The English language is a collection of words with attached meanings. A concrete noun, in particular, means a thing or a collection of things. Sometimes two such nouns refer to overlapping categories, other times to non-overlapping categories. For instance, the words ‘horse’ and ‘cow’ refer to two categories, and nothing lies in both categories.
This thread is about two other such nouns that don’t overlap: ‘fetus’ and ‘person’.
A fetus is the thing existing during pregnancy within a woman’s body. A person is the thing that comes into existence after birth, after the pregnancy ends.
No one tries to warp the definition of fetus. Those who wish to convince us that a fetus can be person will focus and changing the definition of person. But the definition of a person is clear: a person has a physically independant body and a mentally independant mind. Hence during a pregnancy there can’t be a second person existing as a part of a woman’s body. The person only starts existing at the moment of birth.
And how shall we know that this definition is correct? By logic, common sense, legal agreement, moral agreement, and religious agreement.
When we walk into a room, we can tell how many people are in the room. It’s rather easy, we just count up the number of bodies we see. The idea that there may be extra people hiding inside some of those bodies never crosses our mind, not even the minds of those claiming to believe that a fetus is a person.
Obviously there is a stage early in pregnancy when an observer cannot even tell that the woman is pregnant. If life began at conception, we would then have a case of a human being who existence provided no evidence whatsoever to the outside world. This is abusrd.
Legally a fetus is not a person. It has no rights, doesn’t count as a person on a census, and can’t be taken into custody if a court determines that it’s being abused (as even a baby can).
Religiously, many religions claim to view a fetus as a person. Realistically, though, none of them actually treat a fetus that way.
On logical grounds, consider this. A week from now is my twenty-third birthday. What does that mean? It means that, on that day, I will be twenty-three years old. Alternately, it will have been twenty-three years since my birth. Alternately, I will have been in existence for exactly twenty-three years. If I had actually been a person at the time of conception, then my twenty-third birthday would instead have fallen at the start of last December.
Suppose an elevator has a limit of five people. Can three pregnant women ride it simultaneously? Obviously they can.
etc…
The bottom line is this. Some people say that a fetus is a person. Others say it’s not. But those who claim to believe that it is do not act in a way that agrees logically with that belief.