At a minimum: Inform the moderators of the subreddit(s) you are planning to use and get consent.
Ideally: Ask the members of the subreddit for permission. Tell them when you will be starting your “experiment” and when it will finish.
What’s the hypothesis you are testing? What’s the benefit for them taking part?
- High chance of being outright rejected.
- potentially makes responses to your AI responses less natural
If you're genuinely interested in answering those (likely rhetorical) questions. Check out work on the ethical dimensions of deception and covert research, especially relating to online research. e.g.: https://ec.europa.eu/info/funding-tenders/opportunities/docs...
If you're interested in the consequences of research online that violates consent, here's a good primer, focusing on Facebook's emotional contagion research amongst others - https://journals.sagepub.com/doi/full/10.1177/17470161166806...
So then you do understand why he should be ethical: being an unethical person is a bad thing.
> why should he take it in the absence of laws that force him to or professional/reputational damage to him.
If the only reason that you behave ethically is because you will suffer consequences if you don't, then you are not ethical. I'd hope that such a person would have problems looking themselves in the mirror, but I know better.
This explains pretty much everything.
For this private kind of fun science, there is no need for ethics, unless one commits a crime or fears loss of personal reputation.
There is little consensus on a broad range of ethics.