Foundation of psychology
Chapter 9
What is science?

Science’s claim of superiority was based on four principles

• Realism:
  There is a physical world with independent objects, which can be understood by human intellect
• Objectivity:
  Knowledge of the physical world does not depend on the observer.
  ‘Objective’ agreement among people is possible, irrespective of their worldviews.
  • Science aims to uncover this knowledge so that it becomes public, verifiable and useable
• Truth
  Scientific statements are true when they correspond to the physical reality
• Rationality
  Truth is guaranteed because scientific statements are based on sound method.

Thoughts about information acquisition from Ancient Greece to the end of the nineteenth century

Thoughts before the scientific revolution

Plato, Aristotle and the sceptics

Plato
A strong rationalist view of knowledge acquisition.
Human perception was fallible and the observable world was only a shadow of the Real world.
The human soul had innate knowledge of the universe, which could be harnessed

Aristotle
More scope for observation and made a distinction between deductive reasoning and inductive reasoning.
True, theoretical knowledge started from axioms, form which new knowledge was deduced via so-called demonstrations.
Perception was the source of information but not knowledge itself.
Correspondence theory of truth: a statement is true when it corresponds with reality. Assumes that there is a physical reality which has priority and which the human mind tries to understand it. First formulated by Aristotle.

Pyrrho of Ellis
Scepticism: philosophical view that does not deny the existence of a physical reality, but denies that humans can have reliable knowledge of it; first formulated by Pyrrho of Ellis.
Humans must suspend judgment on all matters of reality.

Augustine

Augustine (354-430CE)
True knowledge was knowledge based on God’s revelations.
This view became dominant until well into the seventeenth century.

Interaction between theory and experiment: the scientific revolution

Galilei’s thought experiments

Galilei is usually credited as the person who convinced the world of the importance of observation and experimentation for the acquisition of knowledge.
But Galilei might in reality be a transition figure steeped in the Aristotelian tradition.

• Galilei referred more often to thought experiments than real experiments in his writings
• Galilei may have derived his law of motion from real experiments, but he did not use them to convince readers
  • He did not consider them as decisive and he knowledge that his audience would not buy them either
    True knowledge was knowledge resonating with human understanding

Bacon: induction

Francis Bacon promoted the use of systematic observation and inductive reasoning as the road to new knowledge.
Instead of demonstrated knowledge or divinely revealed knowledge, an inductionist approach had to be followed.

• When investigating a new topic, Bacon recommended beginning with the collection of a large number of facts on a mechanical way, without theoretical prejudice, and put them into tables for better understanding.
  • When deriving conclusions from the tables, Bacon warned readers not to jump to conclusions
• Bacon warned readers not to search exclusively for positive evidence, but to make use of three types of tables
  • Essence and Presence
    All instances in which the phenomenon under investigation was present
  • Deviation or absence in Proximity
    A list of instances matched to the first table in which the phenomenon was absent, even though the circumstances were similar
    This way one could see what instances were critical for the phenomenon.
  • Degrees or Comparison
    Instances in which the phenomenon was present in different degrees
• When examination was done this way, Bacon was adamant what it would lead to true, scientific information about the world
  Truth could not be obtained by simply observing Nature, it had to be extraced from her.

von Leibig (1863)
Ridiculed Bacon.
What was the point of fact collection if there was no question or goal behind it?
Science started from the researcher’s imagination, not from blind data collection.

Newton

Isaac Newton
Advice regarding science was deeply ambivalent about the roles of theory and observation, to such an extent that it can be used as an illustration of both Aristotle’s deductive approach and Bacon’s inductive approach.
In 40 years, Newton seems to have shifted his preference from deduction to induction.
In Newton’s eyes, the scientific method was not so different from Aristotle’s demonstrations based on deduction, except for the fact that the first principles had to be based on observation, experimentation and inductive reasoning, rather than self-evident axioms.

