Unobservable Evidence and Inferential Reasoning

1. Evidence is often “indirect” and reasoning to an object or event is often “inferential” • “Conventional” and common sense view: • Evidence is directly observable • Quarks? Evolution? The Big Bang? • Lederman: evidence for “unobservable” objects • Atoms (for a long time) • Subatomic particles and the “Higgs boson” (today) • Methods • Thought experiments/conceptual analysis (Democritus) • Combination of thought/conceptual analyses and empirical study/evidence

2. Evidence is often “indirect” and reasoning to an object or event is often “inferential” • Justification? • As with Lederman’s invisible soccer ball, such objects or events, or theories that include them, are able to explain what is observable • And often bring together what might otherwise seem like disparate phenomena • Molecules (prior to their being “observed”): • Indirect evidence (expansion, heat conduction, surface tension) • Can be marshaled under the familiar laws of motion

3. Evidence is often “indirect” and reasoning to an object or event is often “inferential” • Gould: evidence for “unobservable” processes • Natural selection (the mechanism) • Evolution (the end result) • Signs of history • Jury rigging and “contrivances” • “Imperfections” • Rudimentary or vestigial organs • Traits as “artifacts” of natural processes (e.g., natural selection)

4. Evidence is often “indirect” and reasoning to an object or event is often “inferential” • Democritus’ thought experiment • Imagine a knife of polished bronze and very sharp. • Begin to cut up a piece of cheese, first in half, then in half again, and so forth, until there are only tiny pieces. • If I were tiny enough to see the pieces and could continue cutting, I would eventually reach something that is not able to be cut, that is indivisible.

5. Evidence is often “indirect” and reasoning to an object or event is often “inferential” • The Big Bang and the Hubble Telescope