Patrick Lee

Professor of Philosophy

Franciscan University of Steubenville


How is human nature related to moral goodness?  In what way is human nature normative?  These are the questions I shall address from the perspective of a natural law theorist, or to be more specific, from the perspective of what is often called the new natural law theory, in the line of Germain Grisez, John Finnis, Joseph Boyle, and others.  To approach the question, I shall first specify one way I think human nature is not morally normative.  I shall then explain what I mean by nature when speaking of human nature, how I think free choice is related to human nature, how we reach basic practical insights and basic moral principles based on our nature, and I shall conclude by considering some theological worries about our natural knowledge of basic moral principles. 


I.                   Human Nature is Not Itself the Moral Criterion


One idea of how human nature and morality are related is, in effect, that human nature just is the moral criterion.  This idea can be expressed quite simply, in the popular arena, or developed in a sophisticated way (in, for example, the thought of Francisco Suarez and scholastic followers of him, who, nevertheless often mistakenly claimed they derived their view from St. Thomas Aquinas).  In either case, the thought is that human nature as given, as a structure, and the biological and spiritual tendencies themselves which are parts of human nature, constitute the moral criterion in this sense:  when one asks whether an action is right or wrong one simply compares the direction of the action to human nature or some part of human nature; if the action conforms to human nature—if basically the pattern of the action is the same as the pattern found in human nature—then the action is morally permissible; if the action does not conform to human nature then it is morally wrong.[1]  This, I think, is an oversimplified view of how human nature is normative or grounds moral principles. 

Take the example of the kind of argument this view has presented against lying.  Proponents of this view might say that lying is wrong because it does not conform to the natural orientation or teleological direction in the faculty of speech—that the faculty of speech is naturally oriented to communicating what one thinks is true, but lying prevents that faculty or power from attaining its natural end and is therefore immoral.  The central problem with this type of argument is that, given this conception of nature, it is not clear that we are morally required to keep within the guidelines, or limitations set for us, by human nature.  If I use a basic power or faculty but direct it toward an end to which it is not naturally directed, why is that necessarily wrong?  May it not just be ingenuity on my part, an end-run around the basic equipment I have been born with?  Also, it is not clear that it is always wrong to act against every faculty or power natural to us—for example, it does not seem to be intrinsically wrong to induce vomiting, even, say, for experimental purposes, in order to discover the nature of digestion.  (Let me add parenthetically, that I agree with many of the conclusions these arguments were supposed to support—I hold, for example, that lying, contraception, and extramarital sex are morally wrong—but I do not think this approach shows why these acts are wrong.) 

Nor do I think that human nature is a norm the way in which some Aristotelians have argued (whether Aristotle himself held this position in every part of his ethics is a vexed question I will simply set aside here).  Some Aristotelians have argued that human nature grounds morals by indicating to us the capacity that is distinctive of human beings, and, because distinctive, most excellent.  And so, on this view, the morally ideal life is to develop to its utmost that part of us that is distinctive of us.  I see several problems with this approach—though, I must apologize, that, for lack of time, I have stated it rather boldly and without, as they say, “nuances.”  In any case, the central problem with this approach is that it ignores the fact that it is only in the abstract that we share various capacities with other animals.  True, both we and other animals are biologically alive and reproduce.  But the biological life of a human being is fundamentally different in kind from the life of a dog or a cat.  That is, in human beings there is not one half that is animal and the other half personal; rather, the life of a human being is through and through both a biological and personal life.  This also is clear with reproduction:  humans reproduce, but they reproduce in their own distinctive manner, and what is generated is not just a biological entity, but a whole human, personal being with both body and rational soul.



II.               Human Nature

So much for how human nature is not the criterion.  Now let us examine how human nature is a ground of practical and moral norms. 

