Forbidden Fruit: The Ethics of Humanism


Norman L. Geisler

Article ID:



Jul 7, 2023


Apr 22, 2009

This review first appeared in Christian Research Journal Fall (1988). The full text of the article can be obtained by clicking here. For further information or to subscribe to the Christian Research Journal go to:


A Summary Critique: 
Forbidden Fruit: The Ethics of Humanism
Paul Kurtz

(Prometheus Books, 1988)

In this major work defending the ethics of secular humanism, Dr. Paul Kurtz, author of Humanist Manifesto II (1973), sets forth his goal “to show that there can be an objective and positive humanist basis for ethical conduct” (p. 17). He believes that a positive, objective ethic is possible without God, for “we, not God, are responsible for our destiny” (18).


In the Manifesto Kurt had written: “No deity will save us; we must save ourselves” (16). Forbidden Fruit is Kurtz’s attempt to show how this is possible. Taking his title consciously from Genesis 3, he affirms an ethic which is “based on a scientific and naturalistic theory of nature and human nature and is grounded in the rational knowledge of good and evil” (16). He says boldly, “Eating of the fruit of the tree of life gives us the bountiful enthusiasm for living. The “ultimate” value for the humanist is the conviction that life can be found good in and of itself,” that is, apart from God (240).

No Need for God

According to Kurtz, “To ground ethics in God only pushes skepticism one step backward and does not advance the argument” (149). Furthermore, “many people who profess belief in God neglect their moral duties and actually break moral principles. Thus belief in God has proved time and again to be an insufficient ground for guaranteeing moral behavior” (149). (Kurtz fails to note that humanistic ethics is notoriously ineffective in ensuring moral behavior.) He adds that it is futile to base ethics in God, “for the God of orthodox theism is no longer believable to the scientific humanist” (238). For Kurtz, “it is an anthropomorphic expression of conceit to believe that God created man in His own image.” On the contrary, “we created God in our image to fulfill our dreams and hopes of eternity” (238). So “the theist’s world is only a dream world; it is a feeble escape into a future that will never come” (243).

No Need for God’s Commands

Of course, if God does not exist, then it follows that His command is not the basis for moral duty. According to Kurtz, “to passively obey the Ten Commandments or the injunctions of Jesus without being able to define or evaluate such prescriptions is hardly to have attained ethical awareness” (43). Furthermore, “fear of punishment or hope of reward is hardly an ethical reason to follow God’s commandments” (149). Indeed, Kurtz believes that “the theist’s argument is immoral, for it abandons the moral conscience for an authoritarian ground, and thus sidesteps the content of the moral imperative itself” (150). “Ethical principles cannot be deduced from the concept of God,” for “theists have ‘deduced’ any number of moral codes at variance with those held by other believers” (72). (He does not mention, of course, that humanists have the same problem.)

Morality is Prescriptive and Objective

A Moral lawgiver is not the source of moral law. Rather, says Kurtz, “we must create our own ethical universes” (18). Ethics is, nonetheless, “normative” and “prescriptive” (55), and “imperative” (150).* Kurtz rejects a purely subjective approach to ethics and argues instead for an “objective” ethic (65), which he calls “objective relativism.” Some moral principles are objective in that they are “expressions of the collective ethical wisdom of the race” (73). Thus there “are objective standards for judging the ethical principles that govern our lives.” He calls them “objectively true” with “cross cultural dimensions.” They comprise “common moral decencies” and express “the deepest wisdom of the human race” (80-81).

Kuntz’s catalogue of these objective moral principles includes integrity, truthfulness, promise-keeping, sincerity, honesty, trustworthiness, fidelity, dependability, benevolence, good-will, nonmalfeasance, beneficence, fairness, gratitude, accountability, justice, tolerance, and cooperation (80-96). Where did all these moral principles come from? Kurtz speculates that:

. . . one can imagine a possible scenario in the dim past of our forbearers, when the glimmering of what I shall call the common moral decencies emerged: be kind and considerate to the members of your tribe; be honest and truthful; do not maim, injure, or harm them needlessly; be sincere and keep your promises, etc. (67-68)

How Moral Principles Are Justified

Just how were all these moral principles derived and how are they justified? They arose by trial and error over long periods of time. They were justified by their results. “The test of truth of these principles was their consequences,” for “the tribes that developed such rules had less discord and could better survive than those that did not.” As anyone can see, “it is far more beneficial for everyone to cooperate; it works pragmatically in the long run” (68).

In spite of the fact that Kurtz believes that results determine rules, he does not wish to be called a utilitarian (64). He says, “by referring to the test of consequences, I do not mean simply the utilitarian greatest-happiness principle.” This is because, “if taken literally, this can lead to unfortunate results. Can a majority, for example, deny the rights to recalcitrant minorities, if this would lead to the greatest good for the greatest number?” Kurtz answers abruptly, “Surely not, for there are certain principles and rights that should not be eliminated, no matter how beneficial the results would be to the majority” (77).

