Definition
Testability (falsifiability) is a necessary but not sufficient criterion for scientific status. What ultimately distinguishes science is the pursuit of good explanations — theories that are hard to vary — of which testability is just one dimension.
Why It Matters
Testability is just a ‘sniff test.’ The real goal of science is ‘good explanations’—theories that are hard to vary. Focusing on explanation prevents ‘cargo cult science’ and ensures that our knowledge is grounded in deep, structural truths rather than lucky guesses.
Core Concepts
- Popper’s demarcation criterion: A theory is scientific if and only if it is falsifiable — it makes predictions that could be shown false by observation. This was a major advance over verificationism.
- Why testability is not enough: Testable predictions are easy to generate. A prophet says ‘there will be a war within a decade’ — testable and usually true. A gambler says ‘this horse will win’ — testable. Neither constitutes science.
- The conjuring trick analogy: Imagine a conjuror performs a trick and you correctly predict it. Does predicting the trick explain how it works? No. Prediction and explanation are distinct. Science requires explanation, not merely prediction.
- The ‘hard to vary’ criterion is primary: A good scientific explanation is one where every component plays a necessary role — changing any detail would break the explanation. Testability is a consequence of this hardness-to-vary, not the defining feature.
- Reach as supplementary criterion: Good explanations also have excess reach — they explain more than they were designed to. This further distinguishes them from mere predictive rules tuned to specific observations.
- Untestable good explanations: Some good explanations are not currently testable (e.g. the multiverse, some historical claims) but are still scientifically valuable because they are the best hard-to-vary explanations available. Their testability may increase as technology improves.
- Testable bad explanations: ‘The weather is controlled by angry gods’ is testable (pray and see). But it’s a bad explanation — easy to vary (which god? how angry?).