Size, development, location, dependency, the four tests that exclude no one

Here is a test for any principle that claims to say who counts. Apply it to yourself. If the principle would have excluded you at some point in your life, or would exclude you after a bad accident, you should wonder whether it is a principle or merely a convenience.

Most arguments about the worth of the unborn turn on a list of differences. The unborn child is smaller. She is less developed. She lives in a different place. She depends entirely on her mother. Each statement is true. The question is whether any of them is the kind of difference that can decide whether a human being has a right not to be killed. A philosopher named Stephen Schwarz gave that question an organising structure thirty-odd years ago, and it is still the cleanest way to put it.

The claim

In The Moral Question of Abortion (Loyola University Press, 1990), Stephen D. Schwarz argued that every difference between an unborn child and a newborn, or between an unborn child and an adult, falls into one of four categories. He abbreviated them SLED: size, level of development, environment and degree of dependency. His claim was that none of the four is a morally relevant difference of the kind that can justify killing, and that together they exhaust what distinguishes the unborn from those we already protect.

Let me define the terms carefully, then number the argument.

Size means physical dimensions. Level of development means the degree to which a human being has developed her capacities and organs: an embryo has fewer than a toddler, and a toddler fewer than a teenager. Environment means location: inside the womb or outside it. Degree of dependency means reliance on others for survival: the unborn child depends wholly on her mother's body, the newborn on caregivers, the adult on far less.

The argument is a challenge. Name a difference between the unborn and a person already born that is not in one of these four categories, and that could justify the claim that the one may be killed and the other may not. If you cannot, then the question becomes whether any of the four can bear that weight.

The premises

One. Killing an innocent human being is wrong unless some morally relevant difference justifies it.

Two. The differences between the unborn child and a born person fall into four categories: size, level of development, environment and degree of dependency.

Three. None of these four is a morally relevant difference that would justify killing, as the tests below show.

Four. Therefore the difference between the unborn and the born does not justify killing the unborn.

Premise one is nearly universal, and the pro-choice position does not usually deny it. The dispute is mainly about premise three, so let me apply each test.

Test one: size

Is a smaller human being worth less? Take it seriously for a moment. A newborn is smaller than a toddler, a toddler smaller than a teenager, and the teenager smaller than the professional athlete who is seven feet tall. If size determined worth, then the tall would have more rights than the short, and a full-grown man of average height would have less claim to protection than a giant. Nobody believes that. We do not measure the right to life by the tape measure. Size varies among adults by a factor of two or more, and no one proposes that the shortest adult may be killed to spare the inconvenience of a taller one.

The point is not that size is irrelevant to every question. A large animal weighs more than a small one, and that matters for building a bridge. But it has no bearing on whether a creature is the kind of being who may not be killed. A difference that does not matter among adults cannot suddenly matter between a child and an adult.

Test two: level of development

Is a less developed human being worth less? Here the argument is subtler, because development is a matter of degree and it takes obvious forms. A fetus at eight weeks has not developed lungs that work or a mind that reasons. But apply the test to the born. A newborn cannot walk, talk, reason or recognise herself in a mirror, and a toddler cannot do arithmetic. A person with a severe cognitive disability may never develop what a typical adult has. A teenager's brain is not fully mature in the way an adult's is. If degree of development determined worth, the newborn would have less than the toddler, the toddler less than the teen, the teen less than the adult, and the adult with a developmental disability less than every other.

What follows is a ranking of human worth by capacity, and it conflicts with the claim at the heart of the American tradition. The Declaration says all men are created equal. It does not say they are created equally developed. The equality it asserts is of a kind that does not vary by degree.

The reply is to say that what the unborn child has is a potential to develop, and potential is different from actual capacity. Let us hold that thought, because it is the heart of the strongest objection, and I answer it below.

Test three: environment

Does a change of location change what a being is? Consider the moment of birth. A child at thirty-nine weeks in the womb and the same child an hour later in a hospital nursery differ in where they are, how they breathe and how they are fed. They do not differ in what they are. If a trip down the birth canal confers rights, then the whole moral weight of the question rests on a few inches of travel, and it is hard to see why that would be.

The same applies elsewhere. A baby in an incubator is in a different environment from a baby in a crib, and nobody thinks the incubator baby has less worth. An astronaut in orbit is in a very different environment from a citizen at home. A person in a hospital is in a different one from a person in a house. Location can change what is done to a person. It does not change what a person is. This is the reason that the law, in the matter of born-alive infants, treats a child who survives an attempted abortion as a person entitled to care, a point explored in The Born-Alive Infants Protection Act of 2002 and what the law requires. The child's rights do not wait on her address.

Test four: degree of dependency

Is a more dependent human being worth less? This is the test that makes the argument bite, because the unborn child is wholly dependent on her mother's body. The reply asks us to look at who else is dependent. A newborn is dependent on others for everything for years. A person on dialysis depends on a machine and a medical team. A man on a ventilator depends on a device. A patient in the middle of a long surgery depends wholly on the surgeon and the anaesthetist. An elderly person who cannot feed herself depends on a caregiver. If dependence were a ground for losing the right to life, we would have to say that the most dependent have the weakest claim, which is the reverse of what a moral society holds. We tend to say that a greater need is a stronger claim on the community, not a weaker one.

Dependency is where the strongest version of the bodily-autonomy argument enters, since the unborn child depends on one person's body in a particular way. I have argued elsewhere, in the famous violinist argument for abortion, and why it never fit the case, that the analogy does not carry the weight placed on it. Here the narrower point is enough: dependency as such does not make a being less worthy of protection. If there is a case about the mother's body, it is a different case, and it has to be made about the mother's claims, not about the child's worth.

