You argued it but failed to explain why implantation before sufficient development occurs should be used to determine whether or not it's a distinct biological organism.
If you're arguing that the fetus/tapeworm has structural integration with the host, yes they do.
My position is that the fetus is not biologically part of the mother’s organism, but is part of her structurally. I'm still confused by this statement that you made earlier:
Why would structural attachment determine whether or not something has a life (both philosophically and biologically)? Using your logic under the
violinist thought experiment, the violinist and the person he attached to would have to be considered one person, living a single life, the moment the attachment is performed. However, this clearly makes no sense as both the violinist and the person remain distinct individuals with their own lives even though one depends entirely on the other for survival. The same principle applies to conjoined twins: their physical attachment do not turn them into one life. Physical attachment is not a merger of lives into one.
Furthermore, you also cannot argue that certain body parts belong to the violinist while others belong to the person he is attached to, because if they shared one life, there would be no meaningful distinction/ownership between their bodies.
My entire argument is that, if you are physiologically dependent on the parental organism for development, you are physiologically part of that organism. It's not about structural integration. It's about the fact that it is literally physiologically or biologically dependent for survival on a parent organism and will die if detached.
Remarkably, by the time there is potential for a fetus to demonstrate conscious mind, it already has the potential to demonstrate separate breathing of a separate organism from the parent. So having a life of one's own and having a mind of one's own seem related.
I won't use a comparison with an exemplar of a parasitic species because, here, the exemplar is separated from a parent organism physiologically or biologically and is surviving on an organism of a completely different species and not a parent.
As for conjoined twins, their problem is that they are not physically attached to each other, but that there is one seamless physiological organism and, if you want there to be one body for each, you have to separate them physically. We do that when there are two separate minds because minds are the basis of persons.
In my philosophy, the embryo and woman are technically originally separate, but the embryo would die if it didn't implant into the woman's body and stay implanted. The violinist and the other are originally separate, but the violinist would die if it didn't implant into the woman's body and stay implanted.
But the woman and the other don't need the embryo and the violinist to live - if they die, the woman and the other will go right on living anyway, because they don't need an infusion from someone else's life to continue living. And that's how you know that the life involved here is the life of the woman, not the embryo, or of the other, not the violinist.
As for the conjoined twins, theirs is a different case, as there really is only one body with two minds, and whether or not they can each get a separate body depends on whether there are enough body parts. For example, there may be only one heart shared or the separate breathing of each travels down to only one pair of lungs. But at the same time, if only one head is functional, the other parasitic, the latter can be removed for the well-being of the person represented by the functional head.
I have explained the issue of a true parasitic species exemplar above. A human embryo is parasitic only on a parent, and a human neonate is no longer parasitic but completely differentiated from its parent. A tapeworm is comparable to a neonate, for it is not parasitic on its parent.