assume or suppose them to be true.... If a hypothesis has stood repeated testing over a long period of time and explains a wide range of facts, it may be called a theory." (Biological Science Molecules to Man, BSCS Blue Version, Teacher's Edition, Houghton Mifflin, 1968, pp. 14 & 15)
Good Example: "The next unit of this book is organized around the assumptions of the heterotroph hypothesis." (ibid. p. 102)
Bad Example: "Living things have evolved through modification of earlier life forms. That is, living things have descended from a common ancestor." (Prentice Hall Science - Evolution Change Over Time, Prentice Hall, 1993, p. 56 F)
Good Example: "The evolutionary history of animals indicates that there was an explosion of invertebrate diversification at the start of the Cambrian period." (Biology, Fourth Edition, Sylvia Mader, Wm. C. Brown Publishers, Times Mirror, 1993, p. 416)
Copyright ©1995 Norris
Anderson. All rights reserved. International copyright secured.
File Date: 12.22.95