Philosophy of Science

Class 8

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Classic Tradition

• The 1950’s and 1960’s marked the high point of what is commonly referred to as the ‘classical tradition’ in science.

• What is this ‘classical tradition’? • It is a certain basic view of the world and of

science which has been shared, to some extent by all of the philosophers of science we have considered so far.

Assumptions of the Classical Tradition

• There is an outside world, which exists independent from all observers.

• The ultimate goal of science is an accurate (as possible) description of this observer independent world.

• Scientists can observe the objective natural world, in some way, and learn about it.

• the universe has underlying regularities that, if discovered can explain the behaviour of the universe.

General Agreement that…

• There is independent observation (if you had twenty scientists observing something, they would see it about the same).

• Observation is not dependent on the particular observer, and deductive logic is not dependent on the observer.

• Reality is also independent of any particular observer.

Their important conclusion:

Science is Objective!

This is good because…

It means we can use science to find out the truth about reality!

A Requirement of Science?

• The question is:• if you lose any of these assumptions, is it still

possible to even do science? • In other words, can you be a scientist if you don’t

believe in– An objective reality– A reality with causal universal laws– An objective observer (or collectively, a group of

objective observers) who are able to draw objective conclusions from objective observations of reality.

Two branches of Twentieth Century Philosophy of Science

• Branch One: Logical Positivists, Popper

• Branch Two: Duhem-Quine Thesis, Kuhn

Branch Two- stayed focused on the issue of whether or not theoretical entities actually exist.

(Both interested in truth of hypotheses)

To say that a statement is true is to say that it accurately

describes reality.

Reality of Unobservable Entities

• Suppose your theory has predictive power…

• How could it have predictive power, if the entities didn’t actually exist?

• The predictive power of theories provides independent objective proof of the reality of unobservable entities

16th-20th century: Adequate Justification

• Scientific methods, scientific theories seemed to be working!

• Science was progressing

• Just before the start of the 20th century- it looked like science was on the verge of figuring everything out!

• And then…

Some problematic theories

• General Theory of relativity

• Quantum Electrodynamics

• Heisenberg’s Uncertainty Principle

Quantum Electrodynamics

• The wave theory of light, the corpuscle theory of light

Science came up with very convincing evidence that stated that light travelled in waves.

It also became apparent, that evidence for the corpuscle theory of light could not be explained by the wave theory.

• Eventually Einstein declared that , somehow, light behaved as both a wave and a particle.

Conventionalism(Henri Poincaré (1854-1912), Pierre Duhem (1861-1916))

• The problem: theoretical statements must be either supported or refuted with

indirect tests. indirect tests involve (theoretical) auxiliary assumptions.In the face of contradictory evidence, the truth of a theoretical

statement can always be saved by stating that some auxiliary assumption is false (a la Copernicus).

The only way to test the truth or falsity of auxiliary assumptions is through further indirect tests.

But the indirect testing of the auxiliary hypotheses will involve more auxiliary hypotheses, which will need to be tested...

• This results in an infinite regress!

Conventionalism(Soft Antirealism)

• The Solution:There is a great difference between statements made

based on direct observation and statements whose truth is proved indirectly.

The truth of observational statements can be determined through observation.

However, if you try hard enough it is always possible to make any theoretical statement seem true

• Therefore, theoretical statements can never be said to be either true or false.

What kind of a solution is that!

But wait, there’s more…

• Science should still use theories!• Any number of theories can be found to help us

manage our observation statements. • Theories must be consistent with our observations,

and help us to make predictions. • We need not be concerned with their relation to

reality.• Note: Conventionalism is not denying that there is

a truth of the matter about reality.

Conventionalism Tagline:

Theoretical statements can never be declared as true or false. Theoretical

statements are merely useful in helping us to organize (cope with) our observations.

Conventionalism sounds great

But it has put us on the path to trouble!

Duhem-Quine Thesis(Strong Anti-Realism)

• William Van Orman Quine (1908-2000)• However, he took it one step further.

Poincaré and Duhem had tried to protect observation statements from the Auxiliary Hypothesis infinite regress.

