Green River Cliffs, Wyoming | Thomas Moran, 1881
Key Terms for this Section
Divine Command Theory · Natural Law Theory · Aquinas’ Seven Basic Goods
Conservation · Sustainability · Biodiversity
3.1 | Natural Law Theory
Central Question: Can morality be grounded in the natural world?
Divine Command
For much of human history, moral authority has been closely associated with religious belief. In the major Western religious traditions — Judaism, Christianity, and Islam — moral obligations are often presented as expressions of divine will. This association raises a foundational philosophical problem: whether moral rightness depends entirely on what God commands, or whether moral truth exists independently of divine decree.
This problem is classically articulated in Plato’s dialogue Euthyphro, where Socrates asks whether actions are good because God commands them, or whether God commands them because they are good. The dilemma reveals a tension within early Ethics. If God commands actions because they are already good, then goodness must exist independently of divine will. In that case, divine authority does not create moral truth but merely recognizes it.
The alternative position claims that actions are morally right simply because God commands them. This view is known as Divine Command Theory, the view that moral rightness is determined solely by God’s commands, such that an action is morally right solely because God commands it. At first glance, this approach appears to preserve divine authority. However, it introduces some philosophical difficulties for the careful observer. For example, if morality rests entirely on divine command, then moral rules seem to be arbitrary. Any action — no matter how cruel or unjust to us — would become morally right if commanded by one’s interpretation of scripture. Now, while many religious communities are kind and generous with their interpretation (including my own religious community), others bring great harm into the world in the name of religion.
Additional problems arise, as different religious traditions appeal to different scriptures, and even within a single tradition, there are persistent disagreements about a text’s proper meaning and application. So, follow this — if moral obligation depends entirely on divine command, our interpretation should be moot. Yet our subjective interpretation of sacred text is required, as no text interprets itself — and interpretation requires human reasoning.
So we find ourselves right back where we started. Our discussion of ethics will always require us to use reason to interpret laws, scripture, and social situations for their moral importance. Divine Command Theory, without further work, struggles to explain how moral truth can be both authoritative and rationally accessible.
Natural Law Theory
In the 1200s, Natural Law Theory emerged as a response to the philosophical problems raised by Divine Command Theory.
Rather than grounding morality in divine commands alone, this approach locates moral truth in the rational structure of reality itself. According to this view, the world is not morally neutral. Rather, the world possesses an intelligible order that reflects the purpose, value, and normativity of its Creator.
This position is articulated most clearly in the work of St. Thomas Aquinas, who understands God as both Creator and Lawgiver. Because God creates a rational world (according to Catholic doctrine) and declares it good, moral order must be embedded within the creation itself. Moral truths are not arbitrary decrees imposed from outside reality; rather, they arise from the way reality itself is structured. As a result, moral knowledge does not require special revelation. It can be discovered through rational reflection on human nature and the conditions necessary for flourishing.
This approach is known as Natural Law Theory, the view that moral truths are grounded in the rational structure of reality itself and can be discovered through human reason. Moral obligations arise not from blind obedience to command but from rational recognition. Human beings, as rational moral agents, are capable of discerning which actions align with their nature and which undermine it.
Aquinas defines law as “an ordinance of reason for the common good, made by one who has care of the community.” This definition emphasizes that genuine law must be rational (not arbitrary), ordered toward the common good (not merely for private interest), and conducive to the flourishing of the community. Laws that fail to meet these criteria may be enforced, but they lack moral authority.
Because Natural Law appeals to reason rather than revelation alone, it can function within pluralistic societies like ours.
Moral truths are accessible to all rational agents, regardless of religious belief. One need not accept theological premises to recognize that certain practices undermine life, social cooperation, or human dignity. Moral reasoning begins with reflection on what it means to be human in an ordered world.
Natural Law & Moral Objectivity
Natural Law Theory directly addresses the Grounding Problem introduced in Section 2. If moral truths are objective, they must be grounded in something more stable than personal feeling, cultural convention, or arbitrary authority. Natural Law claims that moral facts are grounded in the rational order of reality itself. This grounding explains why moral truths bind human agents even when they are ignored, denied, or violated.
