A lie is based on intent. If you're purposely intending to mislead someone, whether by omitting information or by outright stating false information, then it's a lie.

I'd say it's technically a lie: an intentional misleading. Paltering is its close cousin.

I wouldn't consider it in a vacuum. I also look at intent and consequences. Did they omit info to gain advantage over others, or were they refusing to tell a Nazi where they hid the jews? Did their choice lead to a better outcome for everyone, or did it cause chaos and disrupt lives needlessly?

Everyone going "duh it's still a lie" - calling someone a liar carries a specific connotation which I don't think applies in all cases of so-called "lies". To me, a lie carries with it not just an intentional falsehood but an accusation or an accusable misdeed. I wouldn't call someone a liar because they hid jews from nazis.

I think it depends on the context. If it's like a close friend and the deception screws you over and was an unexpected betrayal, then it's basically a lie. If there's some reason someone might suck at a job and they don't mention it in the interview and were not asked, that's different because it's an adversarial situation and looking out for yourself means not showing all your cards, and everyone should understand that it's like that.

Omission can be a lie as long as the intent is to deceive. Thats an important element to making something a lie

It really depends on context.

the crucial element of a lie is intention to decieve, either by ommission or commission

Depends. Intentionally omitting information in order to mislead? That's a lie. Simply not mentioning something? Or not mentioning it because it's embarrassing for you or someone else, because you didn't think it was relevant, or because it's not their business or not your business to share? Not really a lie. Not in the same way anyway.

If the person lying by omission has the intent of causing the recipient to have false understanding (e.g. to provide basis for a choice) then it's at least as dishonest as a blatant lie.

If they omit information because they think it's irrelevant then it's just ignorance or negligence. Dishonest in the sense that it's not forthright.

Neither lies nor omission are inherently unethical without some basis for the relation between the two people being honesty/loyalty.

Not sure I'd call it a lie according to these definitions...

A lie is an assertion that is believed to be false

a false statement made with deliberate intent to deceive; an intentional untruth

We don't need to call it a lie to ackowledge it still carries the same moral burden, judgement and implications.

I'd call it deception.

If Jean-Luc Picard says it’s so, it’s so.

Disagree

All lies are deceptions, but not all deceptions are lies

Lies are specific acts that are done, not acting is in itself not an act

Conservation of energy cannot be called an expenditure of energy

When people call something a "lie by omission" it's an attempt to shift the blame wholly to the other person rather than deal with the fact that part of the blame belongs to themselves

My silence was not a lie; you guessed about reality, and I just didn't correct you

You can still use it as a basis for future distrust and you can still use it as a reason to cut off or minimize future encounters

But it is not and should not be considered a malicious action against you as you would a lie

Disagree. It's deceptive, but not a lie. A lie is a deliberately false statement, which omission cannot be.

No. Otherwise everyone lies constantly by not telling everyone everything they are aware of at all times. Granted I met some people that would be pretty honesty by that metric. And everyone wants to get away from them.

The CIA recognizes it as a lie. So a lie.