They said that observation statements could be declared true or false simply by observing them (direct testing) and so they were safe from the infinite regress that befell statements that relied on indirect testing.

• Quine disagreed. He did not see a difference between theoretical and observational statements.

Trusting Observations• Consider the simple observation: “my car is

blue”.

• How would you verify the truth or falsity of this statement?

Theory of the World

• In order to verify that the car is really blue, you must already have certain beliefs like: – “The true colour of this car is apparent to me

when the sun is shining, because then the light rays correctly reflect and provide me with information about the colour of the car”.

• These beliefs are part of a theory about the world. (Your own personal theory)

• Theory? Oh no! Infinite regress!

Important Detail!

• Quine is not saying that the problem is that our senses are fallible.

• Quine is saying:– All of our direct observations are necessarily connected

to theory (through our network of beliefs)

– All theory is vulnerable to the auxiliary hypothesis problem (as shown by Duhem and Poincaré)

– Therefore- Even our direct observations are vulnerable to the auxiliary hypothesis problem.

Strong Antirealism Tagline:

There is no distinction between observation and theory. All statements are vulnerable to

revision. (All statements are neither true nor false.)

Realism Tagline:

Scientific theories describe, to some approximation, the way nature really is. Unobservable entities

really do exist.

Starting to Challenge Objectivity

• The antirealism philosophers: Picking at objectivity…

• Classic tradition: scientists can become passive receptacles for what the world wishes to reveal. (methods of Bacon,Galileo)

• The antirealists: It isn't that simple. We can't be passive observers of reality.

Subjectivity

• Reality would be said to be subjective if the nature of its existence depended on whether or not it was being observed and how it was being observed.

• A person is said to be subjective when their observations or perceptions of reality are influenced by their own beliefs, desires or experiences.

• For example, whether or not chocolate ice cream tastes good is a subjective matter.

• Not necessarily bad…

Bad for the Classical Scientists

• According to the classical tradition:• Personal Subjectivity is bad for science!

(Why?)• Scientists must be trained to be objective!• This is possible. (Bacon, Galileo)• Antirealists are starting to challenge the

idea that this is possible…• But what is the alternative? No science?

Thomas Kuhn (1922-1996)

• The Structure of Scientific Revolutions (1962): the assumptions of the classical

tradition (including the presence of objectivity in science) are bad assumptions

science works perfectly well in the absence of total objectivity.

Physicist, Historian, Philosopher

Paradigms

• According to Kuhn, every scientists approaches the world from within a particular framework of understanding.

• Kuhn calls this framework a paradigm.

• This framework shapes the way the scientist perceives the world, and determines, in part, how the world is perceived.

The origin of personal paradigms

• Fledgling scientists (i.e. those of you in this class who are doing science degrees) gain their framework by being exposed to examples of applications of the theories.

• You learn about the meaning of existing scientific theories through exposure to these examples.

• Newton’s theories (gravity? momentum?). The pendulum examples.

• By seeing how Newton’s theories are applied to this situation, I learn about the meaning of Newton’s theories.

Exemplars

• In scientific community, at a given time, has certain standard examples of how a theory might be applied- i.e. the pendulum examples.

• Kuhn called these standard examples exemplars. • By being exposed to these exemplars, students of

science come to understand the meaning of a theory, and can then go on to use it in novel contexts.

An Exemplar example

• The idea of exemplars can be applied to more than just scientific theories.

• Imagine that you want to learn the meaning of the word ‘bird’.

• Someone might teach you the meaning of this word by taking you to the zoo and showing you sparrows, robins, ducks, ostriches and penguins, each time stating “That’s an example of a bird”.

• Hopefully you will then be able to apply the word ‘bird’ correctly to new types of birds.

The origin of paradigms

• When science begins to investigate a certain aspect of nature, there are no paradigms or theories.

• Very quickly however, individuals develop their own theories about the natural phenomenon.

• Over time, these theories become more general and comprehensive- they become generic theories

• Initially, there are a number of competing generic theories, but eventually one generic theory comes to be favoured by scientists.

• This generic theory then becomes a paradigm, which will be passed on to new scientists in the area.