Probabilistic reasoning and the ascent of hypotheses

Inductive reasoning and probable truths

Inductive reasoning was disapproved of up to (and including) the scientific revolution because it did not guarantee true conclusions.
Only deduction was legitimate, as proven by the success of mathematics and geometry.

There was little denying that inductive reasoning was exactly what the new scientists were doing, backwards reasoning from observed effects to probable causes.

Two critical assertions from Christian Huygens:

• It was possible to verify principles form their effects with a degree of probability that was scarcely less than complete proof, when a great number of (observable) phenomena in line with the principles were collected
• Truth was particularly guaranteed when the principles in addition allowed researchers to make new predictions and to verify them

Definition of probability

Induction did not lead to necessary truths but to ‘highly probable conclusions’.
This required a definition of probability.
Two definitions were proposed

• Mathematical
• The degree of belief

An increased appreciation of hypotheses

As the appreciation of inductive reasoning for the advancement of knowledge grew, hypotheses also received a more positive evaluation than had been the case with Newton (who was against hypotheses).

John Herschel (1792-1871)
Although scientific reasoning started from observation, it became increasingly more abstract.
Observation-independent scientific reasoning led to truth if done carefully.
Because scientific theories were to some extent speculative, Herschel acknowledged that it was possible to have different views of the same phenomenon.
The temporary co-existence of rivalling theories was not bad, because a choice could be made between them by formulating hypotheses and seeing which hypotheses accounted best for the findings.

Theories influence observations

A final insight formulated before the twentieth century was the distinction between observations and ideas was not as clear as traditionally assumed by philosophers.
Fact and theory depended on each other

Whewell

William Whewell (1794-1866)
Called the distinction between thoughts and things, theory and fact ‘the fundamental antithesis of philosophy’.
Reason why the fundamental antitheses of philosophy was wrong (according to Whewell)

• Fact and theory could not be separated

It was an illusion to think they referred to neatly distinguished entities

Comte

Acknowledged the influence of theory on observation.

Idealisation of scientific knowledge

Much of the doubts about the status of scientific knowledge were forgotten towards the end of the nineteenth century, when the writings of the positivists dominated.
Science’s victory march was used as an argument to sweep the more critical passages on the scientific method under the carpet.
The doubts were rarely read, let alone taught to future scientists or communicated to the wider public.

Interim summary

Thoughts before the twentieth century

• To a great extent, the rise of the scientific approach can be summarised as a shift in balance from deductive reasoning to inductive reasoning. Before the scientific revolution it was generally accepted that only deductive reasoning led to necessary truth (Plato, Aristotle)
• The men of science at first tried to convince their audience that the new way of thinking was very close to traditional deductive reasoning and demonstration (Galilei, early Newton)
• Gradually natural philosophers started to argue that inductive reasoning could lead to conclusions as probable as truth, when facts were collected in large numbers and without prejudice, when effects could be replicated, and when theories led to new verifiable predictions (Bacon, Huygens, later Newton, Bayes, Laplace, Herschel)
• Whelwell and Comte further pointed out that there was no clear distinction between observation and idea, between fact and theory. They are closely interconnected and influenced each other.
• As a result of the successes of science, most of the initial doubts about whether inductive reasoning could lead to true conclusions were swept under the carpet towards the end of the nineteenth century

The first twentieth-century attempt at demarcation: observation, induction and verification

Philosophy of science and the demarcation of science

In the early twentieth century a group of philosophers and scientists decided to revisit the specificity of the scientific method.

Demarcation: setting and marking the boundaries of a concept; used, for instance, in the philosophy of science to denote attempts to define the specificity of science
Philosophy of science: branch of philosophy that studies the foundations of scientific research, to better understand the position of scientific research relative to other forms of information acquisition and generation.

Logical positivism

The Vienna Circle

Moritz Schlick (1882-1936)
Wiener Kreis (Vienna circle) in the 1920s
Logical positivism: philosophical movement in the first half of the twentieth century, claiming that philosophy should stop thinking about metaphysics, and instead try to understand the essence of the scientific approach; central tenet was the verification principle.
Scientific knowledge was true knowledge.

