and why?

life medically speaking or life form our point of view (like our first thoughts, needs, feelings, actions) ?

life as in a new individual's existence

How is it relevant? Individual existence is unproven you cant expect for someone to tell you when does it start :)

What we do know that there is a time without neural activity within an embryo, it is effectively 'dead' in cognitive sense, it doesnt 'tick' yet, but if you ignore the transition from non-sentient to sentient and just go with biology, 'life' starts at conception when a new DNA code is formed...

If you say that "life" starts at conception (ie: sperms enter the egg), then how do you explain identical twins? where the zygote divides into two AFTER the sperm enter the eggs.

Define 'life' in a way that it doesn't start at conception, other than arbitrarily assigning uniqueness to it.

If you use a term you have to explain it or these threads will just get stuck in language... if your 'life' is a philosophical term then tell us its qualities so we can give at least half-informed opinion :)

I think life begins in the first trimester...

Earliest form is a fetus with working neurons, and it comes to be by following conditional DNA replication like good little bio-machine, there is no great leap from a lump of biomass to 'new individual', we just put the algorithms in loop and get more complex as we build up... no 'life' in any philosophical sense we just become complex in our reactions to environment, 9 week old fetus can hear, it is not a 'someone' but it can taste, or display reaction or even habituation to stimuli.

Surely man is not capable of creating life.
but man creates fertilized cells, without sperm, without any genetic link to the donor of the egg, so what does man do then? Either DNA is life in itself, waiting to happen, a possibility of life or at some point a bio-machine created by DNA enables some unexplainable force to enter our world and control its existence, creating a tiny shiny portal in uterus through which angels descend the soul into a lump of biomass :P Occam's razor is a dirty word ain't it :)

You're straying off topic... so according to you, the fetus is when "life" begins?

So does that mean first trimester?

How should i know? I have no idea what is the extra quality that separates 'life' and mere 'existence'... if its higher brain function, then yes, its 1st trimester, but its just a convenient way of saying 'we agreed so' and its 'prevalent medical opinion'

I'd stick with conception for now because DNA is information, contains all the 'quality' needed for whatever 'life' is, everything else till the moment we die is 'quantity' more cells, more interconnections, more information...

If you still stick with at conception, that means a new "life" begins when the sperm enters the egg; then how do you explain identical twins (ie: two new lives) existing AFTER conception - at the stage where the zygote divides into two.

The fact of how identical twins are formed implies that "life" cannot begin at conception (sperm enterring the egg).

Unless you claim that identical twins are pre-determined when the sperm enters the egg (ie: specific sperm and specific egg), and not by random chance.

its a probability, some genetic lines are prone to twins, hell we can 'make' identical twins, cloning of the fertilized egg has been around for a while... it just means that you can copy 'life' and give it another instance in different settings...

I don't understand you triss. Why does the fact of how identical twins are formed neccesarily imply that "life" cannot begin at conception? Why? Just because that zygote divides in two? So you wanna say that a lifeform can't devide forming new life?
We make it in a similar way as the zygote. We give a bit of us to form another life from ourselfs. The babies are not exact copies of us (like the identical twins), but are a combination of the two parents.

Quote:

I already did define "life"... as... a new individual's existence... like you, me and everyone else... just at its earliest form

I still don't get it... Maybe if you'll answer me which of the following you consider to have "life" (or be alive) i can better understand what you want:
human baby
dog
ant
Taenia
cell
dna

Basically if you believe that "life" begins at conception then the existence of identical twins shows that "life" ALSO begins AFTER conception.

The two of them have a time line difference so it is not possible to have both to be true.

But the 'life' already started with formation of DNA what is it in your concept of 'life' that makes you think life is singular? It can be split, altered, copied, it does not 'start' in a true sense at any time other than the 'first life', its is a reiteration or recombination of the same DNA code that spent time running in a previous generation, the only thing about 'us' that has a 'start' is the formation of 'our' DNA code, the enviromental factors are there even at conception they dont just start influencing your 'life' at an arbitrary point in time after the formation of DNA, they are there before it, they influence the conception itself, there is nothing to us but DNA and enviroment, and enviroment is pre-exisiting...

I'm lost... are you saying that each cell (every cell contains full set of DNA) is a "life"?

In other words, in my body, there are John, Mary, Joe, Linda, or whatever other popular names, etc... "living" inside my body?

I thought we were at human life...

So by me the life ( as in experiences and casual day by day activities) starts at the first trimester cuz the fetus begins to eat which is a everyday activity and experience.

Slap... don't run away now; it's not an argument. I just fail to see what you are trying to say.

Well then, its my fault and we'll leave it at that :)

When does, in your opinion, 'life' begin ?

I have a different perspective on "life" and "death". To me, there is no beginning or end of a "life". They are periodic stages just like the rising and the setting of the sun. Because a sunrise differs depending on where you are on earth; therefore, there is not an absolute beginning of a sunrise nor sunset.

If the sunrise is defined as the first ray of sunshine hitting the earth, then the beginning of a "life" can be defined as the first cell that contain the full set of 46 chromosomes that can replicated itself. This is often called the forming of the zygote. However, since identical twins can still form at this stage; I'd prefer the beginning of "life" as an embryonic fetus.

Philosophy-wise, I do not believe there is an absolute beginning and ending of a "life". However, birth does have a beginning, as well as death does have an ending.

I refrain from arguing as your views are completely benign and generally acceptable

You can always try with my philosophical view

Nope, all out of steam, just realized i spent more time typing than i spent in any game during last week. I have a self-diagnosed COD when it comes to pointless arguments and i practice catching myself early on so i can just stop :))