Because moral norms arise from human nature and the conditions of flourishing, they are universal rather than relative. Practices such as slavery, segregation, or systemic cruelty are unjust not because societies disapprove of them, but because they contradict objective goods required for human dignity and social life. This explains how moral criticism across cultures and historical periods (ie. Moral Objectivism) is possible.
A clear historical example of Natural Law reasoning appears in Martin Luther King Jr.’s Letter from Birmingham Jail. Dr. King distinguishes between just and unjust laws, arguing that unjust laws are not true laws at all. Laws that degrade human dignity or undermine community fail to meet the standards of reason and the common good. His argument does not rely on sectarian authority. It appeals to moral principles accessible to all rational agents.
Natural Law Theory thus offers a robust account of moral objectivity without collapsing into relativism or Appeals to Authority. Moral truth is not contingent on belief, enforcement, or consensus. It can be discovered, debated, misunderstood, and corrected through rational inquiry. Ethical disagreement remains meaningful because there is something objective at stake.
(For our course, I recommend watching the video below of MLK from 16:42 - 19:08.)
Optional Video: Martin Luther King Junior reads his letters form Birmingham Jail (auto-generated CC).
3.2 | St. Aquinas’ Seven Basic Goods
Central Question: What moral goods might we derive from nature?
Human Nature & Moral Teleology
Natural Law Theory claims that moral truths are grounded in the structure of reality and accessible through reason.
To understand how this works in practice, it is necessary to clarify what Natural Law assumes about human beings themselves. For St. Aquinas, morality cannot be separated from human nature. Ethical reasoning begins with an account of what kind of beings humans are and what conditions allow them to flourish.
As moral agents, we human beings are rational, social, and embodied creatures.
We are not merely biological organisms driven by instinct, nor are we disembodied minds detached from the world. Human life unfolds within physical, social, and intellectual contexts that shape moral responsibility. Because humans possess reason, they are capable of reflecting on their actions, evaluating ends, and directing their lives toward intelligible goals. Moral agency, on this view, is inseparable from rational self-direction.
This orientation toward ends is known as teleology (more on teleology in Section 4). To say that humans have a nature is to say that certain ways of living are more consistent with that nature than others. Just as the function of the eye is to see and the function of the heart is to circulate blood, human beings have characteristic ends that define what it means to live well. Moral reasoning, therefore, is not arbitrary. It involves discerning which actions align with these ends and which frustrate them.
For Aquinas, flourishing is not a matter of preference or cultural fashion. It refers to the fulfillment of capacities that belong to us as human beings. While cultures differ in how they express values, the underlying goods that support human life remain constant. Natural Law does not deny moral complexity or disagreement, but it insists that such disagreement presupposes shared goods that make evaluation possible at all.
This account avoids two common mistakes. First, Natural Law rejects moral relativism, which treats values as inventions of culture or feeling, and it avoids rigid legalism, which reduces ethics to mere rule-following. Instead, Natural Law sees morality as a rational response to the goods that nature (including our own nature) makes possible. To act well is to act in ways that realize those goods coherently and sustainably.
Understanding St. Aquinas’ Seven Basic Goods
In his philosophical efforts, Aquinas identifies a set of objective goods toward which human beings are naturally inclined. These are known as the Seven Basic Goods, the fundamental and objective goods (listed below) rooted in human nature that define the conditions necessary for genuine human flourishing. Aquinas claims these goods are not derived from social convention, religious command, or personal desire. They are recognized through reflection on what humans, as rational beings, necessarily seek to live full, meaningful lives.
The first good is life. This includes not only survival but health, bodily integrity, and the basic conditions that make any form of action possible. The preservation of life is foundational because every other good presupposes it. Actions that arbitrarily destroy or degrade life contradict this most basic orientation of human nature.
The second good is reproduction. Aquinas understands reproduction not merely as biological procreation, but as participation in the continuation of the human community. This good reflects the intergenerational structure of human life and the responsibility to sustain the conditions under which humanity endures.
