Paradigm Shifts and Scientific Revolutions

• Discoveries in Section VI were causes or contributors to paradigm change
• Changes implicated by discoveries were destructive and constructive

Paradigm Shifts

• Assimilated discoveries enabled scientists to account for a wider range of natural phenomena, or with greater precision
• Gains were achieved by discarding standard beliefs/procedures, and replacing components of previous paradigm
• Shifts are associated with discoveries achieved through normal science, except for anticipated ones
• Discoveries are not the only source of destructive-constructive paradigm changes

Overlap of Discovery and Invention

• Sciences fact and theory, discovery and invention, are not categorically distinct

Emergence of New Theories

• Sorts of discoveries in Section VI were not singly responsible for paradigm shifts like Copernican, Newtonian, chemical, and Einsteinian revolutions
• Not even changes produced by wave theory of light, dynamical theory of heat, or Maxwell's electromagnetic theory
• Awareness of anomaly plays a role in the emergence of sorts of phenomena
• Profound awareness is prerequisite to all acceptable changes of theory

Historical Examples of Paradigm Shift

• Ptolemaic astronomy was a scandal before Copernicus' announcement
• Galileo's contributions to the study of motion depended on difficulties discovered in Aristotle's theory
• Newton's new theory of light and color originated in the discovery that none of the existing pre-paradigm theories would account for the length of spectrum
• The wave theory replaced Newton's, announced in the midst of growing concern about anomalies in the relation of diffraction and polarization effects to Newton's theory
• Thermodynamics was born from collision of two existing nineteenth-century physical theories, and quantum mechanics from difficulties surrounding black-body radiation, specific heats, and photoelectric effect
• The awareness of anomaly had lasted and penetrated so deep that one can appropriately describe the fields affected by it as a state of growing crisis

Crisis and New Theories

• The emergence of new theories is preceded by a period of pronounced professional insecurity
• Insecurity is generated by the persistent failure of the puzzles of normal science to come out as they should
• Failure of existing rules is the prelude to a search for new ones

Copernican Astronomy

• Ptolemaic system was successful in predicting the changing positions of both stars and planets
• No other ancient system had performed so well
• Ptolemaic astronomy is still widely used today as an engineering approximation for the stars and for the planets, Ptolemy's predictions were as good as Copernicus'
• Ptolemy's system never quite conformed with the best available observations, for both planetary position and precession of the equinoxes
• Further reduction of minor discrepancies constituted principal normal astronomical research problems for Ptolemy's successors

Problems with Ptolemaic System

• Astronomers could eliminate a discrepancy by a adjustment in Ptolemy's system
• Astronomy's complexity was increasing faster than its accuracy
• A discrepancy corrected in one place was likely to show up in another

Recognition of Crisis

• Awareness comes slowly, it was proclaimed that if God had consulted him when creating the universe, he would have received good advice
• Domenico da Novara, held that Ptolemaic system was too cumbersome and inaccurate to be true of nature
• Copernicus wrote that the astronomical tradition he inherited had created a monster
• By the early sixteenth century, an increasing number of Europe's best astronomers were recognizing that the astronomical paradigm was failing in application to its own traditional problems
• Recognition was prerequisite to Copernicus' rejection of the Ptolemaic paradigm and his search for a new one

The Oxygen Theory of Combustion

• Factors combined to generate the crisis preceding Lavoisier's oxygen theory of combustion in the 1770s

Rise of Pneumatic Chemistry

• The question of weight relations are of significance
• History begins in the seventeenth century with air pump development and its deployment in chemical experimentation
• Chemists realized that air must be an active ingredient in chemical reactions
• Chemists continued to believe that air was the only sort of gas
• Joseph Black showed that fixed air (CO2) was consistently distinguishable from normal air

Gas Investigation

• Cavendish, Priestley, and Scheele developed techniques capable of distinguishing one sample of gas from another
• Chemists believed in the phlogiston theory and employed it in their design and interpretation of experiments.
• Scheele first produced oxygen by an elaborate chain of experiments designed to dephlogisticate heat
• Experiments resulted in a variety of gas samples and gas properties so elaborate that the phlogiston theory was unable to cope with laboratory experience
• Chemists were unable to apply it consistently
• By the time Lavoisier began his experiments on airs in the early 1770's, there were versions of the phlogiston theory

