What Is This Thing Called Science? / Alan Chalmers
Chapter 4: Deriving theories from facts
- - Scientific knowledge is constructed by first establishing the facts and subsequently building the theory to fit them à untenable
- - A logically valid deduction is if the premises are true, then the conclusion must be true
- - To assert the premises as true and to deny the conclusion = contradiction
- - An argument can be valid deduction even if it involves a false premise
- - Truth of factual statements that constitute the premises cannot be established by appeal to logic
- Can scientific laws be derived from the facts?
- - No it cannot if derive is interpreted as logically deduce
- - Universal statements refer to all events of a particular kind
- - But a number of true observations does not guarantee a true conclusion à not logical
- - Arguments which proceed from a finite number of specific facts to a general conclusion are inductive arguments, as distinct from logical, deductive arguments
- What constitutes a good inductive argument?
- - Not all generalizations from the observable facts are warranted
- - Conditions that must be satisfied to justify an inductive inference from observable facts to laws:
- 1. Large number of observations
- 2. Repetition under a wide variety of conditions
- 3. No accepted observation statement can conflict with the derived law
- - Principle of induction: if a large number of A have been observed under a wide variety of conditions and if all those A without exception possess the property B then all A have the property B
- - Condition 1: problem of arbitrariness of large number
- - Condition 2: problem what counts as a significant variation? – draw on prior knowledge
- - Condition 3: little knowledge would survive the demand that there can be NO exceptions
- Further problems with inductivism
- - Unobservable knowledge cannot be established by inductive reasoning
- - All observations are subject to some degree of error, yet many scientific laws take the form of exact mathematical formulas à how can exact laws ever be inductively justified on the basis of inexact evidence?
- - Hume: problem of induction arises for anyone who subscribes to the view that scientific knowledge in all its aspects must be justified either by an appeal to (deductive) logic (impossible) or by deriving it from experience
- - A general statement asserting the validity of the principle of induction is inferred from a number of instances of its successful application à inductive argument
- - One cannot justify induction by appealing to induction
- - The probability of the law in the light of the evidence is thus a finite number divided by infinity, which remains zero by whatever factor the finite amount of evidence is increased
- - Initial conditions: descriptions of experimental set-ups
- 1. Laws and theories
- 2. Initial conditions
- 3. Predictions and explanations
- - Observable facts are established by an unprejudiced use of the senses (no subjective opinion)
