What are the seven demarcation criteria of science?

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