The nature of a being is its internal structure or set of tendencies that distinguishes it from other types of beings, coming from within, rather than imposed from outside.  Some thinkers, notably existentialists, deconstructionists, or anti-realists, have denied that humans have a nature in the proper sense of the term.  According to these thinkers, by our free choice or preferences, we construct what we most fundamentally are.  Indeed, anti-realists of various types deny that there are real natures outside the human realm as well, holding that we construct or impose all meaning rather than discover any objective structures, or at least any important objective structures.  It is clear, however, that when we begin to make something or to interact in any way with the external world, we must take account of pre-existing differences in those things we interact with.  Prior to our projects and plans, different things have within them inherent tendencies to act and react in certain definite ways.  Thus, we treat a tree differently than we treat a Rottweiler dog—we might kick a tree to vent our anger but will not likely kick a Rottweiler to vent our anger.  The reason is obvious:  within the Rottweiler dog there is an inherent tendency to act and react in a way fundamentally different than a tree.  In other words, the dog has a different nature than the tree.  Things in the world differ in that they are different types of agents—within each thing is a tendency, or an ordered set of tendencies, to act and react in certain ways.  This inherent tendency or set of tendencies is the thing’s nature.  Aristotle spoke of nature as the intrinsic principle of motion and rest in a being, that is, the internal source of its tendencies to act and react in certain ways, or (put still another way) the internal source of the entity’s basic potentialities. 

Understood in this fashion it is clear that human beings do have a nature.  Human beings have basic potentialities that are not acquired, not constructed, not imposed, but are inherent within them, basic potentialities that they have just by coming to be, that is, potentialities they have in virtue of what they are.  And so human beings do have a nature.  Human beings have the inherent potentialities to maintain their organic states, to grow, to reproduce, to perceive, to remember, to imagine, to have emotions, to understand, and to will.  Not every human being can immediately exercise all of these potentialities, but every human being is oriented to actively developing himself or herself to the stage at which he or she will perform such actions.   


III.           Human Nature and Free Choice

Now to how human nature is related to free choice.  I will bypass here most of the complicated disputes about responsibility and free choice, and presuppose that we do sometimes make free choices.  Here I want to ask how our free choices are related to our nature.  Both those who deny that we have a human nature, or that it has any role to play in morality, and those who just make human nature itself the moral norm, both view free choice and human nature as in tension or as opposed. Both groups view human nature as a limitation or restriction placed from the outside on our freedom or our choices.  This is obvious for those who deny human nature or its significance, for they deny it in order to make room for freedom or choice.  It also is true of those who view human nature as a pattern simply to be conformed with, for according to them it turns out that a morally good act is one that is within the limits of human nature and a morally bad act is one that strays outside those restrictions.

But this is a profoundly mistaken view of how free choice and nature are related.  Free choice is not something that occurs as opposed to or as outside the framework set by one’s nature.  To put the point briefly, we choose among possibilities that are open to us, but what possibilities are open to us is set by our human nature.  To express the point slightly differently:  we choose actions, but actions are, in one way or another, actualizations of one or more of our basic potentialities.  So, free choice occurs within the context of human nature—we do not choose to keep within human nature or to go outside it.

When I choose I choose among possible courses of action.  For example, I may choose to eat breakfast or to skip breakfast, I may choose to go to the gym to work out or to go home and study.  Each of these possible courses of action is attractive, is of interest to me, because each, in one way or another, actualizes some basic potentiality in me.  What makes a course of action attractive, what makes it desirable, and so in some basic sense, good, is that it is some way fulfilling for me or those that I care about.  A possible action is desirable or good (not yet morally good, but practically good) to the extent that it is, or at least seems to be, fulfilling (or is a means to an activity or condition that is, or seems to be, fulfilling). 

So each choice is a choice to realize or actualize one’s potentialities in some way or other.  Since we are complex beings we have various basic potentialities.   The actualizations of our basic potentialities are what natural-law theorists generally call basic human goods, or fundamental human goods.  Such basic goods are the actualizations of the kind of being we are.  So, freedom is not anti-thetical to nature; rather, our nature sets the possibilities within which we act.  But our nature is not a limitation set upon our freedom or our desires either.  Rather, the orientation to various types of fulfillment makes possible our choices and our active, free self-constitution in our choices. 

I will return more fully to the issue of moral goodness shortly, but it is worth making a brief remark about it here at this abstract level.  What could be the difference between morally good choices and morally bad choices, if whenever we choose we are choosing to pursue some basic good or other (or at least some fragment of a basic good)?  Whenever we choose we are seeking to actualize one or more of our basic potentialities.  Since, according to the natural law tradition goodness is the fullness of being possible for an entity, or the actualization of its potentialities, the point I just made can be re-phrased as follows:  whenever we choose we are seeking to realize some good or other.  But if that is so, then how can we ever do what is morally wrong? 