Closely connected to this is the good of educating one’s offspring. Children require long-term care, instruction, and moral formation. Education, in this sense, includes intellectual, moral, and social development. Without it, neither individuals nor societies can flourish.
Another basic good is living in society. Human beings are not self-sufficient. Friendship, cooperation, trust, and political organization are necessary for stable and meaningful lives. This good grounds duties of justice, fairness, and mutual respect, and it explains why actions that undermine social cohesion are morally significant.
Aquinas also identifies pursuing knowledge as a basic good. Humans possess a natural desire to understand the world, themselves, and their place within it. The pursuit of truth through science, philosophy, and art fulfills this rational appetite and distinguishes human life from mere survival.
Avoiding offense refers to the good of moral integrity and social harmony. This good encompasses honesty, reputation, and respect for others. Actions that generate scandal, unnecessary conflict, or humiliation damage the trust on which social life depends.
Finally, Aquinas includes seeking God as a basic good. Even apart from specific religious commitments, this good reflects the human inclination toward ultimate meaning and transcendence. It accounts for the widespread human concern with purpose, origin, and destiny, expressed through philosophy, religion, and cultures across our planet.
Moral Failure & the Frustration of Goods
Understanding the Seven Basic Goods provides a framework for evaluating moral success and failure. On Aquinas’ account, immoral actions are not merely prohibited by rule or condemned by authority. Rather, moral wrongs are defective because they frustrate goods that human beings necessarily depend upon for flourishing. Moral failure is thus intelligible rather than mysterious.
An action may appear beneficial in the short term while undermining deeper goods. For example, deception may offer immediate advantage, but it corrodes trust and damages social cooperation. Exploitation may produce economic gain, but it undermines justice and community stability. Such actions are not wrong because they violate convention; they are wrong because they contradict the goods that make human life meaningful and sustainable.
This framework also applies beyond individual behavior to institutions and laws. A legal system that suppresses education, undermines family life, or restricts the pursuit of knowledge may function efficiently while remaining morally unjust. From a Natural Law perspective, institutions are evaluated by whether they support or obstruct the basic goods that constitute human flourishing.
Importantly, Aquinas’s account explains moral disagreement without collapsing into relativism. People may disagree about how best to realize the goods, or how to balance them in complex circumstances. Such disagreement presupposes shared recognition of the goods themselves. Moral reasoning remains possible because there is a common standard against which actions can be assessed.
The Seven Basic Goods also prepare the ground for applied ethics. Environmental practices, economic systems, and political policies matter morally insofar as they affect the conditions under which these goods can be realized. Human flourishing does not occur in abstraction. It depends on material, social, and ecological contexts that either support or undermine the goods Natural Law identifies.
The next lessons in Section 3 extend Natural Law reasoning to the natural environment, examining how land, resources, and ecosystems become morally relevant once human flourishing is understood as embedded in the world that sustains it.
3.3 | Natural Law & the Environment
Central Question: Does human flourishing create moral duties to nature?
Natural Law & the Environment
Natural Law Theory grounds morality in the rational structure of reality and locates ethical obligation in the conditions necessary for human flourishing. Because human beings are embodied, social, and materially dependent, this framework carries clear implications for how the natural environment must be understood morally. If the goods necessary for flourishing arise from human nature itself, then the environmental conditions that sustain human life cannot be ethically neutral.
Human beings do not exist apart from nature.
Food production, shelter, medicine, education, and social cooperation all presuppose reliable access to land, water, energy, and ecological systems. From a Natural Law perspective, these dependencies are not accidental. They reflect stable features of human life that any rational moral framework must acknowledge. Environmental degradation, therefore, affects morality indirectly but decisively by undermining the material conditions through which basic human goods are realized.
This reasoning challenges the assumption that nature is morally irrelevant simply because it lacks agency. Forests, rivers, and wildlife are not moral agents, but they are morally significant insofar as they support human flourishing. When environmental systems are damaged or exhausted, the ability of individuals and communities to pursue health, security, knowledge, and social stability is compromised. Actions that predictably undermine these conditions conflict with the rational orientation toward the good that Natural Law requires.
