Ever since Hume wrote his Enquiry concerning Human Understanding in 1748, it has been recognized that induction can't be proved. Philosophers of science have long sought an objective basis for justification of scientific theories. This has been a difficult task, and it has not yet had a satisfactory solution.
In the "Duhem-Quine" thesis, these philosophers argued that falsification of a theory can be evaded indefinitely by adjusting the background knowledge in which the theory is embedded (Lakatos, Criticism and the Growth of Knowledge, 1970). However, we do not see this kind of behavior generally in science. On the contrary, among physical scientists it is common for "a beautiful theory to be brought down by one ugly fact" (Chris Quigg). There are examples throughout the history of science when new facts overwhelmed a closely-held theory. For example, Kepler believed that orbits of planets must be circular because the circle was the perfect figure, appropriate for heavenly bodies. But he was confronted with enough new, precise data from Tycho's observations of Mars that didn't fit a circular orbit. He eventually acquiesed in the face of the new data, and discovered that the orbits of planets are elliptical.
People, faced with new facts, sometimes change their minds -- in spite of "presuppositional" or "ideological" commitments to their present views. This can only happen if they believe -- or come to believe -- they are being confronted by objective truth. Note the inescapable paradox in this encounter.
"The world is real; it has an external existence entirely independent of my perceptions of it. This I believe with all my heart." (Leon Lederman).
"I believe that in spite of the hazards involved, I am called upon to search for the truth and state my findings." (M. Polanyi, Personal Knowledge, Ch. 10).
Polanyi based the credibility of personal knowledge on the shared commitments of a community (e.g. the scientific establishment). In the light of our limited knowledge as individuals, we must trust many of the rules and claims handed down to us. We share our knowledge in a community of committed persons. This view is lumped with Kuhn's and dismissed by Lakatos and others as "psychologism" or "social psychology", but unlike Kuhn, Polanyi recognized that there is only one objective truth to speak about; thus he denied relativism.
Personal knowledge is not mere subjectivity, much less solipsism. People routinely assume the general reliability of sense-data in order to function in practical life. A theist can go farther than this: sense-based knowledge of the world is generally reliable, because both the knower and object are given created status and placed in correspondence by the Creator (Sproul, Gerstner, Lindsley, Classical Apologetics; Francis Schaeffer, He is There and He is Not Silent). We are at home in the universe, not unknowing aliens locked in a "cocoon of consciousness".
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