Logical fallacies

An "is" statement is a statement of fact, of reality, of what's happening right now. In conversations about morality we put the statements of "is" aside and concentrate on the statements of "ought" instead, because an "ought" statement addresses not what the current reality is, but what we should do, what is moral to do, what is a moral act.
When talking about morality, and being asked a question about  what we should do, or what is morally right or wrong to do, answering such a question with an "is" statement achieves 2 things:
1. Changing the subject: if we're making an "is" statement, we're no longer talking about morality.
2. Diffusion of responsibility: we're trying to appeal to societal norms to reach the conclusion that we shouldn't question the morality of an act because it's widely spread.

The the claim is that natural things are good or better than synthetic and unnatural things. This is not unilaterally correct, some natural things are good or better, other natural things are bad or worse than synthetic and unnatural things. Assuming that something natural is always better than synthetic or unnatural is a fallacy because of the following:

1. It doesn't account for all the natural things that are harmful and even deadly

2. It makes an assumption instead of seeking evidence. 

Post hoc ergo propter hoc is an informal fallacy that states "Since event Y followed event X, event Y must have been caused by event X." It is a fallacy in which an event is presumed to have been caused by a closely preceding event merely on the grounds of temporal succession. This type of reasoning is fallacious because mere temporal succession does not establish a causal connection.

The Nirvana fallacy is a logical fallacy in which one assumes that a perfect solution to a given problem exists, and rejects more realistic answers in favour of it.

It can also be applied disingenuously to stone wall solutions to problems that some do not think are problems.

The fallacy is an ad hoc moralistic fallacy and an informal fallacy.

A category error is a mistake that occurs when something is incorrectly ascribed to a category it does not belong to, such as treating a property of one category as if it applies to another. For example, saying "animals are food" is committing a category error. Animals are not food, they're exploited and killed to create food. "FOOD" belongs to the category of "object", "ANIMAL" belongs to the category of a sentient being.