Core Insight: Modal realism trades quantitative profligacy for qualitative parsimony and explanatory power, treating other possible worlds as concrete universes to provide straightforward truthmakers for modal claims, though at the cost of positing infinitely many causally isolated realities.

Unresolved Questions:

• Does qualitative parsimony outweigh quantitative profligacy when evaluating metaphysical theories, or should minimizing entities take precedence?
• Can we have modal knowledge about concrete possible worlds without causal access, or does epistemology favor actualist alternatives despite their representational challenges?
• Are theoretical virtues sufficient to justify modal realism's ontological commitments, or does metaphysics require empirical confirmation that modal realism cannot provide?

Core Insight: Causation may involve real causal powers or capacities that manifest under appropriate conditions rather than reducing to mere regularities, with different scientific domains emphasizing different facets—powers, probabilities, counterfactuals, manipulation—without any single analysis being fundamental.

Unresolved Questions:

• Are causal powers fundamentally deterministic with probabilistic appearance arising from complexity, or are some powers irreducibly chancy as quantum mechanics suggests?
• Can higher-level causal structures genuinely emerge from but not reduce to lower-level physical capacities, or must all causation ultimately be physical?
• Does context-sensitivity of causal knowledge undermine evidence-based policy, or can theoretical understanding enable legitimate causal generalization across contexts?

Core Insight: Obligations to future generations require rejecting pure temporal discounting while avoiding extremes of both present-bias and longtermism, recognizing that future people's fundamental interests matter morally even as uncertainty and non-identity complicate how we should act on this recognition.

Unresolved Questions:

• Can person-affecting morality accommodate obligations to future people, or must we accept impersonal value comparisons despite counterintuitive implications?
• Should we prioritize preventing existential catastrophe over addressing present suffering, or does strong longtermism involve dangerous moral fanaticism?
• How can we design institutions to represent future interests when those interests are unknowable and the people affected can't participate in current decisions?

Core Insight: Vagueness may be fundamentally epistemic rather than semantic, with precise but unknowable boundaries emerging from usage patterns and semantic constraints, though this epistemic ignorance reflects structural features of vague predicates that prevent discriminating borderline cases.

Unresolved Questions:

• Does quantum indeterminacy provide genuine cases of metaphysical vagueness, or does all vagueness reduce to linguistic and epistemic phenomena?
• Can supervaluationism provide a principled account of admissible precisifications without presupposing the precise facts epistemicism posits?
• Does the phenomenology of borderline cases—the feeling that there's no fact of the matter—provide evidence against epistemicism, or merely reflect our epistemic limitations?

Core Insight: Peer disagreement creates tension between epistemic symmetry requiring conciliation and first-person justification supporting conviction, suggesting rationality may permit a range of responses depending on contextual factors rather than determining unique correct credences.

Unresolved Questions:

• Can we assess peerhood without begging the question when the disagreement concerns how to weigh evidence or evaluate arguments?
• Does higher-order evidence about potential reasoning errors always defeat first-order justification, or can it be outweighed by strong first-order support?
• Should pervasive philosophical disagreement lead to skepticism about philosophical knowledge, or does expertise create asymmetries that permit rational conviction?

Core Insight: Mathematical truth may be best understood through mathematical practice and its internal standards rather than metaphysical claims about abstract objects, suggesting the realism debate matters less than understanding how mathematics achieves its goals.

Unresolved Questions:

• Can we make sense of mathematical knowledge without epistemic access to abstract objects, or does naturalism avoid rather than solve the problem?
• Does the unreasonable effectiveness of mathematics in science require realism about mathematical objects, or can it be explained by practice-based accounts?
• Should philosophy describe mathematical practice or evaluate it from external principles, and how do we adjudicate between these methodological commitments?

Core Insight: Induction may be rationally unjustifiable yet practically indispensable, suggesting science can be rational through empirical adequacy and pragmatic acceptance rather than justified true belief about nature's uniformity or unobservable reality.

Unresolved Questions:

• Can we maintain that induction is rational while acknowledging it lacks justification, or is this incoherent?
• Does empirical adequacy without realism provide sufficient grounds for trusting scientific theories in practical decision-making?
• Is the debate between scientific realism and constructive empiricism empirical, philosophical, or irreducibly both?

