The opposing sides of the abortion debate rely on arguments something like the following
Anti-Abortion: A human fetus is a human. Abortion kills that human. Killing is wrong. Hence abortion is wrong.
Pro-choice: No-one has the right to tell someone else what to do with their body. It is a pregnant woman's choice.
Several interesting issues are raised by this argument. One is at what stage does a cluster of matter become a human being, another is that the pro-choice movement do not even try to address this argument - insisting instead that the rights of the mother are paramount over an egg, zygote, embryo or fetus.
First let us examine the question of where human life begins. Does this begin at contraception (the banning of condoms by the Catholic church suggests they believe this) at conception, at the first cell splitting, at the point where the heart starts beating, at the point where the child is capable of survival outside the womb, or at the chosen time of birth?
Weird religious arguments aside, most people agree that human life is more important that the lives of animals. Yet they are not distinguishable (except through DNA testing) at the early stages. The characteristics which make us human are not expressed, but are still regarded as valuable to most people. It is a recognition of potential.
Curiously, is that is usually the pro-choice activists who do believe in forcing people to help others. The feminist movement, so popular in the 1980s and 1990s pushed very hard for single mothers to be given both government assistance and child welfare money from the fathers of those children.
The feminist view seems to be that women have no obligation to carry a fetus even for its survival, but the taxpayer has an obligation to pay for the raising of her children (if she chose to have them), and the father of the children had an obligation to pay for them even if he was not permitted to carry out the usual roles of a father.
A thought experiment may provide focus:
Some would say that no-one has obligation to another. Others say you have an obligation to carry the machine and let the person die.
If your answer is that you have the right to let the person die, then surely you have no obligation to pay taxes for someone else's welfare.
See