Its a good rule of thumb but should not be used as an explanation or argument. Its not an argument.
Sometimes people I respect claim that sex is wrong if both parties are not consenting with understanding, and I object that its not an argument. I can probably agree with that rule of thumb, but it isn't an argument. I also hear some say just that Consent is required. That's not a terrible rule of thumb either. The strengths of these are that they protect children animals and people who can't think clearly, but these claims lack the performative reason why. They don't discuss the human being or connect to our basic physiology and psychology. If we are arguing about ethics then it seems like they are an evasion of the subject. As a rule of thumb 'Consent with understanding' is workable, but it is not a reason and not an argument. I'll give an example of actual arguments which support the rule of thumb:
Here is an actual argument for why sex with children is wrong: Children have the gift of seeing life without the added confusion that sex imposes upon adults. Children also lack a strong sense of self. When the adult's aggression (through sex) is unleashed upon children, that adult undermines and betrays the gift children have and can also damage their personalities. Rather than caring for the children, the adult becomes a user of children.
Here is one for why sex with animals could be wrong: People and animals have germs, and sometimes those germs cross over during sex which leads to STD's.
Here is one real argument for why sex with people who don't understand is wrong: They are not your property. This depends of course upon understanding why people should not be property (chattel), but it is an argument.
Sometimes people I respect claim that sex is wrong if both parties are not consenting with understanding, and I object that its not an argument. I can probably agree with that rule of thumb, but it isn't an argument. I also hear some say just that Consent is required. That's not a terrible rule of thumb either. The strengths of these are that they protect children animals and people who can't think clearly, but these claims lack the performative reason why. They don't discuss the human being or connect to our basic physiology and psychology. If we are arguing about ethics then it seems like they are an evasion of the subject. As a rule of thumb 'Consent with understanding' is workable, but it is not a reason and not an argument. I'll give an example of actual arguments which support the rule of thumb:
Here is an actual argument for why sex with children is wrong: Children have the gift of seeing life without the added confusion that sex imposes upon adults. Children also lack a strong sense of self. When the adult's aggression (through sex) is unleashed upon children, that adult undermines and betrays the gift children have and can also damage their personalities. Rather than caring for the children, the adult becomes a user of children.
Here is one for why sex with animals could be wrong: People and animals have germs, and sometimes those germs cross over during sex which leads to STD's.
Here is one real argument for why sex with people who don't understand is wrong: They are not your property. This depends of course upon understanding why people should not be property (chattel), but it is an argument.