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