The 1929 manifesto

The Wiener Kreis made the following conclusions in a manifesto:

• Truth divides into two types
  • Empirical truths
  • Logical truths
• Empirical truths make claims about the world and are established through empirical verification (observation and experiment)
• Logical truths are based on deductive logic and are influenced by linguistic conventions
• Statements not belonging to one of the categories above are meaningless

According to the logical positivists, science proceeded by means of a cycle consisting of

• Observation
  Careful observation of what happened
• Induction
  Translation of individual observations into general conclusions on the basis of inductive reasoning
  Ideal was formulation of a mathematical law
• Verification
  This was seen as the demarcation criterion of science
  • A statement was scientific if and only if it could be verified as true or false through objective, value-free observation
    Verificationism: adherence to the principle that a proposition is meaningful only if it can be verified as true or false; with respect to science states that a proposition is scientific only if it can be verified through objective, value-free observation

The logical positivists also accepted deductive reasoning as a way of making meaningful statements.
But this type of reasoning could only be used to deduce conclusions from what was already known. It did not generate new knowledge.
The ensuing statement had to be verified anew

Problems with the verification criterion

Verification is logically impossible

It is logically impossible to prove the truth of a conclusion on the basis of repeated observations.
In order to move from observation to a general conclusion, one needs inductive reasoning, and inductive reasoning does not lead to conclusions that are guaranteed to be true according to the rules of logic.

Scientific theories are full of non-observable variables

Many scientific theories include non-observable variables.

To solve this problem, logical positivists had to accept that not all variables in scientific theories needed to be directly observable, as long as they involved dimensions that could be measured in relatively simple ways.
If you could express variables in numbers by referring to the ways in which you measured them, the resulting law was fine.

How should we define ‘observable’?

Although the criterion that non-observable variables in scientific theories should have an operational definition solved some problems, it was not watertight.
Some variables require complex, indirect methods to be revealed.
Any dividing line between observable and non-observable ultimately turned out to be an arbitrary distinction.

Non-observables may become observable

Over time, many initially hypothesised, non-observable phenomena became observable, because of technical improvements and because the theory allowed the scientists to know what they were looking for.
This raises the question of how to make a distinction between hypothesised non-observables that turn out to be empirically verifiable and hypothesised non-observables that turn out not to exist.

Verifiable observations are no guarantee of correct understanding

There are many occasions on which erroneous scientific conclusions had been drawn from empirically verified ‘facts’.

Positivism as naive idolatry of science?

All in all, rather than solving the demarcation problem of science, the logical positivists testified to the difficulty or maybe the impossibility of doing so.

Another descendant of logical positivism’s failure: a new look at the meaning of words

The demarcation problem not only called positivism into question, it also led to a completely different understanding of language.

Wittgenstein
Language was a faithful depiction of the state of affairs in the world and so the world could be known by analysing the logical structure of language.
By analysing the meaning of the words and interrelations, one could get insights into the physical reality.
But, the impossibility of conclusively defining science made Wittgenstein realise that the same was true for many other words in the language.
The meaning of words was determined by their use in a social context, which Wittgenstein called language games.
The meaning of words depended on the circumstances in which they were used.
They did not have fixed meanings, objectively depicting the physical reality, as Wittgenstein originally thought.

Interim summary

Logical positivism

• Logical positivism tried to reconcile the practical success of sciences with the methodological concerns formulated by philosophers
• It tried to define demarcation criteria for science that would be universal and ahistorical, and that could be applied to other knowledge areas
• The movement found prominence with the publication of the 1929 manifesto of the Vienna Circle
• The most important demarcation criterion put forward for empirical truths was empirical verification
• Almost immediately, however, the criterion met with a series of objections
  • Verification does not solve the induction problem
  • Scientific theories are full of variables that cannot be observed directly
  • There are no demarcation criteria that unambiguously define ‘observable’
  • Sometimes things are not observable until one knows how to search for them
  • Verifiable observations do not guarantee a correct understanding
• Because of the many criticisms, logical positivism failed, which gave positivism a negative connotation of naive belief in the power and the truthfulness of scientific research

The second twentieth-century attempt at demarcation: falsification

Preliminary: perception is more than sensing stimuli

Perception requires interpretation

When the logical positivists claimed that science was special because it was based on facts, they assumed that facts could be perceived prior to and independently of any theoretical framework, and that the perception of facts was the same for all careful observers.
But there is considerable evidence that this is not the case.