Natural Law also rejects purely instrumental views of the environment that treat land and resources as limitless commodities. Rational moral agency involves foresight, planning, and restraint. Because human beings can anticipate the long-term consequences of their actions, they bear responsibility not only for immediate outcomes but also for how present choices shape future conditions for flourishing.
Conservation & the Common Good
Within this framework, environmental responsibility is best understood through Conservation, the rational management of natural resources so that their availability and integrity are preserved over time. Conservation does not oppose agriculture, industry, or development. Instead, it aligns human activity with the long-term requirements of human life identified by Natural Law.
From a Natural Law perspective, conservation is an expression of the common good.
Natural resources support shared human needs rather than isolated private interests. Soil fertility, clean water, and stable ecosystems benefit entire communities and future populations. Practices that exhaust or contaminate these resources for short-term advantage violate the rational obligation to preserve the conditions that allow others to flourish as well.
East Texas provides a clear illustration of this reasoning. Agricultural, ranching, and forestry traditions in the region depend on responsible land management. Practices such as crop rotation, rotational grazing, selective harvesting, and reforestation reflect an implicit recognition that productivity requires restraint. These methods preserve soil health, reduce erosion, and maintain water quality, ensuring that land remains usable across generations. From a Natural Law standpoint, such practices are morally justified because they protect the material conditions necessary for ongoing human goods.
Conservation also supports economic stability when evaluated rationally over time. Unsustainable practices may generate immediate profit, but they impose long-term costs through depleted aquifers, eroded soil, and degraded forests. These costs are borne not only by individual landowners but by entire communities. Conservation therefore reflects rational coordination between economic activity and moral responsibility rather than opposition between the two.
Video explaining selective harvesting (auto-generated CC).
Conservation, Law, & Moral Responsibility
Natural Law distinguishes between laws that merely regulate behavior and laws that possess genuine moral authority. Environmental laws fall into the latter category when they are grounded in reason and oriented toward the common good. Regulations that protect water quality, forest health, or wildlife habitats are morally defensible when they preserve the material conditions necessary for human life and social stability.
This framework also introduces an intergenerational dimension to moral responsibility. Future persons are not abstract entities; they will require food, water, shelter, education, and social institutions just as present populations do. Actions that irreversibly damage ecosystems compromise the ability of future communities to realize basic goods. Conservation therefore reflects rational concern for moral continuity across time rather than sentimental concern for nature itself.
Natural Law avoids framing environmental ethics as a conflict between human needs and ecological concern. Human flourishing depends on ecological integrity, and short-term exploitation undermines the shared goods upon which society relies. Moral responsibility involves restraining such exploitation in light of foreseeable consequences, proportionality, and necessity.
At the same time, Natural Law sets clear limits on environmental obligation. Conservation does not require treating nature as sacred or as morally equal to human life. It merely requires recognizing natural resources as morally significant supports of human flourishing. Ethical evaluation therefore focuses on reasoned judgment rather than absolute preservation or ideological commitment.
By grounding conservation in Natural Law, environmental ethics becomes intelligible, objective, and publicly defensible. It follows from a rational account of what human beings need in order to live well together over time. This prepares the way for deeper questions about sustainability, biodiversity, and humanity’s obligations to future generations, which will be addressed in the final lesson of this section.
Video explaining green initiatives in North Texas (auto-generated CC).
3.4 | Ethics of Sustainability & Biodiversity
Central Question: Do we have moral obligations to future generations?
Sustainability & Moral Continuity
Natural Law ethics evaluates actions according to whether they support the conditions required of human flourishing.
Because human life unfolds across generations, moral reasoning cannot be restricted to immediate outcomes alone. Rational agency includes the capacity to anticipate long-term consequences and to act in ways that preserve the goods upon which future lives will depend.
This temporal dimension of moral responsibility is captured by Sustainability, the use of resources in a manner that meets present needs without undermining the ability of future generations to meet their own. Sustainability is not a technological preference or a political trend. It follows directly from the recognition that future generations will possess the same basic goods as our own time and will depend on similar material conditions in order to flourish.
