In another respect a two month old baby is not *viable*. He'll starve unless food it put directly into his mouth, he can't clothe itself to protect himself from the elements, can't defend himself from attack, and can't move from one place to another without being picked up and carried. How *viable* is that? Where does one draw the line?
> In another respect a two month old baby is not *viable*.
Sure he is, unless you left him poutside on the lunar surface. A two-month old baby is generally in a perfectly normal environemtn for a two-month old baby. But a sperm and an egg doign their little dance in a test tube... this is *not* normal, and the result of their union is *impossible* to be viable without direct *technological* intervention. Feeding a baby is a perfectly natural sort of thing to do. Using a pipette and a microscope to scoop up a few cells and then implant them intop a womb is *not* a natural sort of thing. It's the sort of thing that would *never* occur by way of instinct or low technology.
> Where does one draw the line?
In this case? When the embryo is put into it's natural environment. But an embryo in a test tube is as viable as *you* stand buck naked on the surface of Mars with nothing but a scuba tank and a wool blanket.