1. abortion
persons ii

2. the modified species criterion
The Modified Species Criterion: Something is a person iff it is a member of a species generally characterized by C
the modified species criterion

3. the modified species criterion
The major difficulty… is that it requires further explanation why C should determine moral personhood when applied to classes of creatures rather than to individual cases… Just because opposable thumbs are a characteristic of Homo sapiens, it does not follow that this or that particular Homo sapiens has opposable thumbs. There appears to be no reason for regarding right- possession any differently, in this regard, from thumb-possession. (F&L, p.205)
the modified species criterion

4. the potential possession criterion
The Potential Possession Criterion: Something is a person iff it either actually or potentially possess C.
the potential possession criterion

5. the potential possession criterion
It is a logical error, some have charged, to deduce actual rights from merely potential (but not yet actual) qualification for those rights. What follows from potential qualification, it is said, is potential, not actual, rights… “A potential president of the United States is not on that account Commander-and-Chief.” (F&L, p.206)
the potential possession criterion

6. the potential possession criterion
Potential possession of C confers not a right, but only a claim, to life, but that claim keeps growing stronger, requiring ever stronger reasons to override it, until that point when C is actually possessed, by which time it has become a full right to life. (F&L, p.207)
the potential possession criterion

7. the actual possession criterion
The Actual Possession Criterion: Something is a person iff it actually possesses C.
the actual possession criterion

8. summary The Species Criterion The Modified Species Criterion
The Actual Possession Criterion
The Strict Potentiality Criterion
summary