DM said:
A zygote is a human life form constituted from two parties. It has ABILITIES to develop into a human being.
Yes, but exactly the same can be said about a T-cell (white blood cell).
I want to point out to the arbitrariness of the definition: constituted from TWO PARTIES, human life form, the ability to devellop.
Against each individual criterium, I can find an obvious counter example:
*) Constituted from two parties: admit that this is a priori a silly criterium: why should human rights be based upon the origin being from two parties ? But ok, let's accept it. Assume now that I CLONE a human being, by extracting its DNA, say, from a T-cell of yours, and putting that DNA into another egg cell. There is no a priori reason why this is not possible; it has been done with sheep. Does that mean then that the grown-up person that would result from such a manoeuver would not have any human rights, it being only the result of ONE party ? I'm sure that if that person grows up like a healthy boy of 15 years, which is biologically your twin, you would not like to deny him its human rights, would you ?
*) human life form: the definition of a human life form must be a cell, containing human DNA in its core. Your T-cells satisfy the definition.
*) the ability to devellop into a human being. Note that by this, in itself, you are already admitting that it IS NOT YET A HUMAN BEING ! But ok. I can take this in several ways. An unfecondated egg cell can devellop into a human being, for instance, I can take DNA from the mother, and put it in its core, and then it will devellop into a clone of the mother.
If it is the DNA that counts, then I can take the DNA of a T-cell, and that DNA, when put into an egg cell, can also devellop into a human being. So in a way, T-cells, when put in the right "environment" can also devellop into human beings.
But there's another way of seeing this: if whatever has an ability to devellop into a human being should do so, then unfecondated egg cells and spermatozoida should always be put as much as possible into contact, because every way of not doing so would deny that potential human being from develloping. In other works, one should deliver oneself to fornication all over the place until exhaustment
because NOT doing so would deny the right of development of POTENTIAL human beings.
Apart from these difficulties with your definition of what has human rights:
You can of course improve the biological definition of whatever has to have human rights until there's nothing left but a zygote that satisfies it. But admit that this is totally arbitrary: you are ADAPTING your definition of what has human rights IN ORDER TO ARRIVE at your desired conclusion: namely zygotes. There's nothing NATURAL about it, and I can now try to have you argue WHY the definition you gave should imply the acquiring of human rights. You will have a hard time.
A much more natural definition would be: "when there is the potential for conscious human suffering present", because it is based upon an ethical rule that one should not make other humans suffer consciously.
Or "when it can devellop biologically ON ITS OWN into a human being". This is more based upon the fact that "you own your body" and that you have the right to deny other beings of using it.
These points are discussable. Not a definition made up to arrive at a zygote, in order to give some scientifically sounding background to a purely religious idea.
So again, apart from the above counter examples to each part of the definition, what ETHICAL reason is there that justifies such a definition which is not based upon a religious argument ?
, but that shouldn't matter when discussing what is to be legal and not FOR OTHER PEOPLE. The separation of religion and state has exactly this as its foundation: religion cannot be used to argument any legal rule. You are FREE to your religious opinion, but you are NOT FREE to impose it upon others. So all reasoning leading to a law should be free of religious arguments, but solely based upon scientific and logical arguments. It is exactly this lack of separation which is the total disaster of theocracies.