The strongest reply: sentience and personhood

Now to the best case on the other side, which I owe the reader. Defenders of abortion choice who think hard about the matter do not usually say the unborn child is worth less because she is small, or in the womb. They say something more careful: that the right to life belongs not to every member of the human species but to persons, and that being a person requires a certain kind of mental life.

Several philosophers have developed the view. In 1972, Michael Tooley published "Abortion and Infanticide," arguing that to have a right to life, a being must be capable of desiring its own continued existence, which requires a concept of itself as a continuing subject. In 1973, Mary Anne Warren, in "On the Moral and Legal Status of Abortion," listed traits central to personhood: consciousness, reasoning, self-motivated activity, the capacity to communicate and self-awareness. On these views, an early embryo, which has no consciousness, is not a person. A fetus becomes one, or approaches it, at some later stage that depends on the theory, often tied to the development of sentience, the capacity to feel.

This view should be taken seriously, and it differs from the crude versions of SLED. It does not say that a smaller person is worth less. It says that what makes any of us matter is the mind, and the unborn child, for a time, has none yet.

The answers to the reply

Here is why I think the sentience and personhood view fails, in four points.

One: it proves too much, and its own authors admit it. If the right to life depends on self-awareness and a concept of oneself as a continuing subject, then a newborn does not qualify, and neither does an infant of several months. Tooley accepted this conclusion and defended infanticide in his 1972 paper. In 2012, Alberto Giubilini and Francesca Minerva published an article in the Journal of Medical Ethics entitled "After-birth abortion: why should the baby live?", arguing that the same reasoning justifies the killing of newborns. Most people, including most defenders of abortion rights, recoil from that conclusion. The reaction tells us something. When a theory of who counts requires us to say that a newborn does not, the likelier explanation is not that newborns have no right to life but that the theory is wrong.

Two: capacity and the possession of it are different. A sleeping adult is not conscious. A person in a reversible coma has no present mental life. A newborn's self-awareness is rudimentary. Yet we say that all of them have a right to life. The answer given by philosophers such as Patrick Lee and Robert George is that what matters is a basic natural capacity, a root capacity for thinking, deliberating and choosing that a human being has from the start because of the kind of thing she is, even when it is not yet exercised. The unborn child is not a thing that may become a human being. She is a human being at an early stage. A thing that has a nature that includes the capacity for reasoning has it even when the capacity is undeveloped, interrupted or impaired.

Three: any threshold of function creates a ranking. If personhood depends on mental capacities, and capacities come in degrees, then personhood comes in degrees, and some human beings are more of a person than others. A genius has more than an average adult, an average adult more than a person with advanced dementia, and the very young and very old have the least. A criterion that ranks persons cannot support equality. The Founders were clear that equality rests on a nature that all human beings share and not on talents that vary. Nothing in the Declaration's phrase "created equal" makes exceptions for the less able. That is why Why 'created equal' is a claim about God and not just about politics presses the point that equality has to rest on something deeper than ability.

Four: the line is arbitrary where it is drawn. If sentience matters, when does it begin? The theory does not say, and its defenders disagree. If the answer is "later than the point at which most abortions occur," then the theory is defending present practice without a principle to justify it. A line that moves to wherever it is convenient is a policy and not a moral criterion.

What it means in law

Our law has not always protected every human being, and the failures are the best argument for the principle. In Dred Scott v. Sandford (1857), the Supreme Court held that the descendants of people brought to America and sold as slaves were not citizens, and described them as a class with "no rights which the white man was bound to respect." The decision rested on the same logic of exclusion by category, and its legacy is explored in Dred Scott, Roe and the danger of a Court deciding who counts as a person. The Fourteenth Amendment answered it by forbidding any state to deprive any person of life, liberty or property without due process, and to deny any person the equal protection of the laws. The word is person, and its meaning was meant to be wide.

The pro-life argument is that no test of size, development, location or dependency can be used to cut a human being out of that word, and that a republic founded on equal dignity cannot make the dignity of one person depend on the ability of another to be heard. The answer of those who disagree is the personhood account above, which deserves a hearing. In the end the matter is for a free people to settle by argument and by vote. It is the argument that makes the vote worth having.

A note on persuasion

Let me add a word about how to say this. The test works best when it is put as a question and not a charge. A person who disagrees is usually not a monster but someone who has not seen the question laid out this way, or who has seen it and has a reason of her own. The point of the four tests is to show what we would have to accept if we used them, and the best way to do that is to invite the other person to find a test that does not exclude anyone she cares about. That is an argument, not a shout, and it is the kind that wins slowly and holds.

The case in brief

1. Stephen Schwarz's SLED argument holds that every difference between an unborn child and a born person falls into four categories: size, level of development, environment and degree of dependency.
2. Applied to born people, none of the four decides whether a human being has a right not to be killed, since the short, the undeveloped, the hospitalised and the dependent are all protected.
3. The strongest reply, from sentience and personhood theorists such as Tooley and Warren, locates worth in mental capacities, but it excludes newborns, as its own authors have admitted.
4. A threshold based on capacity ranks human beings by degree, which cannot support the equality the Declaration asserts or the equal protection the Fourteenth Amendment guarantees.
5. A republic founded on the claim that all are created equal cannot make the dignity of any person depend on ability.

What you can do: take the four tests to a friend who disagrees, ask them to name a difference that does not fall into one of the categories, and listen to the answer.