The answer is that there are two ways of seeking to realize one’s potentialities, that is, two ways, of seeking fulfillment or the good.  One can seek a good in such a way as to remain open to and respectful of all the goods not sought in this choice—and that is a morally good choice, or one can seek a good in such a way as to turn away from, or diminish in oneself a respect for, some other good (either in oneself or in another). 

Thus, human nature is the ground or criterion for what is morally good without being a limitation on free choice.  It is not as if morally good choices are those in line with nature and morally bad ones follow our desires and lead us outside the limits set by nature.  Rather, all choices realize our potentialities (or develop our nature) in some way or other, but morally bad ones realize our potentialities in a way that diminishes or mutilates in some way our further openness to other basic goods.  Nor is it that morally good choices are for the sake of good objects and morally bad ones are aimed at bad objects. Rather, all choices are for the sake of something to which we have some natural orientation, toward something good (or at least apparently good) but bad choices pursue a good in such a way as to suppress our appreciation of some other good (either in ourselves or in others).   


IV.            Basic Practical Principles


The third point in our examination of how nature is related to morality is how we arrive at first practical principles—practical principles which are not yet, as I shall explain in a moment, fully moral principles.  How, from these practical principles, we reach specifically moral principles, I shall examine in the next section. 

Famously, David Hume held that any argument in which all of the premises are is-propositions, or descriptive propositions, and yet the conclusion is a moral ought proposition, commits a fallacy.  Some natural law theorists have protested that this is not a fallacy, that propositions describing human nature together do imply moral propositions, and have held that the basic moral principles are deduced from propositions describing human nature.  However, on this one point I agree with Hume (of course that is what, in part, puts me in the camp of the “new natural lawyers”).  What Hume called a fallacy is a fallacy.  For a practical proposition is a fundamentally different sort of proposition than a theoretical or speculative proposition—that is, an is-proposition.  A theoretical proposition attempts to describe what is the case.  In a theoretical proposition one is attempting to conform one’s mind to what is (I am presupposing here a realist position on theoretical propositions).  In a practical proposition, however, one is attempting to order acts of will, to put order in an act that has not yet come to be.  A practical proposition is not a description but a directive or a prescription.  Now, in an argument the knowledge of the premises is the cause of the knowledge of the conclusion.  And the effect cannot be greater than the cause.  And so if all of the premises are telling us about what is the case, then, absent some implicit presupposition about what ought to be done, then those premises cannot by themselves generate knowledge about what ought to be done.  (I do not say that some theoretical knowledge is not presupposed for practical and moral knowledge and arguments—to have ethical knowledge about killing and letting die, for example, one must know, at least in a general way, what life is, that we can do things to endanger or end life, and so on.  But my contention is that the first principles of practical reason, and the first moral principles, are not established by arguments all of whose premises are theoretical, for example, theoretical propositions about human nature.)  So, while moral norms are grounded in human nature, they are not deduced from propositions describing human nature. One need not first do philosophy of human nature before doing ethics.  The first practical principles and the first moral principle are, in my view, self-evident and underived from any other propositions, even though they arise out of insight into the possibilities toward which we are oriented by our human nature.  One could put it this way:  they are ontologically grounded in human nature even though they are not logically derived from propositions about human nature.   How, then, are they known, and how do they generate specifically moral propositions? 

