Fuzzy Logic & Fuzzy Life
The following essay on the politically-charged issue of abortion was originally written for my regular Scientific American monthly column, Skeptic, but we decided that it was too political and not grounded enough in science for Scientific American, so we shelved it. I ended up expanding that column into a chapter section in my book The Science of Good and Evil.
In 1959 astronomers were polled for their opinion on the then undecided debate between two competing cosmological theories. “Did the universe begin with a Big Bang several thousand million years ago?” A third answered yes. “Is matter continuously created in space?” Almost half answered yes. Most telling, to the question “Is a poll of this kind helpful to scientific progress?” all answered no.
The reason for this unanimity is that scientific questions are not settled by consensus opinion. Unfortunately, in complex human and social issues, separating fact from opinion is not so easy, and for no issue is this more apparent than abortion. Setting aside the emotionally charged moral and political aspects of abortion for a moment, how can science inform this debate?
At the core of the moral and political question of whether or not aborting a fetus constitutes murder is the scientific question of when a fetus becomes a human being. Supreme Court Justice Harry A. Blackmun, writing for the 7-2 majority ruling in the 1973 Roe v. Wade decision, concluded: “When those trained in the respective disciplines of medicine, philosophy and theology are unable to arrive at any consensus, the judiciary, at this point in the development of man’s knowledge, is not in a position to speculate as to the answer.”
The problem is one of logic, not knowledge. Legal and political decisions are grounded in binary logic in which unambiguous yeses and noes determine final Truths. The law must make a determination on a case, a hard and fast ruling by which we are to abide. And political issues are settled by a consensus process called democracy. By contrast, science is grounded in fuzzy logic in which ambiguous probabilities determine provisional truths. Error bars accompany data graphs, p (probability) values are designated in decimal percentages indicating the likelihood of chance accounting for the finding, and caveats and cautions are sprinkled throughout conclusions.
In the abortion debate here is how the difference between binary and fuzzy logic plays out. Most Pro-Lifers believe that human life begins at conception — before conception not-life, after conception, life. Binary logic. Binary life. With fuzzy logic we can assign a probability to human life — before conception 0, the moment of conception, .1, multi-cellular blastocyst, .2, one-month old embryo, .3, two-month old fetus, .4, and so on until birth, when the fetus becomes a 1.0 human life form. Fuzzy logic. Fuzzy life.
The process does not sound very romantic, but from a scientific perspective human life is a fuzzy continuum. Neither egg nor sperm is a human individual, nor is the zygote or blastocyst because they might split to become twins, or stop developing and naturally abort. The eight-week old fetus has recognizable human features such as face, hands, and feet, but neuronal synaptic connections are still being made so thought is not possible. Only after eight weeks do embryos begin to show primitive response movements, but not until seven months does the fetus develop sufficient neocortical complexity to exhibit some of the cognitive capacities typically found in full-term newborns (in between, the fetus may respond reflexively to stimuli but this in no way can be construed as sentience). Fetus EEG recordings with the characteristics of an adult EEG appear at approximately 30 weeks. In other words, the capacity for human thought does not exist until just six weeks before birth.
Autonomy is also an issue. Between two and six months the fetus could not exist on its own because such critical organs as the lungs and kidneys do not mature before that time. For example, air sac development sufficient for gas exchange does not occur until at least 23 weeks after gestation, and often later. Since virtually no abortions are performed after the second trimester, and before then there is no scientific evidence that the fetus is an autonomous thinking human individual (most scientists agree that of all the characteristics used to define what it means to be human, the capacity to think is the most important), the case for abortion as murder cannot be based on scientific grounds.
Unfortunately, fuzzy thinking often prevails over fuzzy logic, where morality, politics, and science are confoundedly conflated. Moral issues are personal. Political issues are social. Scientific issues are factual. Pro-Choicers believe that whether a woman decides to abort a fetus or not is a personal moral issue. Pro-Lifers want to make it a political issue in which society makes that choice. The fuzzy logic of science reveals that there is no consensus on when a human life begins because it unfolds along a quantitative scale. Therefore, although one may oppose abortion for personal reasons, there is no scientific justification to shift the abortion issue from the personal to the political.
This article was first published here.