falsifications

central question

Can science be demarcated from pseudoscience and importantly can this scientific knowledge be reconstructed without induction? Popper argues that a theory can be scientific but only if the theory makes falsifiable predictions and science advances through bold conjectures and severe tests rather than inductive confirmation

major position

Popper falsificationism - demarcation criterion that holds a theory is scientific if it can forbid certain observations and would be refuted if those observations occurred. Refer to Einstein’s general relativity that predicts light bends near massive objects…the prediction could have been false when we observed light next to the Sun. however, Freudian psychoanalysis can accommodate any possible human behaviour and is therefore unfalsifiable. Corroboration (surviving severe tests) replaces confirmation as the epistemic achievement of science and only suggests that we can rationally continue to use the theory, but it is not proven and we would abandon the theory in favour of a new one if later testing encouraged us to do so

key arg for position

Induction is correctly diagnosed as unable to be justified without circularity or infinite regress; justifying via experience uses the principle being justified. Falsification’s deductive testing method sidesteps this issue completely as predictions are deduced from theories and tested with negative results falsifying the theory without any inductive inference being made. Freud / Einstein contrast as a strong illustration where falsifiability can distinguish productive and genuine science from unfalsifiable pseudo-explanation

major objection

Salmon’s rational prediction objection is decisive. Popper says corroboration statements have no correlative relation to future events and that they are purely backward-looking reports based on past performance. But science routinely uses these corroborated theories to make predictions and expects them to be reliable…either corroboration does in fact have bearing on future events (in which case Popper has smuggled induction back in) OR it does not and science cannot make rational predictions…balloon example illustrates this as the physicist would have no rational basis for his prediction if Popper’s account is correct

what do you think

Popper identifies the problem of induction as a key issue for justifying general truths in science, and his demarcation criterion captures something genuine about what distinguishes science from pseudoscience. But Salmon’s objection is decisive and without induction science loses its capacity for rational prediction. Lakatos is able to provide a methodology of scientific research programmes which preserves Popper’s insights about bold conjectures and novel predictions while giving a more realistic account of how science handles anomalies through the hard core and protective belt distinction

problem of induction

• Inductive inference passes from singular observation statements to universal conclusions

  • ‘This swan is white’ to ‘all swans are white’

  • No matter how many white swans we observe, this cannot logically justify the universal conclusion as any conclusion drawn this way may always turn out false

• Two horns of the problem

  • If we try to justify induction by appeal to experience we face infinite regress of justifying principle of induction based on instances of the success of induction etc.

  • If we try to justify induction deductively by arguing that ‘if induction is justified on many occasions, then it is justified in general…’, this is circular as we are using induction in the first premise to justify induction

  • assigning probability to statements based on inductive inferences can only be justified by invoking another principle of induction…inductive reasoning always causes regress

inductivism / conventionalism

• The obvious response to the problem of induction is inductivism — simply accept induction as the method of science and generalise from observations. But inductivism cannot justify the principle of induction without circularity and has no internal explanation of why scientists choose which facts to investigate or why scientific errors occur so frequently. 

• Conventionalism — the view that theories are frameworks adopted by community agreement — sidesteps the problem but produces a code of honour Lakatos calls dishonourable: with no rigorous principle distinguishing legitimate scientific frameworks from pseudoscience anything can count as good science.

falsification

• Demarcation criterion - a theory is genuinely scientific iff it is falsifiable; it forbids certain possible observations and would be refuted if those observations occurred

  • Einstein’s general relativity predicts that light bends near massive objects, which is a specific prediction that could in principle be false and was tested by eclipse observation…paradigm example disproving Newtonian theory of gravity

  • Freudian psychoanalysis has a justification to explain any possible human behaviour…they make no predictions that could be falsified and as a result they are unfalsifiable and unscientific because they cannot in principle be shown to be wrong…say nothing informative about the world

• Corroboration vs confirmation - Popper says a theory that survives tests without being falsified is not confirmed or verified as this would be inductive reasoning

  • Instead, a theory is corroborated by current testing and evidence - corroboration is purely a report on past performance

  • Science proceeds by bold conjecture and attempted refutation…goal is not to accumulate confirming instances but to expose theories to the most severe tests possible in the hopes of falsifying it and achieving a development

  • A theory that survives tests is preferred because it has not been shown to be false, not because it is true

• Code of honour ( key methodological norm of the framework) is novelty

  • Conjectures should not be ad hoc modifications designed to avoid falsification, but instead ideas that are genuinely new

  • Adding an epicycle to save Ptolemaic astronomy from anomaly is poor science as it does not make any independently testable predictions

  • Einstein’s prediction that light may bend new the sun is good science as it is a bold new claim about the world that goes beyond the evidence motivating it

why certain conjectures?