The key texts in the history of the natural law theory are, of course, found in St. Thomas Aquinas.  According to Aquinas the first principles of practical reason are per se nota, that is, known through themselves, not deduced from any other propositions.  And they are per se nota, or self-evident, because in each of them the predicate is contained within the intelligibility of the subject—so once one understands the subject one thereby grasps that the predicate belongs to it.  An example in the theoretical order would be:  if one knows what grass is, then one knows the truth of the proposition that grass is a plant:  knowledge of the nature of the subject tells one that the predicate belongs to it.  Something similar, but in a practical directive, occurs in the knowledge of the first practical principles.  Aquinas has this to say about how these first practical principles are known: 

Since indeed good has the intelligibility (ratio) of end, and evil the intelligibility of its contrary, hence it is that all those things to which the human being has a natural inclination, reason naturally apprehends as good, and consequently, as to be pursued by action, and their contraries as evils and to be avoided. (Summa Theologiae, I-II, q. 94, a.2) 

In other words, by a practical insight one directly apprehends in the object of a natural inclination that this object is perfective or fulfilling and thus is good and to be pursued.  This language of “to-be-pursued” (Aquinas uses the gerundive to express the prescriptive mode, as opposed to the indicative) indicates that the proposition is a directive, a prescriptive proposition, not a descriptive or theoretical proposition.  I believe Aquinas’s point here is correct.  The basic practical propositions he is describing here are propositions or directives toward the objects of our natural inclinations or our basic potentialities.  Thus, we arrive at such propositions as:  Life is good and to be pursued, marriage is good and to be pursued, knowledge is good and to be pursued, friendship and society is a basic good and to be pursued, religion is good and to be pursued—these are the basic goods Aquinas lists (without claiming to provide a complete list.  Following Grisez, Boyle and Finnis, I would add some others, such as play or skillful performance, aesthetic experience, and self-integration.[2]  In any case, how do these insights with respect to the objects of our natural inclinations occur? 

I think they occur as insights into experience of conditions or activities that are genuinely fulfilling.  For, from the experience of these conditions or activities one comes to understand that, for example, health, knowledge, or harmonious relationships with other people, are of themselves fulfilling and thus worthy of being pursued.  This insight is not an inference.  Rather, if one grasps health, for example, as genuinely fulfilling, that is at the same to grasp it as to-be-pursued.  An object’s being genuinely fulfilling is the intelligibility under which one sees it as worthy of pursuit.  The natural inclinations are, in a way, data for the practical insight.  How this occurs may be illustrated, I think, in the following way.  As a young child I experience being healthy as opposed to being sick or having my knees scraped up or having burnt fingers.  I enjoy, or take delight in, being healthy, and I dislike, or have an aversion to being sick or wounded.  That of course is not yet a practical insight; the enjoyment or aversion so far mentioned is on the level of emotion, or what Aquinas called sense appetite.  But at some point as a child I go further and I come to understand that being healthy is a condition worth pursuing, and being sick or wounded is a condition I should take steps to avoid.  What has occurred here is a practical insight, an act of intellect, an insight that being healthy is fulfilling and thus worthy of pursuit, protection, deliberation about, and so forth.[3]  These first practical principles, it should be noted, are at the basis of anyone’s practical deliberations.  They are at the basis of the practical deliberations when we decide to do something morally good, but also at the basis of practical deliberations when we decide to do something morally bad.  We cannot begin to think about what to do unless we understand some point, or some points, to acting.  Just as one will not begin to think about what road to take unless one sees some point in going somewhere, so one cannot begin to deliberate about what action to choose unless one first apprehends some goods worth pursuing.  These first practical principles are just the knowledge that some activities or conditions are worth pursuing, promoting, or preserving.  .  


V. From Practical Principles to the Basic Moral Principle


So, given the first practical principles, where does morality come in?  The practical proposition that health is a good worthy of pursuit is not yet, or not yet formally, a moral proposition.  The moral issue arises when, having seen and appreciated various basic human goods, such as health, friendship in a broad sense, understanding, and so on, one finds oneself in a situation where one could choose in two distinct manners.  One could choose in a way that is fully in accord with all of these practical principles, or one could choose in a way that is in accord with at least one of them to a certain extent (else the option would not be attractive), but that is not fully in accord with all of them.  And one’s emotions have a role in making the unreasonable option attractive.  Thus, moral normativity does not arise from an entirely new proposition or new contrast.  The difference between morally good choices and morally bad choices is not that morally bad choices aim at something bad—badness is not a nature possessed by any thing but is a privation.  Nor is the difference between the morally good and morally bad choices that morally bad ones are only in one’s self interest and morally good ones are subjected to an implicit contract—though there are some morally bad choices which fit that description.  Rather, because, as Augustine, Aquinas and many others pointed out, goodness is the fullness of being due a thing, the difference between morally good choices and morally bad ones is just that the good choices are fully rational, they have the fullness of being possible for a human choice, while the bad ones in one respect or another, are lacking in regard to the integral directiveness toward every aspect of human good that comes from the first practical principles in their totality and fullness. 

