Metaphysics is broadly understood as a field of inquiry concerned with the fundamental nature of the world. At its most basic level, it asks questions about what everything is made of, but it has evolved to examine the nature of what exists, including ideas like the properties of material things, the difference between mind and matter, cause and effect, and the nature of existence, being, and reality, a branch known as ontology. While distinct from science in its level of generality and approach, metaphysics is nonetheless concerned with the world, albeit not primarily the part that can be directly observed. Ideally, we might desire a metaphysics that aligns with the world described by science. Peirce places metaphysics as the third and highest branch of philosophy, following logic, and describes it as studying the most general features of reality and real objects. It involves applying the regulative laws of logic to the universe, starting from the assumption that the universe has an explanation to unify observed variety. Ethics, on the other hand, is the division of philosophy concerned with morality, the distinction between good and evil, and how one ought to live. It considers human acts in their bearing on human happiness, their agreement or disagreement with human rational nature, and their relation to one's ultimate end. Ethics also encompasses the study of moral obligation (deontology) and determines duties in detail (natural law). It is considered the most practically important division of philosophy, dealing with practical action and relations with others. According to some phenomenological ethicists, it is concerned with the description of what we do when we behave morally. The interplay between these two fields is complex and debated, as highlighted by various philosophical perspectives in the sources. One perspective suggests that metaphysics can provide a foundation for ethics or at least influence ethical views. The philosophical question of "what should people do in between" birth and death is both scientific and ethical. Sartre notes that while ontology (a branch of metaphysics) cannot directly formulate ethical precepts, as it deals with what _is_ rather than imperatives, it can reveal the origin and nature of value. Value, in his view, arises from the "lack" in human reality, and recognizing this can inform an existential psychoanalysis as a moral description, revealing the ethical meaning of human projects beyond simple self-interest. Aquinas's metaphysics, which starts and ends with God, is seen as crucial to his understanding of being. While moral distinctions can be understood philosophically based on human nature (e.g., certain acts become a man or do not) without immediate reference to God, the ultimate ground of morality rests on the Divine nature, which belongs to the domain of Metaphysics. For Aquinas, theologians consider sin principally as an offense against God, while the moral philosopher sees it as contrary to reason; however, what is contrary to reason offends God and becomes sin. This suggests a hierarchical relationship where the metaphysical understanding of the Divine underpins the philosophical understanding of morality, transforming philosophical obligation into a complete, theological obligation. Peirce's classification of sciences also places metaphysics at a fundamental level relative to ethics. He argues that logic (the theory of how we should reason) presupposes the normative science of ethics, which studies deliberate conduct. Ethics, in turn, presupposes aesthetics (the study of what is most admirable), and aesthetics depends on phenomenology (the contemplation of phenomena as they appear). Metaphysics, following logic, is the first application of logic, concerning the most general features of reality and serving as a basis for special sciences. This structure suggests a dependence chain where phenomenology underpins aesthetics, aesthetics underpins ethics, ethics underpins logic, and logic underpins metaphysics and the special sciences. However, another description places metaphysics as the "third and highest branch of philosophy" after logic, concerning the first application of logic. Regardless of the exact ordering, Peirce sees metaphysics as needing to be grounded in phenomenology and steeped in logic. Stoic philosophy also illustrates a close relationship between its parts: physics (concerned with the cosmos and divine matters), ethics (concerned with human life), and dialectic (concerned with reason and knowledge). Wisdom is defined as knowledge of human and divine matters. There is a debate on whether Stoic ethics can stand alone or must be understood in relation to physics, meaning knowledge of the natural world is indispensable for understanding the good life. According to some Stoic views, one cannot make correct judgments about good and evil without understanding the whole of nature or the life of the gods. This position, where human matters must be understood in relation to divine matters, highlights a dependency of ethics on a metaphysical understanding of the cosmos. Bertrand Russell notes that philosophy exists in a "No Man's Land" between theology and science, addressing questions that science cannot answer and theological answers are no longer universally convincing. These questions include ethical ones about the noble way of living. Historically, ethical beliefs have drawn from political and personal/religious/moral convictions. Furthermore, in later times, philosophy, particularly ethics, became more closely tied to theology, sometimes leading to distinctions that did not fully regard the phenomena of nature or unbiased sentiments. Some contemporary philosophical thought also suggests a blurring or necessary interplay between ethics and fundamental philosophical questions. Levinas's philosophy, for instance, is described as raising ethics to "First Philosophy," starting with the priority of the other. While some interpretations, drawing on Ricoeur, see Levinas's position as "frankly ethical" and "deliberately anti-ontological", his