It's an old game but play it with me anyhow.

Three people go to a restaurant for a quick snack while attending a conference. They order a special plate which was supposed to cost them $10.00 each.  When the food arrives it's not the way it was shown on the menu and they complain.  Their order taker takes the complaint to the manager and the manager agrees to take $5 off of their $30  bill.  The order person figures it's easier to just give $1 each and pocket the extra $2 instead of making change, and that's what happens.

So they paid $9 each for the food. $9X3 = $27 - the order taker kept $2 = $29 Where did the extra $1 go.

What we have here is what appears to be a mathematical logic problem and what we also have is a demonstration of a philosophic method called Sophistry.

It appears to be logical but either some of the information provided is false or the question asked has no real meaning in terms of the information provided.  It's essentially a word game.

That is exactly what the "when does life begin" question is about.  

The question really has no meaning and there is no answer.  As has been consistently pointed out with respect to this question  - the spermatozoon is alive, and the oocyte is alive, so life already exists before conception.  Furthermore that life has existed as a part of a continuum going back to the first Homo Sapiens Sapiens.  When you're dealing with a continuum any point on that continuum could be chosen as a starting point and any point could be justified as "THE" starting point.

We could easily claim, for example,  that the point where the diploid oocyte is penetrated by the spermatozoon and completes cleavage permitting a new diploid cell called a zygote to form is the starting point. We could claim that when the autosomes line up with each other forming chromosomes THAT is the beginning point. The spermatozoon contains the trigger that will "turn on" the placental formation so that point cold be called a beginning. We can continue through the beginning of embryonic / placental specialization of basic stem cells in the developing blastocyst so that some will be placenta and some embryo; implantation; "quickening" or the first detected movement; viability; self supporting ex-utero viability; and birth - all of which are considered defining and essential moments in the human, or any mammalian, reproductive cycle.  If we're talking about an In Vitro Fertilization we might claim that when the pre-embryo 'defrosts' life begins.  Every one of these could legitimately be considered the beginning point for personal life - depending on what your political or religious reason for making the claim is.

So if they're all legitimate beginnings then the question "when does life begin" really has no legitimate answer?  

However we all know something starts at conception, and whatever that is it results in an offspring if it's successful.  So what DOES start at conception?

The obvious answer is the *process* that leads to a new individual offspring and that process is called reproduction.  In humans the gestation or the reproductive cycle is approximately 40 weeks in duration and begins at conception.  We really don't have a "just add autosomes and "'POOF' instant baby" process but we have a process that continues in normal circumstances for a duration of 40 weeks.

So the Sophistry is the claim that "life begins at conception". That's the "poof - instant baby" idea, and not the 40 week process which is the reality. By asking the right question and looking at the right information you get the right answer.

For those who claim science can answer the question we might remind them that science, in the last 25 years, has certainly made some remarkable discoveries - but unfortunately when personal life begins is not one of them. If it was,  then there would be no need for this essay. The answer would be written in all the science texts, not discussed in the philosophy texts the way it is today. There would be no disagreeement on the facts - just as there is no disagreement on the number of chromosomes a normal human has (I qualify this with "normal" because there are humans with 45 or 47, and even 48 chromosomes, but this is not considered normal, as is 46 chromosomes.)

"When does life begin?" is the wrong question.  The question we want answered is "at what time in the reproductive process has the developing offspring attained enough growth to be entitled to the rights of membership in our society."  For millennia the answer to that question has remained unchanged - it's birth. This point has been chosen for a number of reasons. It is readily visible; the developing offspring is no longer a part of the woman; and as a member of society, the society is capable of caring for it from that point. Birth is the proof that the process has been successful and is finished.

Reproduction begins at conception!

If you didn't figure it out the order taker's $2 is included in the $9 they paid - and they each got $1 back.

Eileen

I originally answered this question by rebutting the essay of Libertarian philosopher, Dianne N. Irving, since that is a frequently quoted Abortion Opponent "proof" of the claim that "life begins at conception".  That essay is available HERE