How do I know? I don't, but it certainly looks that way. She so often tells blatant falsehoods with apparent sincerity, it is hard to think of any alternative explanation.
Clinton's latest lying lunacy occurred on Tuesday in Florida when she told the world that she was in New York on 9/11. She wasn't. She was, as a matter of public record, in Washington.
Why would any sane person make up such a ridiculous lie? How can she believe it benefits her? I do not know. But it is not the first of her ludicrous lies. Not by a long way.
The lies she told about her private server, whilst deplorable, at least made some kind of sense - she was trying to evade prosecution for her criminal behaviour. The lies she tells the electorate in this campaign about her policy positions (like open borders), at least make some kind of sense - she wants their votes. The lies she tells about the Clinton Foundation and pay to play at least make some kind of sense. The lies she told about Benghazi, whilst beyond reprehensible, at least made some kind of party political sense. But where is the sense in lying about being in New York on 9/11?
Then again she lied about being under sniper fire in Bosnia when in fact she had been offered some flowers by a little girl. What is the world to make of a woman who apparently cannot tell the difference between truth and lies? I don't know, but I don't think she should be in charge of... well, anything.