So, morality and nature are closely interrelated, indeed, one can say that moral norms are grounded in human nature, even though they are not deduced from propositions describing human nature.  However, to be clearer about the relationship, one perhaps should say that morality directs us to real human fulfillment (and I should add, not just individual fulfillment, but fulfillment in communion with other persons).  Morality is based, not on human nature viewed as a static pattern or structure, but rather on genuine goods, the basic goods, to which we are directed by our nature.  This clarification or qualification is important for at least three reasons. First, it makes it clear that natural law need not be conceived as a set of limitations or as primarily negative.  On the contrary, when the emphasis is on the goods to which we are oriented by our nature, then the positive comes first:  the basic moral norm is:  energetically pursue and promote the basic human goods both in oneself and in others.  The prohibitions, such as do not intentionally kill innocent persons, do commit adultery, and so on, excludes choices and actions which are themselves negative.  The second reason for the importance of this clarification (namely morality is based on the goods we are naturally inclined to, not immediately on a nature conceived statically)—is that it makes clear that we are not all called to have the exact same type of life; there is room for a great deal of diversity and ingenuity in living out the moral life.  There are many basic goods, not just one, and there are perhaps an infinite number of ways of realizing these various basic goods.  We are not all called to realize all the basic goods equally, or in the same order—we are called to fashion a life in which we energetically pursue some, and at all times to respect all of them, both in ourselves and in others.  But natural law theory, correctly developed, does not prescribe that human beings attempt to be carbon copies of one another.  And the third reason why this clarification is important is that it leaves room for supplement by faith and grace.  The natural basic human good of religion invites us to inquire whether perhaps God might approach us to establish more than a natural harmony with him.  The natural law directs us to human fulfillment, but it is, correctly understood, open to God’s invitation to the supernatural, that is, something more than human fulfillment. 


V.               Human Nature and Divine Grace

So far I have not appealed to special revelation or religious faith.  However, my claim that there are basic moral truths in principle knowable without appeal to special revelation, may cause worry, even consternation, among some Christians.  Thus, H. Tristram Engelhardt, commenting on an article I wrote on abortion in the journal Christian Bioethics, complains about my “commitment to natural reason.”  He then says that, “This commitment to natural reason, characteristic of much of Roman Catholic bioethical analysis, tends to reduce moral theology and Christian philosophy to secular philosophy and to be distinguished by an accidental connection to the particularities of Christian commitments.”[4]  Thus, I would like to say something brief here, from a theological standpoint, in reply to the concern Engelhardt enunciates.

The goal of the Christian life is the completion of the Kingdom of God.  As Our Lord says, “Seek first the kingdom of God and his righteousness.” (Matt., 33; cf. Lk., 12:31).  The Kingdom of God centrally involves a mysterious sharing in divine life.  At Baptism we are made children of God, no longer just children of men.  We have a “share of the divine nature”, says St. Peter, and St Paul speaks of “the Holy Spirit poured forth in our hearts.”  So, as Christians faithful to His invitation, we have in us, mysteriously, the divine life itself.  This sharing in divine life can become more intimate and will become matured, or brought to fruition, in heaven, in the completed Kingdom of God (I believe Jesus was referring to this sharing in divine life, or grace, when to the Samaritan woman at the well He said, “And whoever drinks of the water I shall give him will never thirst; the water that I shall give him will become in him a spring of water welling up to eternal life.” (Jn., 4:14). 

But I believe also, first, that the eternal Kingdom begins now in mystery, that it is not just in the future, though it is completed only in the next world.  For, Our Lord says that the Kingdom of heaven, or the Kingdom of God, is at hand, though it is like a mustard seed, and must grow.  So we begin even now to share in, and with God’s grace, to help build up, God’s kingdom, or, with God’s grace, prepare the materials for the eternal banquet.