Rather than one single utilitarian principle, Kurtz argues that “the test or consequences is plural and not singular, for we cherish many values and principles that we wish to preserve….To seek to derive a single principle may endanger the entire body of our value principles” (77). Hence, he does not want individual rights to be swallowed up in utilitarian ends. He would seem to be arguing more for the greatest good for everyone than just the greatest good for the majority.

Moral Principles are General, not Universal

In spite of his belief in objective moral standards and a desire to apply them transculturally, Kurtz emphatically rejects any absolute or universal moral laws. “I am unwilling to say that it is absolute or universal, for any one principle may clash with others, and there may sometimes be exceptions” (58). Thus moral duties are “prima facie general principles to which we are obligated in the sense that we ought to follow them” (58).

For Kurtz, however, there are no unconditional duties. “One has a conditional, rather than a categorical duty; it is more like a hypothesis than a dictate, amenable to critical interpretation and appraisal before it is applied in a concrete situation” (64). In this sense Kurtz’s view is not unlike another signatory of Humanist Manifesto II, Joseph Fletcher, who contended that general moral principles were only formal and contentless until they were filled in with the “existential particularity of the situation.” Kurtz, however, stresses that “a general principle ought to be followed unless good reasons are given to demonstrate why it need not be” (64).


Needless to say, there are many positive features to this humanistic ethic. Let us consider a few of the most obvious ones.

Ethics Is Objective

Confessionally, and to a large degree practically, Professor Kurtz avoids the radical subjectivism of an A. J. Ayer or a Jean Paul Sartre. Contrary to both emotivism and existentialism, Kurtz does believe in objective, knowable, and stateable moral principles. Indeed, many of these moral principles are commendable. In fact, while pondering his stated list of virtues, I could not help but note the similarity with those common to great cultures that were collated by C. S. Lewis in his famous appendix to The Abolition of Man. It should not be surprising that an avowed unbeliever can come up with such a noble list of virtues. After all, God’s moral law is “written on their hearts” (Rom. 2:15).

Ethics Is Prescriptive

Also commendable is the confession that ethics is not descriptive but prescriptive He rightly rejects the “is-ought fallacy” (74). Moral duty comes from an ought, not an is. In other words, one cannot argue that what people are doing is what they shou1d be doing. Morality is imperative, not just declarative; ought transcends is. In this Kurtz is to be commended.

Ethics Is Realistic

Kurtz does not have his head in the sand. He realizes that there are real moral conflicts. Even the best moral principles sometimes clash with one another (58). Since he does not accept the biblical doctrine of the depravity of man (248), Professor Kurtz is overly optimistic about human goodness. Yet in view of his tour of duty in World War II he confesses: “My own personal experience of the crimes of Hitler and his followers sears my memory.” Admittedly, “the most profound depths of human depravity have been revealed in modern times: The Nazi era is one such testimony to human evil” (249).

Ethics Is Pro Human

One unmistakable virtue of a humanistic ethic is its stress on the dignity and value of human beings, and in Kurtz’s case individual human beings. He is not defending a radical socialism that swallows up individual rights. In fact, he speaks loudly for “the right to life” (185), “the right to learn” (190, 203), the right to freedom from slavery (32, 69), women’s rights (33), the right to humane treatment for criminals (192), and the right to “informed consent” in medical matters (217). Although he avoids the unqualified use of “unalienable rights,” he stresses that “all human beings are equal in dignity and rights” (191). Kurtz even goes so far as to say, “I must confess that I would prefer to call them, universal…” (185), but he resists the temptation, at least in principle.


In spite of the many fine features of this attempt by a noted humanist to have a consistent humanistic ethic apart from God, there are some serious, even fatal, problems with Kurtz’s approach.

The Unavoidability of Moral Absolutes

Kurtz’s careful language and many protests notwithstanding, he never does quite succeed at avoiding the universality and absoluteness of basic moral duties. The following examples will suffice to show this.

1) A Moral Imperative. Although Kurtz denies any “categorical duty” (64) his irresistible inclination to affirm the value of “critical intelligence” leads him to call it “the single most important ethical imperative” in his ethics (173, emphasis added). In point of fact, as the following quotations reveal, his language is often categorical, not hypothetical.

2) Principles that Apply to All Humans. In one case the inconsistency between confessing all duties are only general and the unavoidability of universal moral imperatives comes out in one sentence: he gives a positive answer to the question: “Are there any general ethical principles that apply to human beings, no matter what the society?” (63, emphasis added). But how can they be merely general if their application is universal?

3) Morality Rooted in Human Nature. On another occasion Kurtz admits that “moral imperatives” are “rooted in the nature of the human animal….” He even calls them “instinctive tendencies” (66, 67). This is strong language for someone who repeatedly denies the universal nature of moral duties.