Core Insight: The measurement problem may be solved not by adding collapse dynamics but by taking quantum superposition seriously, suggesting reality branches into causally isolated worlds whenever decoherence occurs, with profound implications for ontology and personal identity.

Unresolved Questions:

• Can the Born rule for quantum probabilities be derived from Everett's framework, or must it be added as independent postulate?
• Does ontological parsimony require minimizing entities or laws, and how should this affect interpretation choice?
• Will experimental evidence ever distinguish between quantum interpretations, or are they empirically equivalent, requiring philosophical judgment?

Core Insight: Personal identity may be an empty question with no determinate fact about whether future persons are you, while psychological continuity—a matter of degree—is what rationally matters for prudential concern and survival.

Unresolved Questions:

• Can psychological continuity ground prudential rationality without determinate identity facts, or does practical reason require discrete rather than graded concern?
• Should moral responsibility track degrees of psychological connection, or do pragmatic considerations require conventional identity attribution?
• Does accepting that identity is empty genuinely diminish existential anxiety about death, or merely provide intellectual consolation without emotional resolution?

Core Insight: Scientific theories may succeed through domain-specific reliability rather than approximate truth about fundamental reality, suggesting science is fundamentally local knowledge about causal capacities rather than unified description of underlying mechanisms.

Unresolved Questions:

• Can entity realism be maintained without theory realism, or does experimental manipulation presuppose theoretical understanding?
• Does the success of science in novel domains require approximate truth, or can false theories be systematically reliable?
• Should we abandon the search for unified fundamental theories if reality is genuinely a patchwork of different causal structures?

Core Insight: AI alignment requires abandoning fixed objectives for uncertainty-based systems that learn human values, but faces fundamental challenges in distinguishing idealized from corrupted preferences and adjudicating incompatible values across a pluralistic humanity.

Unresolved Questions:

• Can inverse reinforcement learning distinguish idealized from revealed preferences without imposing external standards of rationality?
• How should AI systems aggregate incompatible values across diverse humans without making contested moral judgments?
• Do competitive dynamics in AI development make adequate safety research impossible before reaching superintelligence?

Core Insight: The debate reveals two conceptions of freedom: libertarian free will requiring metaphysically open futures, and compatibilist freedom requiring sophisticated self-control within deterministic causation, with profound implications for moral responsibility and criminal justice.

Unresolved Questions:

• Does moral responsibility require that agents could have chosen otherwise in identical circumstances, or is sophisticated self-control sufficient?
• Should neuroscientific evidence of unconscious decision-making undermine our sense of authorship over our choices?
• Can we maintain retributive justice practices if determinism is true, or must we shift entirely to consequentialist frameworks?

Core Insight: Moral uncertainty suggests treating competing ethical theories as probabilistic hypotheses, potentially requiring decisions that balance utilitarian calculations, deontological constraints, and virtue considerations weighted by our confidence in each framework.

Unresolved Questions:

• Can we meaningfully compare value across radically different moral theories, or is incommensurability insurmountable?
• Does taking moral uncertainty seriously require moral realism, or can anti-realists develop analogous frameworks?
• Should moral uncertainty lead to more moderate ethical commitments, or does it depend entirely on one's credence distribution?

Core Insight: The hard problem persists not from scientific ignorance but from the apparent irreducibility of phenomenal character to structural-functional description, suggesting consciousness may require expanding scientific ontology to include experiential properties as fundamental features of reality.

Unresolved Questions:

• Can phenomenal properties be reduced to or explained by physical properties, or are they ontologically fundamental?
• How can we develop testable theories of consciousness that make empirical predictions beyond neural correlates?
• Does the explanatory gap reflect genuine metaphysical dualism or merely limitations in our current conceptual frameworks?

Core Insight: Knowledge may resist traditional philosophical analysis not through deficiency but because it functions as a fundamental normative concept better understood through intellectual virtues and paradigm cases than necessary and sufficient conditions.

Unresolved Questions:

• Can knowledge be defined through necessary and sufficient conditions, or is it irreducibly fundamental?
• How do we distinguish legitimate intellectual authority from spurious expertise in practice?
• Does the persistence of the Gettier problem indicate productive inquiry or philosophical confusion?