What if you cannot confirm a fact? Is it a fact then? For example, the pirahá have concept of numbers. They have the words one, two, and many. Researchers for years have been trying to teach them to count but the strange nature of their language just doesn't allow it(they are not retarded, they just speak a very restrictive language that alters the way your brain thinks) so if you show them 5 balls in your hand, and state that you have 5 balls, is it a fact? To them you just have more than "one" ball. 5, 8, 12, 67, it's all irrelevant.

A lie can be a false opinion or a false fact.

Fact Example: The holocaust didn't happen.

Opinion Example: Gandhi and Mother Teresa were assholes.

As long as it's not true, it's a lie.

a fact is defined as something that is true, something that actually exists, or something that can be verified according to an established standard of evaluation.

http://en.wikipedia.org/wiki/Fact

An opinion is a person's ideas and thoughts towards something. It is an assessment, judgment or evaluation of something. An opinion is not a fact, because opinions are either not falsifiable, or the opinion has not been proven or verified. If it later becomes proven or verified, it is no longer an opinion, but a fact.

http://en.wikipedia.org/wiki/Opinion

I assume that a lie falls into the opinion category.

i guess that it could depend on whether you know the lie to be untrue or not. to use your example, if you say the sky is blue, believing it to be true, i guess that it is merely a false fact, but if you are trying to fool someone (i.e. knowing the sun isn't blue but trying to make someone believe that it is) then it could be seen as more of an opinion because your trying to subjectively say that the blueness of the sun outweighs its yellowness or whatever color. or maybe its all in how you word it (as someone pointed out), either way good topic/question...

blanko can we please leave out suggestions which add other facts not mentioned? look at the sentence without any other information and then decide what it is.

back to the topic at hand:

a lie is simply the intention of misdirecting your attention from the truth. But there are rules involved:

to lie you need to know the truth, since lies are opposites of truth

bullshit on the other hand considers neither truth or lie, just a way to get by. It ignores the rules of the game completely.

read "on bullshit" by frank herbert, its like a 15 min read. really tiny book

God doesn't exist.
God exists.

Both are facts, regardless of whether they are true or not.

It's a 'False fact' if you would like, No such thing exists to my knowledge, But that is the way i would describe it.

Why a lie is a lie has to do with iuntent, and a lie may relate to fact or opinion.

A cop may say did you do this, and you say no when in fact you did. That is a lie regarding a fact.

If you want to suck up to your boss, who is a Bushite, you may state an opinion favorable to Bush to curry favor, when in truth you despise the vapid war criminal, thus making a stated opinion a lie.