I came across this webpage that has a chapter from a textbook called Developmental Biology by Scott Gilbert while looking in the comments section of a pro-choice blog. Gilbert is a professor at Swarthmore College.
I find this to be the oddest chapter in any biology textbook that I've ever seen. Instead of focusing on what science tells us about when life begins, Gilbert's chapter introduction asserts that, "A key point in the debate rests on the way in which we choose to define the concepts of humanity, life and human life. What does it mean to be alive? What does it mean to be human? Is a zygote or an embryo alive? Is a zygote or an embryo a human being? These are intricate philosophical questions that often incite intense debate, for their answers are used as evidence in the answers to questions about the moral status of a zygote, embryo or fetus.
"The question of when human life begins has been pondered throughout history and in a multitude of cultural contexts. The "answer" is fluid, in that it has been changing throughout history, because any answer about when human life begins is deeply integrated with the beliefs, values and social constructs of the community or individual that drew the conclusion. Throughout history there have been several "answers" to the question of when human life begins, but the only consistency among the answers is that they are always changing as social contexts change, religious morals fluctuate, or new knowledge about the process of embryo development is obtained."
For an embryologist to claim that when something is alive or what species it belongs to are questions for philosophy shows me that a certain embryologist has allowed his philosophical and political views to undermine his scientific work. Who really thinks that whether an organism is a rat or a human or a amoeba or a duck is a question for philosophy? Who really thinks that whether a human being is alive or dead is a question for philosophy?
Gilbert's drafty logic seems to be that because various cultures with no to very little scientific knowledge about fetal development had differing opinions about when life begins that therefore the "answer is fluid" and not some how attainable through science.
It is also extremely odd because the first paragraph of Gilbert's book says, "Between fertilization and birth, the developing organism is known as an embryo. The concept of an embryo is a staggering one, and forming an embryo is the hardest thing you will ever do(emphasis mine)." Gilbert then goes on to explain how difficult it is for you to build yourself.
How can a developing organism possibly not be alive? How can an organism that is growing and developing itself somehow not be alive? Do things that aren't alive develop? Don't we have to be alive to grow and develop? How can you be a human being now but at some prior point in your development be something other than a human being. It makes absolutely no sense. Gilbert is well aware that embryos are alive and that human embryos are in fact human beings.
His "When Does Human Life Begin" chapter then examines the views of a variety of historic cultures regarding abortion and how those views influenced their perception of when life begins or vice versa (Gilbert never explains why the opinions of ancient people with extremely little scientific knowledge about embryology is important). After that Gilbert examines how different "scientific" perspectives vary on when life begins and asserts that "contemporary scientific literature proposes a variety of answers to the question of when human life begins."
The first view Gilbert examines is the metabolic view. He cites no scientist that holds this view which isn't surprising because this view holds that "Both the sperm and egg cells should individually be considered to be units of life in the same respect as any other single or multicellular organism." Only a complete quack of a scientist would actual believe egg and sperm cells (parts of larger organisms - like hands, fingers, toenails, etc.) should be given the same respect as whole organisms.
The second view that Gilbert examines is the genetic view which is actually a scientific position that he summarizes as, "The genetic view takes the position that the creation of a genetically unique individual is the moment at which life begins." Gilbert, however, seems to not like this view because he raises numerous philosophical objections (something he doesn't do for most of the other views).
He continues with the embryological view which "states that human life originates not at fertilization but rather at gastrulation. Human embryos are capable of splitting into identical twins as late as 12 days after fertilization resulting in the development of separate individuals with unique personalities and different souls, according to the religious view. Therefore, properties governing individuality are not set until after gastrulation." This is a philosophical view loosely based on science not a scientific view. If something is developing how is it not alive? If adult humans had the ability to twin, would that mean that we weren't alive until that ability ceased? Are flat worms not alive because we can cut one flat worm in two and get two flat worms?
Gilbert then summarizes a couple more philosophical views (which I might get to later - this post is long enough) which he labels scientific views and then summarizes one view that he actually admits is philosophical (self-consciousness makes us human beings).
Gilbert concludes by saying, "However, understanding the basis for societal moral standards appears to be the key to discerning how to approach the question of when human life begins. Science has not been able to give a definitive answer to this question.....The moments of fertilization, gastrulation, neurulation, and birth, are then milestones in the gradual acquisition of what it is to be human. While one may have a particular belief in when the embryo becomes human, it is difficult to justify such a belief solely by science."
How is this a science textbook? When life begins is a matter for societal moral standards? What an assertion! Questions of what something is biologically aren't questions for philosophy or sociology, they are obviously questions for biology. It seems that Gilbert doesn't like the answers that biology has given him and has allowed his political opinions on abortion to influence his writing.
I will try to write later about Gilbert's cheap shots at prolifers (he calls us anti-abortion activists) and the use of images of unborn children in the womb.
UPDATE:Serge has beaten me to the punch.