Page "Equal consideration of interests" Paragraph 4

and in doing so, pointed out that the relevant characteristic for a right not to be forced to suffer ( physically or mentally ) is the ability to feel physical or mental anguish — rather than arbitrarily and illogically appealing to a species ' ( or a child's ) ability to reason or talk, which are irrelevant characteristics because they have nothing to do with physical / mental suffering.

Likewise, just because it is sensible not to bother with addressing a man's right to receive an abortion, does not mean that only women should be protected from torture.

Instead, Singer argues, a consideration of interests should be equal to that of a human ( or a man or an adult ) only whenever the two groups share similar relevant characteristics.