That's not a tenet of solipsism and it doesn't follow from anything. — Terrapin Station

It follows from assuming from assuming that everything that there is to know is contained within the world. And, if the solipsist self is one and the same with the world, then s/he knows everything there is to know about the world.

Maybe it may be easier to assume that God is a solipsist, also?

You completely ignored this part: "Consider thoughts you have, things you imagine, ways you feel, etc. Aren't they sometimes vague/uncertain for you?"

You completely ignored this part: "Consider thoughts you have, things you imagine, ways you feel, etc. Aren't they sometimes vague/uncertain for you?" — Terrapin Station

Well, yes, there's the issue of hidden processes of the mind that are unknown to the conscious mind, such as intentions, the very existence of dream characters (a really interesting question, as to how do dream persona have their own intent), and feelings.

But, this seems to not detract from the gist of the solipsist being tantamount to a fictional god-like entity. I mean, aren't you in control of all aspects of your dream-world, when you dream?

Well, yes, there's the issue of hidden processes of the mind that are unknown to the conscious mind, — Wallows

I'm not talking about things that are hidden or unknown/not conscious.

Are you telling me that all of your conscious thoughts, imaginings, feelings, etc. are certain for you and never vague, fuzzy, etc.?

I'm not talking about things that are hidden or unknown/not conscious. — Terrapin Station

Then please specify, what's the problem in my analysis of claiming that a solipsist (such as a God) is epistemically omniscient?

A solipsist cannot doubt because they are trapped in their own world. Epistemically closed off, hermetically sealed, thus doubt cannot arise because it is the opposite of what a solipsist experiences, supreme certainty — Wallows

Solipsism (/ˈsɒlɪpsɪzəm/ (listen); from Latin solus, meaning 'alone', and ipse, meaning 'self')[1] is the philosophical idea that only one's mind is sure to exist. As an epistemological position, solipsism holds that knowledge of anything outside one's own mind is unsure; the external world and other minds cannot be known and might not exist outside the mind. As a metaphysical position, solipsism goes further to the conclusion that the world and other minds do not exist. This extreme position is claimed to be irrefutable, as the solipsist believes themselves to be the only true authority, all others being creations of their own mind. — Wikipedia

As you can see the solipsist view stems from doubt that the question "do other minds exist?" clearly demonstrates. I don't see how that questioning mind, the doubt that bothers the solipsist, leads to certainty as you put it.

As you can see the solipsist view stems from doubt[/] that the question "do other minds exist?" clearly demonstrates. I don't see how that questioning mind, the doubt that bothers the solipsist, leads to certainty as you put it. — TheMadFool

Imagine if you were a true solipsist, or "God", does God doubt? Wouldn't an omniscient being not even be able to doubt?

Imagine if you were a true solipsist, or "God", does God doubt? Wouldn't an omniscient being not even be able to doubt? — Wallows

How's omniscience related to solipsism?

From what I can see solipsism is born from not knowing rather than knowing. You may be referring to hardline solipsism here but I don't subscribe to the belief that only I exist.

How's omniscience related to solipsism? — TheMadFool

Yeah, well think about it this way. I am omniscient, there is nothing more to know about the "world". Hence, the life of a solipsist is epistemically absolute, no doubt can arise.

From what I can see solipsism is born from not knowing rather than knowing. You may be referring to hardline solipsism here but I don't subscribe to the belief that only I exist. — TheMadFool

Pretty much hardline solipsism.

Yeah, well think about it this way. I am omniscient, there is nothing more to know about the "world". Hence, the life of a solipsist is epistemically absolute, no doubt can arise. — Wallows

But it's not necessary for there to be no other minds. An omniscient being may come to know other minds exist.

But it's not necessary for there to be no other minds. An omniscient being may come to know other minds exist. — TheMadFool

That may be true, but doesn't detract from God ever truthfully answering a question with:

I don't know. — Said no God ever.

1) It is possible for an omniscient being to know other minds exist. So omniscience doesn't lead to solipsism.

2) Solipsism arises from doubt and so solipsism doesn't entail certainty.

As for an external reality let's try proving that proving whether it exists or not is impossible or possible. I'll try proving that it's impossible for us to know anything about the existence or nonexistence of an external reality.

Our senses can be likened to TV screens through which we perceive reality and we're like people trapped in our TV rooms with no doors or windows. Our only access to the world is the TV. How can we ever know that the TV is giving the right information or not? So, it seems that solipsism actually refutes your claim and although it's impossible to deny an external reality we can "certainly" put such a notion in doubt.

1) It is possible for an omniscient being to know other minds exist. So omniscience doesn't lead to solipsism. — TheMadFool

Not really. Think about a dream world which you inhabit during sleep. You see other people in it who seemingly have an intent of their own. But, the reality of the solipsistic dream world is one where you are the only mind present in it, and your-self is the only mind creating these dream characters with "other minds". Hope that makes sense. It's important that I highlight here that the solipsist's self is one and the same with the "world". There is nothing beyond this solipsistic world, epistemologically.