Old summary of issues
Main article NameTheTrait
For reference, Part 1 of NTT is as follows
- P1 - Humans are of moral value
- P2 - There is no trait absent in animals which if absent in humans would cause us to deem ourselves valueless.
- C - Therefore without establishing the absence of such a trait in animals, we contradict ourselves by deeming animals valueless
The primary issues that are established with the argument can be summarised as follows:
- P2 requires a trait that can be absent in humans
- Traits that can be absent in humans are all traits except 'being human' and 'moral value' (moral value because of P1)
- Traits that could give moral value to animals based on P1 are 'being human' or 'moral value'
- Neither of these traits can satisfy P2 as they cannot be absent in humans
- Therefore P2 does not assign the traits 'moral value' or 'being human' to animals
- Hence C 'Animals have moral' does not follow from the premises and the argument is a non sequitur
- If 'us/ourselves' in P2 refers to humans, then P2 becomes irrelevant since P1 says humans can never be valueless
- Even if NTT did establish that there is no moral value giving trait absent in all animals that would only imply there is at least one animal with the moral value giving trait, not that all animals have the moral value giving trait (which is the conclusion)
Isaac's response to these criticisms can be seen in the image to the right.
Regarding the defense, paraphrasing, ' P1 - Humans are of moral value, is a general statement ', general statements do not work in formal arguments. The statements '(1) humans are of moral value ' and '(2) some human(s) are of moral value' may seem very similar. But in formal logic, they are very different, and the difference dramatically changes what can be derived from them. With definitions used in the section below, the first statement would be expressed as
- (1) '∀x: H(x) ⇒ M(x) ' (for all x, if x is human then x has moral value)
and the second
- (2) '∃x: H(x) ∧ M(x)' (there exists an x that is human and has moral value)
This is why it's important to recognise the value of formal logic, and the necessity that we must prove the validity of our arguments with formal logic. Rigour is very important in philosophy, an argument shouldn't be able to be 'nitpicked', and formal logic is how we establish that our arguments are logically valid.