The value of paradigms

• They provide direction and motivation for scientists. (e.g. “I wonder what effect increased gravity has on pendulum behaviour?)

• Furthermore, they allow scientists who share the same paradigm to effectively work together and communicate their findings in a consistent and comprehensible manner.

Using Paradigms

• Scientists will look for ‘facts’ relative to and try to solve puzzles relative to their paradigm.

• Scientists will seek out observations that support their paradigms.

• Scientists will try to clarify and expand the paradigm by developing precise laws, accurately measuring physical constants and applying their paradigm to new phenomena not yet specifically covered by the paradigm.

Paradigm Example• Atomic Paradigm:

– Everything is composed of small indivisible particles called atoms.

– Different substances are composed of different types of atoms, or, sometimes, different combinations of types of atoms.

• Phlogiston Paradigm:– Everything is composed of water, air, earth or fire, in some

combination. (Phlogiston was the name given to the essence of fire).

– Different combinations of these four substances lead matter to provoke different sensations in people.

Applying the two different paradigms

• look for ‘facts’ relative to and try to solve puzzles relative to their paradigm. Atoms vs..... Phlogiston…

• Seek out observations that support their paradigms. Atoms vs........ Phlogiston

• Try to clarify and expand the paradigm by developing precise laws, accurately measuring physical constants and applying their paradigm to new phenomena not yet specifically covered by the paradigm. Atoms vs..... Phlogiston

Normal Science

• A particular paradigm will provide scientists with both problems to solve and expectations of what solutions they will find.

• Most of the time, this is how science progresses. (normal science).

• However, occasionally, events arise that result in an overthrowing of the existing paradigm and its replacement with a new paradigm.

• The new paradigm is often radically different and not compatible with the old paradigm.

Scientific Anomalies

• What causes the overthrowing of an existing paradigm?

• Generally speaking paradigms are quite stable. If observations or results are not compatible with the paradigm they tend to be ignored or their relevance diminished in scientific circles.

• Sometimes, however, an anomaly is so problematic that it can’t be ignored.

Scientific Crisis!

• Suppose a problem is too large for science to just ignore.

• In this case, scientists might try modifying some parts of their existing paradigm (e.g. changing or adding auxiliary hypotheses).

• Every effort will be made to hold onto the paradigm.

• Eventually, however, too many of these anomalies may build up, precipitating a crisis in that area of science.

Scientific Revolution

• When a crisis occurs, a new paradigm is sought out to replace the existing paradigm.

• Kuhn called the event where one paradigm was rejected and another found to replace it a scientific revolution.

Incremental Progress

• Generally speaking, the old paradigm and the new paradigm are not compatible. Facts in one do not translate into facts in the other.This runs contrary to the commonly held idea that, over time, science gradually increases its knowledge about the natural world.

• Kuhn describes different paradigms as being incommensurable

Differences between Paradigms

• According to Kuhn, no aspect of the paradigms are spared this incommensurability.

• Paradigms do not share: Facts Problems and solutions Terms (even if they happen to have the same form, they

do not share meaning) Statements or subject matter

Kuhn’s Strong Position

• Can Kuhn really mean what he is saying here?

• Wouldn’t measurements and basic observations (like “Smoke rose into the air”) still be consistent across paradigms?

Paradigm- A world filter

• According to Kuhn, a paradigm is like a filter that affects every aspect of the way we perceive the world.

• To gain a better understanding of what this means, consider the following analogy- the helmet analogy:

• All scientists wear special helmets, which transmit to them the sights, sounds, smells, of the real world. However, the helmet also acts as a filter and changes this sensory information when it is passed to the scientist.

Different Paradigms, Different Worlds

• For scientists whose helmets have the same filter, the world will appear the same.

• For scientists who do not share the same filter, even simple observations will be experienced differently.

• A paradigm is like one of these filtering helmets. It completely determines our perspective of the world.

• Kuhn believes we need the filter provided by the paradigm in to have any understanding of the world.

Kuhn the Relativist?

• Kuhn does not think that different paradigms provide more or less accurate version of reality.

