Now you're just being stubborn. I say things that are untrue all the time. I don't know that they are untrue, but they are untrue nonetheless. That doesn't make them lies. I am not intending to be misleading. I'm just not smart enough to know the truth of some (many/all) things.

A lie is an intent to mislead. It is not an untruth. It does not even need to be false. I don't even need to do anything at all to lie.

I can lie by omission. I can lie by truth leaving out important context (still completely true though) and I can lie by telling an untruth.

In each case I must be willfully and intentionally misleading in order to be lying.

Your "perjury" example a lie by untruth. I can however, in a court of law, lie by omission (sometimes) or by context (often) without penalty. Perjury is defined as follows:

perjury: The crime of willfully and knowingly making a false statement about a material fact while under oath.

Notice the explicit statement of "willfully and knowingly" aka intent.

You must intend to mislead in order to lie. You cannot lie if you do not intend to mislead.

Its very simple. Intent is required and explicitly stated within every legal definition of the term, and every court case judgement that decides it. Intent must be proven beyond a reasonable doubt for a guilty verdict (in a criminal case). The act of telling an untruth is irrelevant.

Now you're just being stubborn. I say things that are untrue all the time. I don't know that they are untrue, but they are untrue nonetheless. That doesn't make them lies. I am not intending to be misleading. I'm just not smart enough to know the truth of some (many/all) things.

A lie is an intent to mislead. It is not an untruth. It does not even need to be false. I don't even need to do anything at all to lie.

I can lie by omission. I can lie by truth leaving out important context (still completely true though) and I can lie by telling an untruth.

In each case I must be willfully and intentionally misleading in order to be lying.

Your "perjury" example is only one of those, and doesn't even cover the entire gambit of possible lies.

perjury: The crime of willfully and knowingly making a false statement about a material fact while under oath.

Notice the explicit statement of "willfully and knowingly" aka intent.

You must intend to mislead in order to lie. You cannot lie if you do not intend to mislead.

Its very simple. Intent is required and explicitly stated within every legal definition of the term, and every court case judgement that decides it. Intent must be proven beyond a reasonable doubt for a guilty verdict (in a criminal case). The act of telling an untruth is irrelevant.