Paradigms, Revolutions, Changes in World View

J. Blackmon

Contents• Phlogiston• Normal Science• Crisis and Revolution• Incommensurability

PhlogistonA Theory of Combustion (as presented by Edwin Hung)• Hypothesis: Phlogiston is a substance which resides in

combustible things, making them combustible, and it is given up during combustion.• Hung writes that Becher and Stahl were working

within a paradigm reaching back to Aristotle, that simple elementalism we studied earlier.

PhlogistonObservation Explanationcharcoal when burnt turns to ashes, water vapor, fire

Made of earth, water, lots of phlogiston

candles, wood EWPPP E+W+PPP (Modern chemistry: carbon combines with o2 yielding co2)

fire in a confined space won’t last Space becomes “saturated” w phlogiston. Air becomes “fixed”. (O2 exhausted)

metallic ore mixed with charcoal and heated, it burns and produces other metals

Phlogiston is released and attaches to oreMetal is E+PLook, it’s shiny and bright, and sulfuric acid brings it back out.EE (ore) + EWPPP (charcoal) EEPP+E+W+P (metal, ash, water vapor, phlogiston)

calcination (rusting) rusting iron turns to reddish brown dust

slow burning E left behind EEPP(metal) EE(rust)+PP(phlogiston) 

PhlogistonAn Anomaly: Some burned objects gain weight. • For example, magnesium –Mikhail Lomonosov

PhlogistonAn Anomaly: Some burned objects gain weight.• But here’s what people asked: Why would a thing gain

weight when something leaves it?• Maybe phlogiston is lighter than air, making things buoyant.• Maybe phlogiston has negative weight! (Levity, instead of

gravity?)

• Kuhn holds that such research was conducted from within a paradigm, and paradigm determine our data.• The paradigm, which encompasses more than just a

theory, frames the way we understand what we observe.

PhlogistonAn Anomaly: Some burned objects gain weight.• Lavoisier (1743-1794): Maybe something goes into it.• And we were on the road to the discovery of oxygen.

• Paradigms determine out data. Our observations are “theory laden”.• Psychology had recently been uncovering just how

susceptible we are to illusions and cognitive bias.

PhlogistonParadigms• Broad Sense: A package of ideas and methods that

make up a view of the world and a way of doing science.• Narrow Sense: A particular achievement or exemplar

in science.• Mendel’s pea experiments• Newtonian Mechanics• Maxwell’s Laws for Electromagnetism• Einstein’s Theories of Relativity (special and general)

Normal ScienceMost scientific work is conducted within a period of normal science.• Paradigms (narrow) inspire future work, supply a

model. A tradition grows up, and scientific behavior becomes organized, even rigidified. We have an absence of debate about the fundamentals.• This contrasts with Popper’s view according to which

all conjectures, even the fundamentals, are continually open to critical tests. • Kuhn holds that during the period of normal science,

much of what goes on is not attempts to falsify, but attempts to solve puzzles.

Normal ScienceMost scientific work is conducted within a period of normal science.• Puzzle-solvers try to align theory and observation in

accordance with a paradigm, and it is the paradigm which helps identify the puzzles and the goals of puzzle-solving.

Normal ScienceKuhn’s View vs. Falsificationism• Maybe alleged falsifiers should be (as they often are)

more often considered as being due to faults of our own. • Error, incompetence, incompleteness may all help

produce these potential falsifiers.• As Kuhn sees it, working within a paradigm is both

actually how we normally do science and how we normally should do science.• At least until we reach an anomaly.

Normal ScienceAnomaly• Anomaly: a puzzle that has resisted solution by the

methods of normal science.

Crisis and Revolution• A scientific revolution is a chaotic period in science

during which we abandon an old paradigm in favor of a new one. Such a revolution requires not only a new paradigm, but also a crisis.• A crisis occurs when anomalies accumulate to the

point that scientists lose confidence in the current paradigm and have incentive to embrace the new paradigm.• Most strikingly, Kuhn argued that paradigms were

incommensurable.

Incommensurability• Two or more things are incommensurable when they

are not comparable by a commons standard or measure.• According to Kuhn, paradigms came with their own

sets of (i) terms and meanings, and (ii) ways of evaluating evidence.• Paradigms were thus incommensurable in terms of • Communication• Standards of Evidence.

IncommensurabilityCommunication• Newton’s ‘mass’ vs Einstein’s ‘mass’• Various uses of the term ‘species’• The concepts falling under the term ‘probability’• Even the term ‘Earth’, Kuhn holds, once carried with it

the meaning of center of the universe.

IncommensurabilityCommunication“Now you are aware that 'universe' is the name given by most astronomers to the sphere whose centre is the centre of the earth and whose radius is equal to the straight line between the centre of the sun and the centre of the earth. This is the common account (τὰ γραφόμενα), as you have heard from astronomers.”—Archimedes to King Gelon in The Sand Reckoner

IncommensurabilityStandards of Evidence: What do we use as our standard of evidence?

An Inconsistent Triad• Objects fall straight downward.• Earth moves.• If Earth moves, then objects do not fall straight

downward.

IncommensurabilityStandards of Evidence

Classical Paradigm:1. If Earth moves, then

objects wouldn’t, fall straight downward.

2. Objections fall straight downward.

3. Thus, Earth doesn’t move.

Modern Paradigm:1. Objects fall straight

downward.2. Earth moves.3. Thus, it’s not the case

that if Earth moves, then objects wouldn’t fall straight downward.

IncommensurabilityStandards of Evidence: Should scientists be required to give causal explanations or mechanisms underlying events?• Newton’s theory of gravity gives a mathematical

description of gravitational phenomena, but he famously framed no hypothesis, no underlying mechanism.• Should he have? Was his theory incomplete?• Kuhn argued that there was no paradigm-independent

answer. Within a Newtonian paradigm, a lack of a deeper causal explanation or mechanism was tolerable.

IncommensurabilityAs Godfrey-Smith points out, the claims in Kuhn’s Chapter X are the most controversial.• Paradigms are incommensurable.• There is no objective standard by which to evaluate

their correctness, or according to which their languages can be translated.• But this means there is no objective support for the

view that some paradigms are better than any others!• We haven’t made scientific progress?!

Incommensurability“At the very least, as a result of discovering oxygen, Lavoisier saw nature differently. And in the absence of some recourse to that hypothetical fixed nature that he “saw differently”, the principle of economy will urge us to say that after discovering oxygen Lavoisier worked in a different world.”—Thomas Kuhn

IncommensurabilityGodfrey-Smith demurs:• Principle of economy?• Hypothetical fixed

nature?

But Kuhn’s statements might make more sense if we recall how classical empiricists, Locke and Berkeley, disagreed about our experiences.

IncommensurabilityGodfrey-Smith demurs:• Principle of economy?• Hypothetical fixed nature?

After all, which model is more economical, Locke’s or Berkeley’s?Which model rejects hypothetical unobservables?

Kuhn on Lavoisier

Hypothetical X No Hypothetical X

Next: Scientific Realism

Realism? Anti-Realism?