• Returning to our analogy, it is not that some helmets have less of a filter than others.

• Given this, does Kuhn think that any one paradigm is any better than any other paradigm?

• This is similar to the question we discussed earlier about theories- how do you decide which theories are better than other theories?

Kuhn Tries to avoid Relativism• Kuhn most emphatically does not wish to be considered a

relativist. • He develops a number of criteria on which to compare paradigms.• Briefly, they are (Hung p.384):

– Problem solving ability– Quantitative Precision– Predictive power (ability to make unexpected predictions)– Consistency– Simplicity– Aesthetics– Future Promise

Evolutionary Science

• Kuhn does thinks that the paradigms of science, over time, get closer and closer to meeting his criteria- automatically!

• How does he think this happens?

• Kuhn was a fan of Darwin’s theory of evolution and believed that, in some sense, it was applicable to the generation of paradigms in science.

Evolving Paradigms

• Kuhn believed that paradigms are chosen through an evolutionary process.

• Multiple paradigms compete with each other for selection by the scientific community.

• The paradigm that is the fittest (based on the criteria proposed by Kuhn for evaluating paradigms) is selected as the current paradigm.

• New paradigms are created by scientists and are enter in the ‘paradigm competition’.

Kuhn and Truth

What is Kuhn’s position on truth (and falsity)?• Kuhn doesn’t think the idea of truth really makes much

sense.• Remember that our earlier definition of a true statement

was a statement which accurately corresponded with the way ‘the world out there’ existed.

• According to Kuhn, the statements we make and the ‘facts’ we discover are determined by which paradigm we have.

• Consequently the idea of truth doesn’t make sense.

Differences between Kuhn and Classicists- I

• Classic Science: – Science depends for its success on critically

assessing proposed hypothesis. – Science must determine, as rigorously as

possible, the truth value of proposed hypothesis

• Kuhn:– Science is not about critical inquiry. Rather

science is about maintaining the status quo (whatever it may be at the time)

Differences between Kuhn and Classicists- II

• Classical Science: – Testing is critical in science- in particular for

determining the truth and falsity of theories

• Kuhn: – Science operating under a paradigm does involve

testing, but the testing does not address the validity or truthfulness of the paradigm itself.

– Testing only exists to test consequences or facts that are derived within the context of the paradigm.

Differences between Kuhn and Classicists- III

• Classical Science: – Science allows for the steady accumulation of

knowledge about the natural world.

• Kuhn:– Science is cumulative while operating under a

particular paradigm, but when this is overthrown and replaced by a new paradigm, science must begin collecting ‘knowledge’ from scratch again.

Criticisms of Kuhn

• There are two main directions taken in criticisms of Kuhn:

• The relativist direction

• The objectivist direction

The Relativist Direction

• Kuhn wished to deny that he was a relativist, but his theory of paradigms is perilously close to being relativistic.

• The only aspect of Kuhn’s philosophy which saves him from this are his criteria for evaluation of paradigms.

• However, even Kuhn acknowledges that these criteria are vague and difficult to explain precisely. He intends them only as guidelines, rather than as rules for good paradigm creation

Embracing Relativism

• Consequently, philosophers often say that Kuhn cannot avoid being a relativist, despite his efforts.

• Some philosophers, like Paul Feyerabend (1924-1994), embraced relativism in science (and in general).

• These philosophers say Kuhn’s theory of science is relativist, but that is just fine!.

• Other philosophers who believe that science is not relative say that this reveals the incorrectness of Kuhn’s ideas.

The objectivity direction

• Other philosophers argue that Kuhn is wrong when he tries to suggest that science is subjective.

• Their objections typically involve attempts to find problem with Kuhn’s conception of paradigms and how science functions using these paradigms.

• For instance, Israel Scheffler (1923 - present) argues, among other things, that basic observations, at least, are consistent among scientists, regardless of their personal biases or the theories held by them.

Lakatos- An attempt to compromise

• Kuhn’s philosophical ideas were too controversial to be adopted wholesale by the philosophical or scientific community.

• However, they were taken seriously enough that a serious effort was made to incorporate aspects of Kuhn’s ideas into the traditional view of science.

