Study Notes on Falsifiability by Karl Popper

Karl Popper (1902–1994)
- Identified falsifiability as the cornerstone of his philosophy of science.
- Established it as the primary "criterion of demarcation" to distinguish science from nonscience.

A claim, theory, or hypothesis (H) is considered falsifiable if a potentially checkable prediction (O) can be logically deduced from it:
- Logical Relationship: If H → O, then the relationship dictates that if O is observed to be true, H passes the predictive test.
Observational Outcomes:
- If O is true, H is not proven true but passes the test.
- If O is false, H must also be false, as a true statement cannot logically imply a falsehood.

Newton’s Theory
  - Isaac Newton's theory predicts a deviation in Mercury's orbit which does not align with observations. Thus, it is:
    - Falsifiable (empirically vulnerable).
    - Actually falsified (shown to be false).
Einstein's Theory
- Albert Einstein's general theory of relativity can also be subjected to tests:
- It is falsifiable and has passed these tests.
Extraterrestrial Genetic Coding Claim
- The statement "All life in the universe employs the same genetic coding found on Earth" is theoretically falsifiable but not practically testable due to a lack of observed extraterrestrial life.
Non-Falsifiable Claim Example
- The claim "The universe is recreated at each instant by a divine being" does not produce any predictive tests, making it non-falsifiable.

Falsifiability versus Verifiability:
  - Falsifiable: Rules out certain observable situations, allowing a greater empirical content.
  - Verifiable: Empirically verifiable statements logically imply the truth of the claim. Example:
    - "This raven is black" verifies the claim "There are black ravens."

Logical Positivists of the Vienna Circle proposed verifiability as a criterion of demarcation and meaning:
- Claim: A statement is meaningful only if it is verifiable, implying that unverified claims (like metaphysical or ethical) are considered cognitively meaningless.
Popper's Response in Logik der Forschung:
- Rejection of Verifiability: Argues that it excludes significant universal law claims, which cannot be verified due to infinite possible instances.
- Single Negative Instance: A universal claim can be falsified by just one counterexample, e.g., the first black swan disproves "All swans are white".

Popper's vision of science requires claims to take empirical risks:
- A claim must be subject to potential falsification to be considered scientific.
Nonscience includes: Pseudoscience (e.g., Freudian psychology, Marxism) and metaphysics.
Fallibilism: The idea that all scientific theories remain conjectural and open to future revision. There are no certain foundations to knowledge.
Popper's methodology is marked by:
- Conjectures and Refutations: A process of formulating hypotheses not through induction but through testing and falsification.
- Inductive Logic Rejected: He criticized the view that ideas emerge from inductively gathering data.

Scientific Progress through Error: Errors in hypotheses are not detrimental; they are essential for advancement, with the ideology: "We learn from our mistakes."
Popper encourages bold hypotheses that yield novel predictions as they are riskier and easier to evaluate:
- Ad hoc tinkering: Any modifications made solely to save a hypothesis from falsification is regarded as intellectual dishonesty.

Measurement Attempts: Popper aspired to measure degrees of simplicity and empirical content of claims via their degree of falsifiability.

Falsifiability as a Criterion of Science: Many accept it seriously, while others, including scientists, view it as a heuristic rather than a strict rule.
Complex Testing Environments: Often, hypotheses are tested not in isolation but comparatively, as with null hypotheses, complicating singular assertions of falsity.

Historical examples illustrate claims initially considered untestable eventually became significant:
- Comte's Predictions: Claimed elemental composition of the Sun was unknowable until later disproven.
- Pauli's Neutrino: Initially undetectable, yet proved to be a fruitful concept in physics.
Kuhn's Paradigms: Thomas Kuhn argued that Popper's methodology conflicts with historical instances of scientific practice, suggesting that normal scientific work is limited by paradigms that evade serious scrutiny and thus may be unfalsifiable in practice.

Lakatos expanded Popper's methodology, proposing:
- Science should be viewed through competing research programs of theories, rather than isolated hypotheses, as predictive failure does not immediately falsify a research program.