Much of the abortion debate rages over sophisticated biological terms like gamete, sperm, egg, haploid, diploid, embryo, fetus, zygote, conceptus and so on. One should be careful however not to let the terms slip from distinctly human debates–to other animals. That is, biological and legal precision merit careful terminology that does not intentionally cloud otherwise clear concepts; in particular, the issue is over human embryos and human fetuses and human zygotes not over indistinct a-speciated embryoes, fetuses, and zygotes. This terminological care is important for several reasons.

First, the abortion debate, as the phrase is normally used, is not raging over other animals but over human beings (i.e., members of the species homo sapiens).

Second, whatever one may say about speciesism, there remains a widely recognized legal (and perhaps moral) difference between killing a non-human animal and killing a human being.

Third, it risks intentional ambiguity (which is ethically questionable) to opt against saying “human fetus” or “human embryo,” and instead say “fetus” and “embryo” when those terms apply equally to horses, pigs, dogs and cats in their respective developmental stages.

Fourth, vague and indistinct terms risk blurring matters worse than they already are. For the sake of ethical and legal clarity one should remember, in the course of this poignant debate, that one is never talking about a mere embryo, fetus, zygote, blastocyst, etc. One is talking about members of the human species, which are biologically identifiable as genetically distinct living human organisms of the species homo sapiens.

But what is this supposedly “precise” clarifying term: “human”? One could venture deep into existential and philosophical explorations on this loaded question, but much of that is unnecessary for this simple point. “Human” is the adjectival form or abbreviated nominal form of “human being,” and that, at minimum, indicates a organism which is a member of the species homo sapiens.

Technically speaking, gametes, like sperm and eggs, are not human organisms in the same sense as a conceptus since the sperm and egg cannot conduct the full functions of biological life such as digestion, growth, reproduction, and excretion. They do not, therefore, constitute a stage of human development since they are precursors to the first stage of a genetically distinct living human organism, occurring at fertilization. Gametes are more like organs or organelles in that they conduct a function of life for the larger organism but are not themselves organisms.

A lot goes into the weighty word “human.” Ethicists, politicians and philosophers alike would do well to acknowledge its force and be careful not to obscure, blur, or neglect it where it truly applies to individuals.