(also known as: moral fallacy)
Description: The assumption that what ought to be is what is -- that the undesirable opposes nature.
This is the opposite of the naturalistic fallacy.
Logical Form:
X ought to be wrong.
Therefore, X is wrong.
Example #1:
Adultery, as well as philandering, is wrong.
Therefore, we have no biological tendency for multiple sex partners.
Explanation: While, morally speaking, adultery and philandering may be wrong, this has no bearing on the biological aspect of the desire or need. In other words, what we shouldn’t do (according to moral norms), is not necessarily the same as what we are biologically influenced to do.
Example #2:
Being mean to others is wrong.
Therefore, it cannot possibly be part of our nature.
Explanation: While, morally speaking, being mean to others may be wrong, this has no bearing on the biological aspect of the desire or need. Again, what we shouldn’t do (according to moral norms), is not necessarily the same as what we are biologically influenced to do.
Exception: An argument can certainly be made that an ought is the same as an is, but it just cannot be assumed.
