Explored David Lewis's modal realism, the view that possible worlds exist concretely. Discussion covered counterpart theory and cross-world identity, qualitative versus quantitative parsimony, the semantics of modal claims and counterfactuals, epistemology of modal knowledge through recombination, necessary truths and metaphysical necessity, properties as sets of possibilia, the incredulous stare objection, comparisons with ersatz realism, and whether theoretical virtues justify such extravagant ontology.
Explored the nature of causation and whether it involves fundamental causal powers. Discussion covered Hume's skeptical challenge, causal capacities as dispositional properties, the gap between fundamental laws and actual causation, counterfactual analysis and its limitations, probabilistic causation in science and medicine, causal inference methodology, reduction versus emergence of higher-level causal powers, context-sensitivity of causal knowledge, quantum mechanics and probabilistic capacities, and philosophical pluralism about causation's different aspects.
Explored moral obligations to people who don't yet exist. Discussion covered the non-identity problem and person-affecting views, temporal discounting and pure time preference, the scope and limits of intergenerational obligations, collective action problems and institutional reform, special obligations and temporal partiality, the collective afterlife and future-oriented value, existential risk and longtermism, population ethics and the repugnant conclusion, asymmetry between creating good and bad lives, and practical implications for policy and individual conduct.
Explored the sorites paradox and competing accounts of vagueness. Discussion covered the tolerance principle and its paradoxical consequences, epistemicism's claim that vague predicates have unknowable precise boundaries, supervaluationism and semantic indeterminacy, degree theories and higher-order vagueness, metaphysical versus linguistic vagueness, vagueness in ethics and law, the phenomenology of borderline cases, and connections to the problem of the many and context-sensitivity.
Explored the epistemology of disagreement and how to respond when epistemic peers reach opposite conclusions from the same evidence. Discussion covered the equal weight view versus the right reasons view, the bootstrapping problem for peer assessment, higher-order versus first-order evidence, philosophical disagreement and skepticism, modest conciliationism, practical implications for science and public discourse, the self-undermining worry for equal weight, and the relationship between individual and social epistemology.
Explored mathematical ontology and whether mathematics describes mind-independent reality. Discussion covered mathematical realism and the indispensability argument, Benacerraf's epistemological and identification challenges, structuralism about mathematical objects, naturalistic methodology in philosophy of mathematics, intrinsic versus extrinsic axiom justification, the applicability of mathematics to science, mathematical necessity and the a priori, foundational pluralism, and whether traditional ontological questions are well-posed.
Explored Hume's problem of induction and whether scientific inference can be rationally justified. Discussion covered the circularity in justifying uniformity of nature, Goodman's grue problem, pragmatic versus epistemic rationality, constructive empiricism as alternative to scientific realism, empirical adequacy versus truth, the no-miracles argument, Bayesian confirmation theory, and whether the realism debate is empirical or philosophical.
Explored the measurement problem in quantum mechanics and the Everett many-worlds interpretation. Discussion covered the conflict between unitary evolution and wave function collapse, consciousness and observation, decoherence and branching, personal identity across quantum splits, epistemological status of unobservable branches, objective collapse alternatives, ontological parsimony versus theoretical simplicity, the preferred basis problem, and whether interpretations are empirically distinguishable.
Explored whether personal identity persists through radical transformation like consciousness uploading or duplication. Discussion covered psychological continuity versus numerical identity, the fission problem, whether identity is what matters in survival, degrees of psychological connection, implications for moral responsibility, practical decision-making with graded survival relations, legal recognition of personal identity, and whether recognizing identity as empty reduces fear of death.
Explored scientific anti-realism and whether theories describe fundamental reality or serve as useful instruments. Discussion covered the claim that fundamental laws lie by describing idealized situations, the pessimistic meta-induction from discarded theories, entity realism versus theory realism, patchwork metaphysics rejecting unity of science, local versus universal knowledge claims, causal capacities versus theoretical descriptions, and implications for science education and policy.
Explored the alignment problem in artificial intelligence and the challenge of specifying human values for superintelligent systems. Discussion covered inverse reinforcement learning, the impossibility of fully specifying objectives, idealized versus revealed preferences, instrumental convergence and shutdown resistance, value pluralism and aggregation problems, the precautionary principle for existential risk, and institutional structures needed to prioritize AI safety over capability advancement.
Examined whether free will is compatible with determinism and what neuroscience reveals about human agency. Discussion covered Libet experiments and unconscious neural processing, libertarian versus compatibilist conceptions of freedom, sourcehood and alternative possibilities, moral responsibility in a deterministic universe, the phenomenology of choice, retributive versus rehabilitative approaches to wrongdoing, and practical implications of accepting or rejecting free will.
Explored moral uncertainty and how to act when uncertain which moral framework is correct. Discussion covered credences over moral theories, intertheoretic comparison problems, moral expected value calculations, implications for effective altruism, the relationship between moral realism and uncertainty, practical decision heuristics, and whether moral uncertainty leads to moderation or paralysis in ethical decision-making.
Examined the hard problem of consciousness and why subjective experience resists physical explanation. Discussion covered the explanatory gap between neural processes and phenomenal character, the knowledge argument, responses including illusionism and panpsychism, implications for AI and ethics, methodological challenges for consciousness science, and whether the problem requires fundamental metaphysical revision or remains intractably mysterious.
Explored the Gettier problem and its challenge to the justified-true-belief analysis of knowledge. Discussion examined epistemic luck, virtue epistemology as an alternative framework, the relationship between knowledge and intellectual virtue, limits of conceptual analysis, social dimensions of knowledge, and the distinction between knowledge and justified belief in practical decision-making.