“Each nation that has ‘liberal’ abortion laws has rapidly become, if it was not already, a nation of murderers.” The person who spoke those words was not Operation Rescue’s Randall Terry, or the Reverend Jerry Falwell, or some fundamentalist preacher from the Ozarks. She was one of the twentieth century’s most eminent academic philosophers”indeed, a woman who might fairly have claimed (though it would never have occurred to her to make such a boast) to be the greatest woman philosopher in modern history: G.E.M. Anscombe.

Anscombe, a Fellow of Somerville College, Oxford, who later succeeded her mentor Ludwig Wittgenstein in the chair in philosophy at Cambridge, spoke those words in a lecture delivered in German and published for the first time in English in Human Life, Action, and Ethics , a superb collection of Anscombe’s essays, edited by her daughter Mary Geach”a fine philosopher in her own right”and Geach’s husband Luke Gormally.

The volume brings together essays ranging from her profoundly influential article “Modern Moral Philosophy” on. All of the essays pertain to what philosophers, following Aristotle, call “practical reasoning.” Most are about what people have reason to do and not do, and what they ought to do and ought not to do. Not every essay is concerned with ethics, strictly speaking. Several, especially those in Part Two, focus on philosophical psychology and related subjects, elaborating and developing key ideas about how human acts are to be understood. (Of course, properly understanding human action is critical if we are to evaluate it intelligently from the ethical point of view.) It was work in this area”above all her 1957 book Intention ”that established Anscombe as an intellectual giant. As Mary Geach observes in the book’s introduction, “ Intention changed the consciousness of Anglo-Saxon philosophy, making everyone aware that actions are intended under descriptions, and that they are at least to be judged under those.”

Most of what is set forth in the essays in the final part of Human Life, Action, and Ethics will be of interest principally to professional philosophers. But the earlier essays are accessible to general readers and will be interesting to anyone who aspires to think rigorously about moral theory and normative ethics. Of course, as anyone familiar with Anscombe’s writings knows, reading her work is never an effortless task. As Mary Geach says, “She does not carry the reader along, as some authors do (Newman is an example). Yet some people prefer her sort of writing, like the confection panforte , all fruit and nuts and no dough, very chewy and tough.”

Anscombe was a powerful and determined opponent of abortion, euthanasia, and the intentional killing of noncombatants in war (even in justified war). In considering these questions, she drew on the resources of Catholic philosophy (she was a convert to the faith as was her husband, the distinguished philosopher Peter Geach) and the history of philosophy generally. Yet, she never hesitated to correct what she regarded as errors in traditional philosophical doctrines and ways of thinking or improve on ideas she drew from them. For example, though she did not dismiss the idea of “double effect,” as some philosophers of her generation did, she carefully analyzed and cleaned up the parts of what turns out to be a rather complex philosophical doctrine to show that whether an act counts as “intentional killing” is one thing, but whether the act is justified even if it can be shown to qualify as the unintended causing of death is something else.

Anscombe coined the term “consequentialism” (which she introduced in “Modern Moral Philosophy”) to name the view, widely held today even by people who reject the classic utilitarian identification of good with pleasure and evil with pain, that there is no act that cannot in certain circumstances be justified by its good consequences or by the bad consequences that would likely follow from not performing the act. Consequentialism, in her opinion, has proven to be a profoundly destructive force, not only in ethics considered as a field of academic philosophy, but in the ethical lives of individuals and cultures. The conviction that a little evil may rightly be done for the sake of a greater good, or for the sake of preventing a greater evil, puts human beings on the path to losing their grip on good and evil altogether. We would not have gotten those “liberal” abortion laws in the first place were it not for the widespread adoption of an essentially consequentialist view of right and wrong.

Interestingly, Anscombe had doubts about whether the early human embryo is a human being. Because in the very early stages of development the embryo can divide and give rise to monozygotic (“identical”) twins, Anscombe was puzzled by the exact status of early embryonic human life. She wrestles with the problem in two essays reprinted in the volume: “Were You a Zygote?” and “Embryos and Final Causes.” Never, though, was Anscombe tempted to conclude that abortion”even early abortion”can be justified. As Mary Geach quotes her, “even if it were certain that, for example, a week-old conceptus is not a human being, the act of killing what is in the earliest stages of human life has evidently the same sort of malice as killing it later on when it is unquestionably a human, or more than one.”

For my part, I don’t think the possibility of twinning creates the puzzle that Anscombe thought it creates, so I think the evidence shows that the embryo is from the beginning of its existence at conception (or, in the case of an embryo produced by cloning, with the activation of the enucleated ovum into which the nucleus of a somatic cell has been inserted) a human being. Indeed, Anscombe herself allows that the early embryo is a “living individual whole whose life is”all going well”to be the life of one or lives of more than one human being.” That’s certainly right. And this “living individual whole” is nothing less than a complete and distinct human organism possessing all of the genetic material needed to inform and organize its growth, as well as an active disposition to develop itself using that information. The direction of its growth is not extrinsically determined , but is in accord with the genetic information within it. The human embryo is not, then, something different in kind from a human being, nor is it merely a “potential human being,” whatever that might mean; rather the human embryo is a human being”a whole living member of the species Homo sapiens ”in the embryonic stage.

The fact that a human individual in the embryonic stage can divide or be divided into two individuals is no cause for doubting whether the individual is a human being. Consider the parallel case of division of a flatworm. Parts of a flatworm have the potential to become a whole flatworm when isolated from the present whole of which they are part. Yet no one suggests that prior to the division of a flatworm to produce two whole flatworms the original flatworm was not a unitary individual and a whole living member of the species.

In “Embryos and Final Causes,” Anscombe correctly observes that “the Catholic Christian Church has always objected to procuring abortion, but to this day has not adopted the doctrine of immediate animation.” But the reason the Church has so far held back from officially adopting this doctrine is not because of a puzzle about twinning. It is because until fairly recently in modern history we lacked the knowledge of embryogenesis and early human developmental biology to say securely what we now know with certainty, namely, that even the early embryo is a complete, self-integrating human organism that by directing its own integral organic functioning develops himself or herself to the next more mature stage of his or her life. We now know securely that the difference between an embryo and a fetus, infant, child, adolescent, and adult is not a difference in kind , but is rather a difference in biological maturity or stage of development. Embryos and human beings are not different kinds of beings; an embryo is simply a human being in the earliest developmental stage.

Anscombe’s “theoretical doubts,” as she called them, did not erode what she called her “practical certainties” about the need to respect and protect by law human life at all stages and in all conditions. Nor did they induce in her any willingness to tolerate the dehumanization of the child in the womb. I was once at a conference where the theologian Lisa Sowell Cahill objected to an analogy proposed by another speaker, Russell Hittinger, between slavery and abortion. Cahill said that African-Americans whose ancestors suffered the horrors of slavery could reasonably take offense at Hittinger’s comparing them to embryos. Anscombe, who was also in attendance, immediately intervened to say: “the lady should not say ‘embryo,’ but rather ‘conceived child.’”

Late in her life Anscombe and one of her daughters became active in the British equivalent of Operation Rescue. They got themselves arrested for blockading an abortion clinic in an effort to stop the abortions being performed there. She was in every way a practical philosopher.

Robert P. George is the Cyrus Hall McCormick Professor of Jurisprudence at Princeton University