Natural Law teaches that human beings are not entitled to exhaust shared resources merely because they currently control them. Clean water, fertile soil, stable climates, and functioning ecosystems are not optional benefits. They are material preconditions for life, health, social cooperation, and education. Practices that knowingly compromise these conditions for short-term gain violate the Natural Law.
Sustainability, therefore, reflects moral continuity across time. Present communities inherit a world shaped by past decisions and, in turn, shape the conditions under which future communities will live. Ethical responsibility includes restraint, planning, and stewardship. Actions that irreversibly damage ecological systems represent failures of rational foresight rather than unavoidable necessities.
Natural Law does not require perfect prediction of future outcomes. It requires reasonable attention to foreseeable consequences. When evidence indicates that certain practices degrade soil, deplete water sources, or destabilize ecosystems, continuing those practices without modification becomes morally suspect. Sustainability expresses the obligation to align human activity with the long-term requirements of flourishing rather than immediate convenience.
Hunting, Farming, & Stewardship of the Land
The ethical implications of sustainability become clearer when applied to concrete human practices such as hunting and farming. These activities have sustained human societies for millennia and remain morally legitimate within a Natural Law framework. Their ethical status depends not on their existence, but on how they are carried out.
Natural Law distinguishes between moral agents and morally relevant entities. Non-human animals are not moral agents, as they do not deliberate about right and wrong. However, animals are morally relevant because their treatment affects human goods such as life, social stability, and ecological balance. Ethical obligations toward animals arise indirectly through the requirements of human flourishing.
Ethical hunting practices illustrate this reasoning. Managed hunting can contribute to population control, ecosystem stability, and food provision. Principles such as fair chase, selective harvesting, and avoiding waste reflect ethical restraint and proportionality. These practices align human use of wildlife with ecological limits, preserving conditions under which both our communities and ecosystems remain stable over time.
Farming presents parallel considerations. Agriculture is essential to sustaining human life, but its methods significantly shape environmental outcomes. Practices that preserve soil fertility, protect water quality, and minimize long-term ecological damage support the basic goods identified by Natural Law. Conversely, farming methods that exhaust land, pollute waterways, or rely on unsustainable inputs undermine the material foundations of Natural Law.
Ethical farming also reflects intergenerational responsibility. Soil depletion, aquifer exhaustion, and habitat destruction compromise the ability of future communities to feed themselves. Sustainable agricultural practices, such as crop rotation, rotational grazing, and humane livestock treatment, demonstrate rational stewardship rather than narrow economic calculation.
Video explaining the environmental objectives of Texas Parks & Wildlife (auto-generated CC).
Biodiversity & the Ethics of Ecological Stability
Beyond individual practices lies a broader ecological concern captured by Biodiversity, the variety of life within ecosystems, including diversity of species, habitats, and genetic traits. Biodiversity is not merely a scientific classification. It functions as an indicator of ecological resilience and stability.
From a Natural Law perspective, biodiversity matters because resilient ecosystems are necessary for sustaining human goods. Diverse ecosystems regulate climate, purify water, maintain soil fertility, and reduce vulnerability to disease and collapse. When biodiversity declines, ecosystems become fragile and less able to adapt to stress, threatening food systems, public health, and social order.
The moral relevance of biodiversity does not depend on emotional attachment to wildlife or aesthetic appreciation of nature. It arises from rational recognition of dependence. Human flourishing requires ecological systems capable of maintaining stability across time. Biodiversity provides that adaptive capacity and therefore supports the goods that Natural Law identifies as objective and universal.
This framework also clarifies the limits of environmental obligation. Natural Law does not require preserving every species at all costs, nor does it assign equal moral status to all forms of life. Instead, ecological decisions are evaluated according to proportionality, necessity, and long-term impact on human goods. Moral reasoning remains grounded in human flourishing while acknowledging ecological interdependence.
Loss of biodiversity typically results from cumulative human actions rather than isolated choices. Habitat destruction, pollution, and overexploitation erode ecological complexity gradually, often unnoticed until critical thresholds are crossed. Natural Law emphasizes responsibility precisely at this stage, where rational foresight can still prevent irreversible damage.
This Section: Applied Ethics I - The Environment
Next Section: Personal Character | Aristotle