Intro, Part One, Part Two, Part Three
Circular arguments are somewhat similar to assuming the position you need to prove but slightly different. When pro-choicers use this tactic they argue in a circle instead of providing an actual reason for their beliefs. Instead of simplying asserting a belief that they need to prove, they respond to questions with other assertions that simply assume the previous assertion instead of providing reasoning.
Joe Choice: "The unborn may be humans in the biological sense but they're not persons?"
Joe Life: "What's the difference between humans in the biological sense and persons?"
Pro-choice answers to this question will vary. Some will say being born makes a human being into a person, others will say the lack viability (the unborn's inability to breathe by themselves) makes them non-persons, others will say some kind of brain function such as self-awareness, consciousness, etc. makes human beings into persons.
Joe Life might then ask, "Why should anyone accept your criteria for what a person is over anyone else's criteria say the criteria of someone who says that blacks aren't persons because of their skin color or the criteria of someone who says that women aren't persons because of their gender?"
Joe Choice will probably then say something like, "Because born humans are persons" or "because all persons have a certain level of mental functioning."
But this is a circular argument. Pro-choicers say the "unborn aren't persons because of their lack of mental functioning." Why does mental functioning matter? "Because persons have a certain level of mental functioning." They are using their premise to prove their conclusion and then using their conclusion to prove their premise.
This is no different from someone saying, "Women aren't persons because only males are persons."
Or someone saying that "African-American aren't persons." Why? "Because only humans with light skin are persons."
Example 2: "Fetuses are only potential persons/humans beings?"
Then what are they actually? If the unborn are a potential something they must also be an actual something as well because to exist and be a potential something means they exist and therefore must also be an actual something. So prolifers will ask, "What kind of being are the unborn actually?" Some pro-choicers will then say something like "Human fetuses."
This is no different from someone claiming that human infants are only potential persons/human beings. Then what are they actually? Human infants. This argument is completely circular.
People that argue in a circle never provide a principle reason to why we should accept their positions. Why? Because they don't have one.
On to Part Five