• Perception involves interpretation of sensations.

A theory changes the perception of the facts

The understanding of a scientific phenomenon involves more than simply sensing the isolated facts.
It involves an element of interpretation to understand what the different facts mean and how they relate to each other.
Once such an interpretation has been found, the meaning of the originally observed facts changes spectacularly.

A theory enables scientists to focus on the important facts

A theory not only changes the perception of facts, it allows scientists to search in a more directed way.
It helps them to sort out the avalanche of facts and to decide which facts are important and which are not.
Without a theory scientists do not know which observations are important and which are not.
What humans observe depends on what they know (or think they know).
The more observers know about a particular phenomenon, the richer their perception.

Popper: falsification instead of verification

Science constantly questions its explanations

Karl Popper (1902-1994)
Fully accepted the importance of theories in scientific thinking.
What distinguishes science from non-science is that the formed is based on facts (observations, verifications) and the latter on ideas (dogma, prejudices).
Both proceed by constant interactions between observation and interpretation.
What sets science apart is that it constantly questions its explanations, whereas non-scientific movements have no such inclination.

Falsification instead of verification

Popper argued that what distinguishes scientific from non-scientific theories is that scientific theories are falsifiable.
Falsificationism: view within the philosophy of science that statements are scientific only if they can be falsified empirically.
A theory is falsifiable if it rules out a range of outcomes, or if there is agreement about observations that would be incoherent with the theory and, therefore, refute the theory.

Whereas it is impossible to prove the truth of an inductive conclusion, it is easy to prove the falseness of an inductive conclusion.
All you need is a counterexample.
Hypothesis testing should not be directed at trying to confirm a theory, but at seeing whether the theory could be falsified.

• If the researcher repeatedly tried to reject a theory and failed to do so, they had strong evidence about the correctness of the theory.
• As soon as a test failed the theory, they knew the interpretation was a false trial

The hypothetico-deductive method

Hypothetico-deductive method: model introduced by Popper to understand the scientific method; on the basis of observation, induction and educated guesswork, a theory of a phenomenon is formulated; the correctness of the theory is evaluated by the formulation of a testable prediction (hypothesis) on the basis of deductive reasoning; the prediction is subsequently put to a falsification test, which provides new observational data for further theorising.

Degrees of falsifiability

There were different degrees of falsifiability, dan the degree to which a statement or theory exposed itself to falsifiability was informative.
The more falsifiable a theory was, the higher its scientific status.
The clearer and the more precise a theory, the higher its status if it stands repeated falsification tests.
And the more facts a theory explains, the better it is.

Implications of Popper’s proposals for science’s status

Science proceeds by trail and error

Popper was the first philosopher of science to accept that scientific explanations could be wrong, even when they initially seemed to be in line with the collected evidence.
He argued that scientist were never fully sure of the correctness of their scientific explanations, given that these were based on inductive reasoning.
All the scientists could say was that a particular theory thus far had passed the various falsification tests and, therefore, was likely to be correct.
They also had a lot of information about explanations that were wrong, because they did not pass the falsification test.

• Theories can be proven false, but cannot be proven true.
  They are just the best available, the ones that (thus far) have passed the tests

The progress in science is best seen as a process of trial and error, in which many possible explanations are ventured and only the fittest survive.
The ruthless falsification ensures that scientists are less likely to stick to wrong opinions than people who do not critically evaluate their opinions.

