"Firstly : the statement you are trying to support is `` Biologically speaking , a human individual 's life begins at conception `` . However , the word 'life ' - that which you are arguing has a factually determinable beginning , does not have an absolute biological definition . To quote the wikipedia article on it : `` It is still a challenge for scientists and philosophers to define life in unequivocal terms `` . This is doubly the case when considering the 'life ' of an individual , as opposed to the 'life ' of , say , a skin cell . For example , a person with no brain activity can be composed of living cells if they are kept on life support , but legally and medically the individual is considered dead . The argument , then : If 'life ' has no definitive definition , how can you argue that it has a clearly definable start ? Secondly : Consider a zygote . According to you , it is an individual . But a zygote can split into two - to form monozygotic , or 'identical ' , twins . Before splitting , it is one 'individual ' . Afterwards , it is two . Where has the extra individual come from ? Given that the split can happen up to 15 days after fertilisation , when was the start of that individuals life ? Thirdly : In contrast to identical twins , consider a chimera organism . A chimera is made up of cells containing one of two different strands of human DNA - they are formed when two fertilised eggs or early embryos collide and become one embryo , which then goes on to be a single human being . Given that the single individual was created by the merging of two different individuals ( by your definition ) , when was the biological start of their life ?"
"I 'll take these questions ( one at a time ) in the other thread ."
"Firstly"
"I 'll take these questions ( one at a time )"