• In particular, Imre Lakatos (1922-1974) tried to develop a comprehensive philosophy of science that integrated Popper and Kuhn.

• How could Lakatos hope to unify two such seemingly disparate theories?

Combining Popper and Kuhn

• Recall that, for Popper, the most important aspect of science was its effort to falsify proposed hypotheses.

• Even though this seemed like a promising and original idea, we discussed a number of serious problems with Popper’s efforts to make falsification the core of scientific practice.

• Lakatos tries to fix this by redefining the idea of falsification, using some ideas put forward by Kuhn (and Feyerabend).

Competing Theories

• According to Lakatos, falsification of a theory only occurs relative to another theory.

• Lakatos says that that a theory is false if it is compared with a competing theory and:– The new theory has higher empirical content- which means

that it predicts some facts that aren’t predicted by the original theory

– The new theory manages to explain all of the observations that the old theory could explain- it encompasses the old theory

– Some new aspect of the new theory have already been corroborated.

A strange characterization of ‘False’

• If a new theory meets all of these criteria then the old theory is considered to be falsified, relative to the new theory.

• The new theory can be said to be better than the old theory, and should be adopted by science.

• We can see that this isn’t the idea of falsified that we tend to use. Lakatos still called this ‘falsification’ because of the parallels to role of falsification in Popper’s theory.

An Objective Kuhn? A Subjective Popper?

• When considering Lakatos we can see how he tried to reach a compromise between Popper and Kuhn by:

• Changing some of Popper’s ideas to make them more subjective (like his idea of falsification)

• Changing some of Kuhn’s ideas to make them more objective (like his idea of paradigm shifts)

Present Day Philosophy of Science

• We have arrived at present day philosophy of science!• Philosophers of Science continue to scrutinize science…• With new scientific activities they ask- is this really

science? Is it following the accepted methods of science?

• With science in general they debate issues like- how objective/subjective is science? Is objectivity/subjectivity good or bad in science? What role should science play in our society?

Next Week- Final Test

• Included some review questions in last week’s slides

• This week talked about– Classical Science (and philosophy of science)– The realism/anti-realism debate– Kuhn’s theory of science

Some questions to get you thinking about…

• The Classical Tradition– What was the classical tradition? What

characterized the classical tradition? When did it start and stop? What assumptions did classical science make? What caused the classical tradition to be cast aside by some scientists and philosophers? How does philosopher x’s theory compare with the assumptions of the classical tradition (e.g. Comte, Popper, Duhem, Quine, Kuhn, etc. etc.)

Some questions to get you thinking about…

• The realism anti-realism debate– What was the realism/anti-realism debate? Which

philosophers are anti-realists? Why are they called anti-realists? How many types of anti-realism did we discuss? What is the difference between soft and hard anti-realism? What is the difference between Duhem’s and Comte’s thoughts/arguments regarding theoretical entities? Did Quine agree with Duhem? If yes, in what way? If no in what way? State Duhem’s argument. State Quine’s argument. Are you convinced by Duhem’s argument? If yes, are you convinced by Quine’s argument? If no, how can you save Duhem’s argument from Quine?

Some questions to get you thinking about…

• Subjectivity/Kuhn– Define subjectivity. Define Objectivity. What is the

difference between saying that the world is subjective and saying that a person is subjective? Why did scientists in the classical tradition think that subjectivity was so problematic for science? What did Kuhn think about subjectivity and science? If Kuhn said subjectivity was okay and the classicists said it wasn’t- what led them to such different conclusions about subjectivity? How does Kuhn describe the progression of science? According to Kuhn, how does a person become a scientist. Describe the historical progression of science, according to Kuhn. Cont…

Some questions to get you thinking about…

• Kuhn, cont…– What stages does science pass through, according to

Kuhn? What is the connection between Kuhn and evolution? What are some criticisms of Kuhn? How did Lakatos attempt to unite the classic tradition and Kuhn’s theory?

• General– Can you create a timeline of all philosophers discussed

after the midterm? Can you say what their major theory was, what motivated them to create their theory and two problems with their theory?