Falsification goes against human intuition: the confirmation bias

When confronted with arguments, humans have a tendency to assess the validity of the statement by searching for corroborating evidence rather than trying to make sure there is no possibility to refute the statement.
Confirmation bias: tendency people have to search for evidence that confirms their opinion; goes against falsificationism.

The application of the falsification criterion turned out to be more complicated than at first thought.

Sophisticated falsificationism

Do not give in too easily

Problems

• The idea that theories should be rejected as soon as they were falsified did not seem in line with the way in which scientists worked.
  Scientists did not throw away a theory as soon as some data contradicted it
  • They investigated whether the data were sound, so that they did not reject the theory on flawed grounds
  • If they were convinced of the soundness of the evidence, they examined whether the theory could be amended so that it incorporated the new finding

Science is more than simply rejecting falsified bold conjectures and replacing them with equally bold alternative conjectures.
Often it is better to adapt an existing, good theory so that it is no longer contradicted by the available empirical evidence.
Even Popper agreed that scientists should not give up their theories too easily.

Modifications of theories in the light of counterevidence

If modifications of existing theories are allowed, the next question is which modifications are acceptable and which are not.

• Modification must under no condition make the theory less falsifiable
• The theory should become more falsifiable as a result of the modification

Ad hoc modifications: modifications to a theory that according to Popper make the theory less falsifiable; decrease the scientific value of the theory

Why researchers do not like to give up theories

Rejecting a theory means the scientists have to start all over again.
They have to search for a new, plausible theory that explains everything the previous theory explained plus the novel, contradicting finding.

Interim summary

Popper’s falsification alternative to logical positivism

• Science is better considered as the formulation of theories (on the basis of inductive reasoning and educated guessing) that scientists subsequently try of falsify by deriving hypotheses which are put to the falsification test; this is the hypothetico-deductive method.
• There is no guarantee that an initially proposed theory is correct; therefore, science proceeds by trial and error
• Science differs from on science because
  • The theories can be falsified
  • There is a willingness to do so
• Falsification is a better criterion than verification, because it is logically possible to falsify a statement based on inductive reasoning
• The more falsifiable a theory is (depending on its level of detail and scope), the better the theory is
• Falsification is counterintuitive because people have a bias towards trying to confirm their opinions rather than trying to reject them
• Limitations to falsification
  • Popper’s insistence on replacing falsified theories by bold alternatives as soon as they are contradicted by empirical observations does not agree with scientific practice and would also seem to be too radical
  • When researchers are confronted with conflicting evidence, they first try to modify the existing theory so that it can account for the contradictory finding
  • According to Popper, modifications are acceptable as long as they do not make the theory less falsifiable; otherwise, they are unacceptable ad hoc modifications
  • Problem: researchers regularly propose modifications they do not test and that are not taken up by other researchers. Is this still science?

Science is a succession of paradigms

Thomas Kuhn (1922-1996)
Agreed with Popper about the priority of theory over observation.
All observations and theoretical concepts were dependent on the language of the adopted theory/conjecture.
Only certain research questions are considered to be of interest by the majority of researchers; in addition, these questions must be examined in well-specified ways.

The general layout of Kuhn’s theory

Pre-science → normal science → crisis → revolution → new normal science → new crisis → …

Pre-science

Research discipline starts with an unorganized amalgam of facts, observations and models to explain small-scale phenomena.
Researchers try to understand isolated facts without having an idea of the wider framework.
As a consequence, their explanations often contradict each other.
They also do not agree about the methods to use

Creation of a paradigm

At some point in time, a general framework (theory) is proposed.
This not only informs the researchers about the interrelations of the various blobs, but they also gain an idea of the methods that must be used to properly investigate the different facts.
Paradigm: notion introduced by Kuhn to refer to the fact that scientists share a set of common views of what the discipline is about and how problems must be investigated.
A paradigm will determine

• What is to be observed and scrutinised
• Which questions should be asked
• How the questions are to be structured
• How the results of scientific investigations should be interpreted

Normal science

Once the researchers share a paradigm, the discipline finds itself doing normal science.
This involves attempts to falsify the theory, to see how strong the theory is.
If there is a consistent deviation between the theory and a line of findings, a modification or extension is introduced to capture the intractable fact without changing the core of the paradigm.
Although there is no specific ban, researchers are not expected by their colleagues to question the paradigm and to come up with incommensurable, bold conjectures.
Researchers are guided by the rules of the paradigm

Crisis and revolution

Inevitably, the phase of normal science will yield results that cannot be accounted for by the paradigm.