Second, the Kingdom of God includes not only a personal communion with God, which is supernatural (the divine nature in us), it also includes, as an essential component, human fulfillment.  In the completed Kingdom there will be the mysterious, intimate personal communion with God, the seeing of God face to face, the beatific vision, but also complete human fulfillment.  As a Catholic I heed the words of the Second Vatican Council, which said: 

For after we have obeyed the Lord, and in His Spirit nurtured on earth the values of human dignity, brotherhood and freedom, and indeed all the good fruits of our nature and enterprise, we will find them again, but freed of stain, burnished and transfigured, when Christ hands over to the Father: "a kingdom eternal and universal, a kingdom of truth and life, of holiness and grace, of justice, love and peace." (reference to the Liturgy of the Feast of Christ the King)   On this earth that Kingdom is already present in mystery. When the Lord returns it will be brought into full flower.

Thus, the Christian life does include duties that transcend the fulfillment of human nature and cannot be known, even in principle, by natural reason unaided by the gift of faith.  For example, we have a duty to accept God’s Revelation handed on to us by Scripture and Church teaching, and this Revelation contains a proposal from God to enter into a personal communion with him, and to imitate Christ’s life, and, with God’s grace, to join ourselves to Christ’s offering of himself on the cross for our sins, for it is by our being joined to that offering, that obedience unto death, that Sacrifice, that we are brought into that intimate personal communion with God, called grace or sharing in the divine nature.  We are thus called to do pray, to do penance for our sins, to participate in the Sacraments in which (according to Catholic belief) Christ’s sacrificial offering on the cross is made present to us.  Hence Catholic Christians believe that Christians have specific duties not discoverable by the natural light of reason.

At the same time, if the Kingdom of God does include both human fulfillment as well as supernatural communion in divine life, it does not seem possible that the human part of what we are to work for as part of God’s kingdom would not be at least in principle discoverable by the natural light of reason.  If it is part of human fulfillment, then it is proportionate to human nature, and thus it is hard to see why it could not be discovered, examined, reflected upon, and so forth, by the human intellect, even a human intellect that is darkened by sin and possibly in a human being who has not accepted, or has rejected, God’s invitation to enter with him a personal communion.  It might be very difficult for such a person to see some moral truths that are very difficult to follow, but I do not see how we could rule out in advance that possibility.  

Still, we should add that the human intellect will certainly operate much more reliably, even as a human intellect, if it operates within the context or horizon of faith.  There is no doubt that selfishness, pride, envy, lust and so on often bias the operations of the intellect.  So, charity, humility, chastity, and, above all, faith, can help to heal that bias. 


[1] Cf.: Germain Grisez, Joseph Boyle, and John Finnis, “Practical Principles, Moral Truth and Ultimate Ends,” American Journal of Jurisprudence 33 (1988) 99-151; John Finnis, Joseph M. Boyle, Jr., Germain Grisez, Nuclear Deterrence, Morality and Realism (Oxford: Oxford Univer­sity Press, 1987), chaps. 9-11. John Finnis, Fundamentals of Ethics (Washington, D.C.: George­town University Press, 1983); John Finnis, Aquinas, Moral, Political, and Legal Theory (Oxford: Oxford University Press, 1998); T. D. J. Chappell, Understanding Human Goods:  A Theory of Ethics (Edinburgh: Edinburgh University Press, 1998)

[2] Cf. Germain Grisez

[3] Following this practical intellectual insight, there occurs Aquinas refers to as simplex voluntas, that is a simple act of will, that is, a simple act of will in regard to an understood good—not a choice, which involves a willing to do something to bring about an instance of this good, but rather, simply a favorable inclination in the will toward the specific understood good.  It seems to me that this simplex voluntas is part of the answer to the neo-Humeian argument that a reason for action must be motivational but that an understanding without an act of will is not motivational:  the answer is to distinguish volitional acts—the practical principle is necessarily motivational with respect to a simplex vountas, but not necessarily motivational with respect to a choice.


[4] H. Tristram Engelhardt, Jr., “Moral Knowledge:  Some Reflections on Moral Controversies, Incompatible Moral Epistemologies, and the Culture Wars,” Christian Bioethics 10 (2004), 79-103, at 81.