• Popper struggles to explain why scientists make certain conjectures rather than others… his view is compatible with the social need hypothesis (scientists choose what to study on the basis of social factors) but Popper would hate this implication…if scientists choose what to conjecture based on funding pressures, cultural assumptions and political priorities, the starting point of scientific inquiry is not rationally determined and not objective

• Falsification cannot give a complete account of scientific rationality if he cannot explain where conjectures come from

• RESPONSE - logic of knowledge is separate from psychology of knowledge…how scientists may come up with conjectures is an empirical psychological question and what instead matters for the logic of science is how theories are tested… the act of inventing a theory involves creative intuition and therefore outside the logic of science entirely - this does not threaten the logical structure of falsification as the conjecture (whether irrational or social) can be tested

  • But if there is no rational account of conjecture generation and they are influenced via social factors, he cannot explain the entire process of scientific progress with reason and the line between science and pseudo-science is slightly blurred

Duhem-Quine objection

• Popper requires that a negative test result definitively falsifies a theory…but as Duhem and Quine showed, theories face a tribunal of experience not individually but as a web…when a prediction fails, how can we know which part of the web to falsify?

• Take an experiment like boiling water - if the thermometer reads 99 degrees rather than 100, why should we conclude the hypo of boiling point is false when it could be that the thermometer is inaccurate, the altitude is affecting the result, impurities are present or the room pressure is different…these auxiliary assumptions could be revised instead of the core theory

• Scientists can always save a theory from complete falsification by modifying auxiliary hypotheses rather than the core claim…so under this, adding epicycles or slightly tweaking Newton’s theory is allowed

• RESPONSE - ad hoc modifications are methodologically illegitimate… they do not have the novelty that is part of the code of honour

  • But then what counts as a legitimate auxiliary adjustment vs an illegitimate ad hoc modification? This happens all the time; Neptune was discovered via a postulation of an unobserved planet to save Newton’s laws when they predicted Uranus’ orbit wrong…this looked like a legitimate auxiliary adjustment since it made a specific prediction about where to look with testable predictions, but the same logical structure could be used to postpone falsification of a false theory…

• This is more of an issue than conjecture obj bc it strikes at core of what falsification requires

salmon’s rational prediction objection

• Popper claims that corroboration (surviving severe testing) provides a rational basis for preferring one theory over another for practical prediction..but Popper also explicitly says corroboration statements have no bearing on future events and they are purely based on past performance / say nothing about future performance

• This creates a tension illustrated by the balloon example…the friendly physicist predicts the balloon will move forward when the plane accelerates…his prediction is based on physical theory corroborated by past tests…when he wins the bet, what rational basis did he have for making the prediction on Popper’s account?

• If corroboration has no bearing on future events preferring a well-corroborated theory gives no rational grounds for expecting it to perform well in the future

• Salmon’s dilemma - either Popper’s science embodies essential inductive aspects (past testing performance is a guide to future reliability) or science on Popper’s account lacks genuine predictive content

• RESPONSE - we should prefer best tested theory because there is nothing more rational than well-conducted critical discussion

  • Reply - question-begging as saying the best tested theory is the most rational choice for prediction assumes that past testing performance is a guide to future predictive success, which is the inductive assumption Popper claims to have eliminated

  • If corroboration has no relevance to future predictions then preferring the best tested theory for practical action is no more rational than flipping a coin

• Implication - Popper’s position may ultimately rest on a covert commitment to scientific realism (belief that the world has regularities making past testing performance a reliable guide to future behaviour); so Popper’s rejection of induction depends on a metaphysical assumption he has not justified and his epistemology is not as far from inductivism as claimed

lakatos account

• Lakatos offers a more sophisticated alternative - Lakatos replaces individual theory falsification with the evaluation of research programmes over time - distinguishing protected hard core of central commitments from a belt of auxiliary hypos that absorbs anomalies

  • What makes a programme progressive is when auxiliary modifications generate novel independently testable predictions that are subsequently confirmed

  • It is degenerative when modifications are ad hod and accommodate anomalies without predicting something new (this answers Duhem-Quine by accepting that individual falsification is impossible while preserving a criterion for evaluating theories)

  • It answers Popper’s problems because postulating Neptune was a progressive modification means it generated a novel prediction that was confirmed…saying Newtons laws work differently near uranus for unknown reasons would be degenerative; overall this provides a distinction between legitimate auxiliary adjustments and illegitimate ad hoc moves