1. First, these findings are seen as anomalies, unexplained observations, rather than falsifications, and researchers will question the quality of the findings or look for ways in which they can be explained with the use of modifications to the existing theory
2. The anomalies will multiply and become more severe
   They will require an increased use of ad hoc modifications and changes to the theory that other researchers do not find interesting enough to test
3. The original framework will become increasingly incoherent and cluttered, resulting in a state of affairs very similar to the pre-science situation
   Scientific progress stalls and confidence in the paradigm is undermined.
   The discipline finds itself in a state of crisis

At the time of the crisis, a scientific discipline is more open to bold, alternative conjectures that question the core of the paradigm
These alternatives must provide the same level of detail and falsifiability as the existing paradigm and, in addition, provide a better interpretation for the deviating findings.
Scientists are looking for a conjecture that allows the discipline to make progress again, to yield new predictions that can be falsified and stand the test.

Imre Lakatos

• Degenerative research paradigm: a paradigm that does not allow researchers to make new predictions and that requires an increasing number of ad hoc modifications to account for the empirical findings
• Progressive paradigm: a paradigm that allows researchers to make new, hitherto unexpected predictions that can be tested empirically

Kuhn called the replacement of a paradigm in crisis an incompatible, new paradigm that makes new predictions and that repeatedly stands the falsification test, a scientific revolution.
During a scientific revolution a paradigm shift takes place, in which the old paradigm is replaced by a new paradigm.
This is a time of intense scientific progress.

Return to normal science

Once a paradigm shift has taken place, the new paradigm takes over and forms the new background against which research occurs.
After rapid changes and excitement of the revolution, the situation returns to normal and the scientists go back to their usual activity.
They will defend the new paradigm with the same vigour as they defended the previous paradigm.

On the relativity of paradigms and he science wars

Paradigms are ever changing

Each paradigm is considered to be a temporary set of ideas, bound to turn into a crisis to be replaced by an alternative paradigm.
So current scientific knowledge cannot be considered as absolute truth but must be seen as a transition from the previous paradigm to the next.

The unbearable lightness of science

Kuhn was unclear about whether a revolution meant progress of simply a change of paradigm.
Kuhn’s analysis rekindled the controversy between realism and idealism.

Realism

• Concepts used in human knowledge refer to a physical reality which has priority
• Knowledge is discovered rather than created
• Truth is determined by the correspondence between knowledge and the physical world

Idealism

• The world as we know it is a construction of the mind
• Human knowledge is a subjective or social construction that does not necessarily correspond to the outside world
• All knowledge is affected by language and culture
• The truth of statements depends on their coherence with the rest of the knowledge

George Berkeley (1685-1753)
If one assumes that all knowledge is based on observation, then there is no guarantee of an outside physical reality corresponding to the knowledge.
The only thing that is real for people is perception itself

Kuhn’s scrutiny suggested that all scientists were doing was creating a set of stories about perceptions (idealism), shrouded in a secretive language (jargon) and adorned with an unjustified air of objectivity, which in a hundred years time would be looked upon as another outmoded paradigm based on wrong assumptions.

The science wars

Postmodernists: in the philosophy of science, someone who questions the special status of science and sees scientific explanations as stories told by a particular group of scientists.
According to post-modernists scientific knowledge was a social construction by the scientific community, affected by their language and culture.
Social construction: notion used by postmodernists to indicate that scientific knowledge is not objective knowledge discovering the workings of an external reality, but a story told by a particular scientific community ion the basis of language and culture.
The truth of scientific statements depends on how coherent they were with the rest of the paradigm shared by the group.
Scientific knowledge was not superior to other types of knowledge.

