[BoxKeyboard]

Because you don't really know what the longterm effect on the subjects is going to be, especially w.r.t behavioral studies. The human psyche is still in many ways very much a black box, and there are plenty of questionable behavioral studies where the consequences of the study greatly outweighed the benefits.

As far as deliberate vs. random goes, it's an important distinction because intent and consent are arguably paramount when dealing with questions of morality and ethics - as reflected by our legal system, where intent and consent are often a source of debate. In this case, experimentation is clearly done with intent and often without explicit consent (as opposed to the implied consent given by the Terms of Use).

It's why giving someone HIV (or Syphillis) unknowingly isn't illegal or really all that immoral (because the infector is unaware), but it is illegal to infect people intentionally.

[yummyfajitas]

You don't know the long term effects of random social media posts either. Before doing some sort of a controlled study you can't know.

Recently I went to a conference and acted like a sales guy. I gave different (truthful) pitches to different people and observed how enthusiastic they seemed about the product afterwards. Was that also unethical? Would it become unethical if I did a hypothesis test afterwards, rather than merely going with my gut?

[BoxKeyboard]

> You don't know the long term effects of random social media posts either.

Right, hence the whole rest of my message concerning intent, consent, and their importance with regards to morality and ethics.

> Was that also unethical?

Maybe? I wasn't there, I can't tell you. There are plenty of ways to act VERY unethically when it comes to sales and advertising, even while being truthful (e.g. you could omit some very important information). Deceptive advertising is a whole class of illegal actions in many developed nations, and not all of those actions involve the strictest definition of lying.

Not sure what hypothesis testing has to do with anything, experimentation certainly doesn't need to go hand-in-hand with statistical analysis.

I almost added a bit about taking the whole thing to its logical conclusion that the entire field of advertising and sales is arguably unethical. I haven't really thought that entirely through so I omitted it, but it's food for thought nonetheless.