Weight Gain in Combustion

• Lavoisier was concerned to explain the gain in weight that most bodies experience when burned or roasted
• Islamic chemists had known that some metals gain weight when roasted
• Roasted metal takes up some ingredient from the atmosphere
• Weight was not always taken to be the measure of quantity of matter
• Weight-gain on roasting remained an isolated phenomenon

Response to Weight Gain

• Responses to the problem of weight-gain became difficult
• Weight-gain accompanied roasting
• Assimilation of Newton's gravitational theory led chemists to insist that gain in weight must mean gain in quantity of matter
• Maybe phlogiston had negative weight, or fire particles entered the roasted body as phlogiston left it
• The problem of weight-gain led to an increasing number of special studies

Chemistry Crisis

• Phlogiston was considered as a substance with weight and weight changes it produces in bodies with which it unites
• Many different versions of the phlogiston theory were being elaborated to meet it
• Eighteen-century chemistry was gradually losing its unique status
• Research resembled that conducted under the competing schools of the pre-paradigm period

Physics in Crisis

• Late nineteenth century physics prepared the way for relativity theory
• Natural philosophers, notably Leibniz, criticized Newton's retention of absolute space
• Absolute positions and absolute motions were without function in Newton's system
• Aesthetic appeal a fully relativistic conception of space and motion would later come to display
• Critique was purely logical
• Transitions to a relativistic system could have observational consequences
• Views died with them during the early decades of the eighteenth century to be resurrected in the last decades of the nineteenth century

The Wave Theory of Light

• Accepted after about 1815, evoking no crisis until the 1890's
• Light is wave motion propagated in a mechanical ether governed by Newton's Laws
• Celestial observation and terrestrial experiment can detect drift through the ether
• Aberration promises to provide relevant information
• Detection of ether-drift by aberration measurements became a recognized problem for normal research

Attempts to Resolve the Problem

• Special equipment was built to resolve the problem. That equipment detected no observable drift
• Fresnel, Stokes, devised articulations of the ether theory designed to explain the failure to observe drift
• Each articulation assumed that a moving body drags some fraction of the ether with it
• Each was sufficiently successful to explain the negative results of celestial observation and of terrestrial experimentation, including the Michelson-Morley experiment

Max Well's Theory

• Maxwell believed that light and electromagnetism in general were due to variable displacements of the particles of a mechanical ether
• Maxwell's electromagnetic behavior of bodies in motion had made no reference to ether drag
• Attempts to detect motion with respect to the ether and to work ether drag into Maxwell's theory
• Series of observations to detect drift through the ether became anomalous
• Years after 1890 therefore witnessed a long series of attempts, both experimental and theoretical
• Analysists found its results were equivocal leading to a proliferation of competing theories
• Einstein's special theory of relativity emerged in 1905

Characteristics

• Novel theory emerges after a pronounced failure in normal problem-solving activity
• Breakdown and proliferation of theories is its sign
• Problems with respect to which breakdown occurred were recognized
• Novel theory seems a direct response to crisis
• Sense of failure, when it came, could be acute. Failure with a new sort of problem is disappointing but never surprising
• Solution to each of them had been at least partially anticipated during a period when there was no crisis in the corresponding science.

Anticipation

• Copernicus by Aristarchus in the third century B.C
• Geocentric system had no needs that a heliocentric system might have fulfilled
• The whole development of Ptolemaic astronomy falls in the centuries after Aristarchus' proposal.
• There were no obvious reasons for taking Aristarchus seriously
• Even Copernicus' proposal was neither simpler nor more accurate than Ptolemy's system
• The recognized crisis was responsible for innovation in the first place
• Ptolemaic astronomy had failed to solve its problems; time had come to give a competitor a chance
• Long neglect by scientists of Newton's relativistic critics must have been due to a similar failure in confrontation
• It is not even difficult to invent alternates
• Invention of alternates is what scientists seldom undertake except during the pre-paradigm stage of their science's development and at occasions during its subsequent evolution
• As in manufacture so in science-retooling is an extravagance to be reserved for the occasion that demands it
• The significance of crises is the indication occasions for retooling have arrived