Science wars: notion used by the postmodernists to refer to their attacks against the special status of science and their unmasking of scientific knowledge as a social construction.

Interim summary

Kuhn’s theory

• A discipline needs a general theory to become scientific, otherwise it is pre-science. This theory forms a paradigm against which observations are made, questions are posed and answers interpreted
• During periods of normal science, scientists solve puzzles within the existing paradigm. They defend the paradigm and ostracise colleagues who question it. Modifications of the theory in the light of contradictory findings must stay within the paradigm. Otherwise the findings is an unexplained anomaly
• During a period of normal science, anomalies accumulate and modifications become increasingly ad hoc. This triggers a crisis
• During a crisis, scientists are more open to an alternative, incommensurable theory, if the latter provides the same level of explanation and in addition allows the formulation of new predictions that stand the falsification test. If such an alternative is found, a paradigm shift takes place, which Kuhn calls a scientific revolution
• Because of these scientific revolutions, scientific progress is not steady and cumulative. During the revolution progress is very fast; at the end of a period of normal science, progress is very slow or non-existent
• The cycle of periods of normal science followed by scientific revolutions is never-ending.
• Paradigm shifts in Kuhn’s theory do not imply that the old paradigm is replaced by a better one; it is just replaced by another one
• This means that all scientific knowledge is relative and time-dependent, because it is based on a paradigm that is bound to be replaced in the future
• The awareness that scientific knowledge is relative has elicited strong criticism from the postmodernists. In their view science is in no way superior to other types of knowledge, because it consists of social constructions made up by the scientists. Scientists have more power because they have formed strong alliances with other powerful groups

The pragmatic alternative

Peirce and pragmatism

Charles Peirce (1839-1914)
Success in coping with the physical reality could be taken as the criterion to decide how worthwhile knowledge is.
Pragmatism: view within philosophy that human knowledge is information about how to cope with the world; the truth of knowledge depends on the success one has in engaging with the world, on what works.
The truth of a theory is only of interest if it makes a practical difference.
Because the world constantly changes, the truth is not fixed either.

Why pragmatism was overlooked for a long time in the philosophy of science

Pragmatism did not seek to draw a distinction between scientific knowledge and non-scientific knowledge

Peirce made a distinction between four ways of gathering knowledge

• Scientific method
• Method of tenacity
  People hold assumptions and beliefs because they have been around for a long time
• Method of authority
  People form opinions by consulting ‘experts’
• The a priory method
  People use their own reason and logic to reach conclusions

According to Pierce, there was no clear difference between the scientific method and the three other methods of knowledge acquisition.
All knowledge that helped to cope with the world was useful, wherever it came from.

Renewed interest in pragmatism

Pragmatism does not require a stance for or against the existence of an independent physical reality.

Interim summary

• A strong component of the discussion within the philosophy of science is the extent to which human perception and understanding correspond to a physical reality. This is known as the realism vs. idealism debate.
• Another view is that knowledge of reality is derived from successfully coping with the world. Ideas that work are retained; ideas that do not make a practical difference get lost. This is the pragmatic view
• The pragmatic view has been ignored for a long time, because it does not give a special status to scientific knowledge, but currently seems to be gaining momentum

Focus on: how to respond to scientific knowledge

• The strong relative view of scientific knowledge is based on the assumption that the perception of facts is fully dependent on the perceiver’s background knowledge
• If one accepts that the perception of facts has an objective component, grounded in reality, then the constant coupling of ideas to observations by means of verification and falsification is a guarantee that the ideas will not be completely in contradiction with the reality as it can be observed
• The observation that science proceeds by trial and error and happens within a paradigm that may turn out to be wring should warn people always to remain critical about scientific claims. A helpful rule of thumb in this respect is to always look at how many falsification tests the claim has stood