work can also be read as enabling an ethics of Eros and the body by describing the erotic relation as containing intrinsic ethical possibilities, thus linking ethical potential to the nature of encounter and existence. Another perspective suggests that Levinassian metaphysics, which begins with the epistemological exile of God, inverts to a God accessible as a trace in the face of the exiled other and through ethics. This implies that the encounter with the other, understood ethically, can provide access to what might traditionally be seen as metaphysical or theological. Bringing Levinas and Sartre together, their work suggests an ethos grounded in freedom and vulnerability, blurring the line between politics and ethics, and hinting that the encounter with the other is not an affront to transcendence but its possibility. Levinas himself speaks of "resorting" to ethical language to articulate moments of encountering alterity that are irreducible to language or systems of thought, hinting at a "diachrony which cannot be synchronized in representation". Foucault, like Levinas (in some interpretations), also resists traditional metaphysical foundations for ethics. He distinguishes "ethics" as practices of self-formation aimed at becoming a moral kind of being, from a "moral code" which is a set of prescriptions and interdictions. His ethics involves resistance to power/knowledge structures, including those stemming from science. Foucault, along with Habermas, challenges the idea that science encompasses all knowledge, viewing it as a metaphysical claim that prescribes boundaries. They question not just _what is real_ (a metaphysical concern), but the _social function_ of treating something as real, stepping back to a more distanced view rooted in critical theory and genealogy. Foucault specifically sees knowledge as inextricably linked to power, challenging the idea of a discourse solely governed by truth and free from power. His ethical thought, like Lacan's, raises "the question of ethics" as what is difficult, unresolved, and intimately linked to subjectivity and truth, constantly asking what can be _new_ in ethics and involving suspicion of received values. His work does not offer traditional ethical treatises or foundational metaphysics for moral codes. The relationship between metaphysics and ethics is also explored through specific concepts. The concept of "value," which is a measure for distinguishing worth, is theorized both ethically and economically. Ethics uses value to distinguish between ideas like freedom and life when they conflict. Sartre sees ontology as revealing the origin and nature of value as "lack". Hume argues that the moral status of characteristics and actions depends on their consequences (utility), linking normative theorizing with empirical analysis and a causal understanding of consequences. This empirical approach to morality stands in contrast to systems founded on duty or divine will. David Bentley Hart suggests that in a view where existence is contingent on absolute being, ontology and ethics can be seen as one "science," where the desire for being is inseparable from the desire for the good. Phenomenology offers tools to analyze the relationship between empathy and ethics, suggesting that while empathy might not be sufficient for morality, it remains relevant. Phenomenological inquiry should address how relating to others is crucial for intersubjective values and meaningful actions, ultimately engaging with the ethical question. The "and" in "Empathy and Ethics" signifies the essence of their relation, emphasizing that they do not automatically go hand in hand without reflection. Beauvoir, influenced by phenomenology and existentialism, develops an existential ethics based on the ambiguity of the human condition, focusing on the inseparable link between how and why we act. Her work, like Arendt's, centers on the relationship between self, other, and world, viewing the ethical sphere as a space for engagement where our actions and interactions reveal who we are. The debate on the possibility of a philosophical ethics itself touches upon the relationship with metaphysics. Gadamer, in his essay "On the Possibility of a Philosophical Ethics," plays Aristotle against Kant, addressing the "foundation" of ethics. This question of foundation involves the aporia that arises when ethics seeks to become philosophical by reaching the level of reflection on the universal. Gadamer's focus on _phrónesis_ (practical wisdom or reasonableness), as opposed to theoretical knowledge (_epistéme_) or technical skill (_téchne_), emphasizes the practical dimension of ethics and its distinction from purely theoretical or technical domains. His hermeneutics, developing in proximity to practical philosophy, highlights the ethical dimension not in understanding itself, but in the openness to the "beyond" offered by the other. Philosophical theology also illustrates a connection, using philosophical tools (including metaphysics) to investigate theological claims. Questions about theological and scientific realism and their connection are explored in this context. In sum, the relationship between metaphysics and ethics is not one-sided but a dynamic interplay where metaphysical assumptions about reality, existence, and value can influence ethical frameworks, while ethical concerns about human action, values, and the good life can inform or challenge metaphysical views and even the nature of philosophical inquiry itself. Philosophers throughout history have grappled with whether ethics requires a metaphysical foundation, whether it can stand alone, or how it interacts with other domains like science, theology, phenomenology, and politics. The sources reveal a spectrum of views, from those positing a strong dependence of ethics on metaphysics (Aquinas, Stoicism) to those that deliberately distinguish ethics from or even position it in opposition to traditional ontology and metaphysics (Sartre, Levinas, Foucault in certain readings), highlighting the ongoing and complex nature of this relationship.