4) Need for Universality. Not only does Professor Kurtz express a wish that some moral duties could be called universal (185), he even admits that “ethical cognition (i.e., the problem of how we know what is ethically right and wrong] points to the need for a universality in conduct, and it speaks to all men and women no matter what their social or cultural background” (69). But if there is a real need for universal moral duties, then why the real denial of their universality?

5) Moral Duties Extend to All Humans. In one place Paul Kurtz acknowledges that the “moral decencies” he enumerated “extend to all humans, and that a doctrine of human rights is developed for humankind in general” (70). Here again, if some moral duties extend to “all” of “humankind” and not just some, then why deny they are universal in their application?

6) Every Person is Entitled to Equality. While stressing a favorite humanistic doctrine of equality, Kurtz again yields to the irresistible temptation to universals. He declares that “each person is entitled to equality of consideration as a person, and as such has equal dignity and value” (71, emphasis changed). But if each and every individual has this right, then the right is universal. At other times he speaks of “humanity at large” (179) or an “ethical commitment to the world community” (198). But these are scarcely veiled euphemisms for his deep-seated, though unconfessed, belief in their universality.

Realizing this unavoidable urge to posit unconditional moral duties, Kurtz frankly confesses the “tendency to call these rights ‘universal’ or even ‘absolute’ — because they are so fundamental . . .” (184). Yet in spite of this he goes on to affirm that they “are no more than general . . .” (184), a not-so-carefully-concealed inconsistency.

A Lack of Proper Justification

Kurtz confesses to a pragmatic justification for moral principles, that is, they are judged by their results in the long run. But this has serious problems. First, no human being can know “the long run.” Hence, only God has the knowledge needed to be a pragmatist, and He is not! Second, something is not good simply because it brings the desired results. All that is proved by accomplishing the desired results is that the means chosen to get those results worked. It does not prove that the means or the desired results were good. Even when the desired results occur, we can still ask whether they were good or evil.

An Insufficient Source of Morality

Throughout his book Kurtz fails to provide an explanation for the source of his many culturally transcended and highly commendable moral prescriptions. Indeed, given his assumption of atheism such a task seems to be a logical impossibility, since there can be no moral prescriptions without a Moral Prescriber. As C. S. Lewis so forcefully reasoned in Mere Christianity, there cannot be moral legislation without a Moral Legislator. So the central problem with the humanistic ethic is that while the humanist can believe in many good moral principles, he has no real justification for these beliefs. It is logically impossible to have absolute moral laws but no absolute Moral Lawgiver. And, despite his protests to the contrary, we have already seen that Kurtz too has universal, unconditional moral prescriptions.

Unfounded Optimism

Kurtz’s own brand of optimistic humanism makes it difficult for him to accept that evil is endemic to the nature of man. Rather, he says: “I do not hold the doctrine of original sin. I do not believe that human beings are born depraved” (248). Thus he ignores the evils of man in general and even sweeps away the sins of tyrants in particular. Realizing he will be criticized for what he calls “excessive humanistic idealism,” Kurtz says: “I prefer to believe that such horrors [as Hitler’s] are aberrant and contrary to our deeper moral sensibilities” (251). So, in spite of his occasional flashes of realism, Kurtz is an incurable optimist. One cannot help but admire his unfounded optimism, when we remember that he neither believes in God nor an afterlife (235). Such faith is somehow admirable, even though it is groundless.

Biblical Illiteracy

Not atypical of humanists, Kurtz’s knowledge of the Bible leaves something to be desired. He wrongly believes that the Bible teaches slavery (32, 69), demeans women (33), approves of child sacrifice (41-42), offers a different morality in the New Testament than in the Old Testament (31-32), and encourages the exploitation of the environment (195). One is inclined to say that it would take volumes to respond to these false accusations. But on second thought, a little time with one volume will do it — the Bible.

Moral Inadequacies

Space permits only mentioning, not critiquing, a whole host of morally unacceptable activities upon which Kurtz places his humanistic blessing, including abortion (79, 215), euthanasia (37, 180, 221), sui­cide (79, 215), pornography (21,214), prostitution (211), adultery (207), and homosexuality (188, 208). Scanning this list of sins leaves no doubt in a Christian’s mind that, in accord with the title of his book, Kurtz has indeed eaten the “forbidden fruit”!

Norman L. Geisler

Dr. Geisler is professor of systematic theology at Dallas Theological Seminary and the author of numerous theological and philosophic works, including Options in Contemporary Christian Ethics (Baker, 1981).

* Normative means that the system of ethics includes “norms,” that is, standards of right and wrong. Prescriptive indicates that the ethical system makes statements about what ought to be done, as opposed to a purely “descriptive” approach which mere1y observes what people do. An imperative ethic is one in which people are told what they must do. — The Editor

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