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This volume is a logical sequel of Volume I, The Search for System: indeed, it concerns the ways theoretical systems are put to work and subjected to test. Yet it can be read independently by anyone familiar with some factual theories, referring back to Volume I when necessary. Special Symbols AS;B the set A is included in the set B AvB the union of the sets A and B AnB the common part of the sets A and B aEB the individual a is in (or belongs to) the set A Card (A) cardinality (numerosity) of the set A AxB Cartesian product of the sets A and B en(A) consequence(s) of the set A of assumptions equals by definition =dt definition Dtú some x (or there is at least one x such that) (3 x) e empirical datum e translation of e into a semiempirical, semitheoreticallanguage h hypothesis m(r) measured value of the degree r m(;) average (or mean) value of a set of measured values of ,; P-jT T presupposes P p, q arbitrary (unspecified) propositions (statements) P(x) x has the property P (or x is a P) {xl P(x)} set of the x such that every x is a P pVq p and/or q (inclusive disjunction) p &q p and q (conjunction) p-+q if p, then q (conditional or implication) p if and only if q (biconditional or equivalence) p-q sum over i 2:; t theorem, testable consequence

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III Applying Scientific Ideas.- 9. Explanation.- 9.1. Answering Whys.- 9.2. Nonscientific Explanation.- 9.3. Scientific Subsumption.- 9.4. Interpretive Explanation.- 9.5. Interpretive Explanation and Reduction of Laws.- 9.6. Explanatory Power.- 9.7. Functions and Reach.- 10. Prediction.- 10.1. Projection.- 10.2. Stochastic Projection.- 10.3. Historical Projection.- 10.4. Projective Power.- 10.5. Riddles.- 11. Action.- 11.1. Truth and Action.- 11.2. Technological Rule.- 11.3. Technological Forecast.- IV Testing Scientific Ideas.- 12. Observation.- 12.1. Fact.- 12.2. Observability.- 12.3. Objectification.- 12.4. Data and Evidence.- 12.5. Function.- 13. Measurement.- 13.1. Numerical Quantification.- 13.2. Measured Value.- 13.3. Counting.- 13.4. Scale and Unit.- 13.5. Techniques.- 13.6. Upshot.- 14. Experiment.- 14.1. Planned Change.- 14.2. Control.- 14.3. Design.- 14.4. Significance.- 14.5. Testing the Test.- 14.6. Functions.- 15. Concluding.- 15.1. Inferring.- 15.2. Testing Observational Propositions.- 15.3. Testing Hypotheses.- 15.4. Confirmation and Refutation.- 15.5. A Case History: Torricelli.- 15.6. Testing Theories.- 15.7. Theory Assaying.- Author Index.

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