{"id": "card_theory_formal_logic_epistemology", "kind": "reference", "title": "Formal logic & epistemology (validity, inference)", "body": "Formal logic & epistemology (validity, inference) — an engine domain that can touch it: philosophy. Calibration: map-only — validity checks compute; epistemology is interpretive. VALIDITY and TRUTH are different properties, and confusing them is the most consequential error in reasoning. A valid argument guarantees that IF the premises are true the conclusion must be; it says nothing about whether they are. An argument is SOUND only when it is valid AND its premises are true. Perfectly valid reasoning from false premises produces confident nonsense.\n\nTHREE KINDS OF INFERENCE, and only one is certain. DEDUCTION preserves truth and adds no information. INDUCTION generalises from cases and can always fail — Hume's problem, still unsolved. ABDUCTION infers the best available explanation and is what diagnosis, detective work and most science actually use, while being the weakest of the three.\n\nKNOWLEDGE was long defined as justified true belief until Gettier (1963) produced cases satisfying all three that nobody would call knowledge. Fifty years of proposed repairs have not settled it. This project's own posture follows from that: state the warrant, distinguish CONFIRMED from PLAUSIBLE from RESONANCE, and never let a valid-looking chain substitute for a checked premise.", "source": {"label": "The Theory Assay — calibrated, not judged (docs/THEORY_CATALOG.md)", "url": "", "domain": "philosophy", "authority_tier": "reference"}, "shelf": "theories", "box": "theory", "bands": ["theory", "philosophy", "seals", "calibration", "humanities", "witness"], "subject": "Formal logic & epistemology", "connections": [{"to_card_id": "card_spine_theories", "relationship": "member_of", "evidence": "a theory the sciences and math run on, calibrated"}], "author": "engine", "created_at": 0.0, "updated_at": 0.0, "visibility": "public", "lifecycle_stage": "public", "volatility": "permanent", "surface": "secular", "generated": false, "extra": {"calibration": "seals", "engine_domain": "philosophy", "section": "Humanities & witness"}, "call": "theories.theory", "facets": {"subject": ["calibration", "humanities", "philosophy", "seals", "witness"]}, "presentation": {"glyph": "•", "kind_label": "theory", "by": "The Theory Assay — calibrated, not judged (docs/THEORY_CATALOG.md)", "authority": "reference", "posted": "", "standing": ""}, "neighbors": [{"id": "card_spine_theories", "title": "The theories the sciences and math run on", "relationship": "on the shelf of", "why": "a theory the sciences and math run on, calibrated", "href": "/card/card_spine_theories", "resolved": true}], "house": {"door": "FIND", "kind": "card", "trail": "connections", "seal": "/card/card_theory_formal_logic_epistemology", "next_step": {"do": "follow a connection: what this card rests on, and what rests on it", "door": "FIND", "tool": "card_connections", "params": {"id": "card_theory_formal_logic_epistemology"}}, "ends": "a verdict or a card · the trail · a seal · one next step"}}