An LLM has a great deal of declarative knowledge. Eg. It knows that the first president of the US is George Washington. Like humans it has built up this knowledge through reinforcement, the more a fact is reinforced by external sources, the more you/ it knows it. Like with humans when it reaches the edge of its knowledge base it will guess. If I ask someone who the 4th president of the US was they may guess Monroe, that person isn’t lying, it’s just an area that hasn’t been reinforced (studied) as much so they are making their best guess, LLMs do the same. That doesn’t mean that person cannot and will not ever know the 4th president, it just means they need more reinforcement / training / studying.

Humans as well as LLMs have a declarative knowledge area with a lot of grey area between knowing and not knowing. It’d be like a spectrum starting on one end with stuff that has been reinforced many times by people with high authority, what is your name would probably be the furthest on one side, to another end with stuff you’ve never heard or heard from untrustworthy sources. LLMs may not have the other dimension of trustworthiness that people do but the humans training it will usually compensate that with more repetition from trustworthy sources, eg. They’ll put 10 copies of the new York times and only one of younewsnow.com or whatever in the training data.