Recall Noonan's Argument:
| Noonan's Argument: | |
| | 1 | If x is an act of harming a human being and x has no sufficient reason, then x is morally wrong. | |
| | 2 | If x is an abortion then x is an act of harming a human conceptus (embryo, fetus). | |
| | 3 | A human conceptus is a human being. | |
| Therefore | 4 | If x is an abortion then x is an act of harming a human being. | 2&3 |
| | 5 | If x is an abortion then, if x is not a case of cancerous uterous or ectopic pregnancy, then x has no sufficient reason. | |
| Therefore | 6 | If x is an abortion and x is not a case of cancerous uterous or ectopic pregnancy, then x is an act of harming a human being and x has no sufficient reason. | 4&5 |
| Therefore | 7 | If x is an abortion and x is not a case of cancerous uterous or ectopic pregnancy, then x is morally wrong. | 1&6 |
| Thomson's Variation: | |
| Step 1: | 1 | Every fetus is a person. | |
| | 2 | Every person has a right to life. | |
| Therefore | 3 | Every fetus has a right to life. | 1&2 |
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| Step 2: | 4 | A fetus' right to life is more stringent than a mother's right to determine what happens in and to her body. | |
| | 5 | If a fetus' right to life is more stringent than a mother's right to determine what happens in and to her body, then no fetus may be killed. | |
| Therefore | 6 | No fetus may be killed | 4&5 |
Compare the two:
| 1 | Noonan's Argument is valid, as is Thomson's Variation. |
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| 2 | Both arguments take two steps. |
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| 3 | Both arguments assume that the human conceptus is a human being. |
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| | | - Premise (3) in Noonan's Argument
- Premise (1) in Thomson's Variation
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| 4 | Premise (4) in Thomson's Variation is an analog of Premise (5) in Noonan's Argument. |
