There was a novelization released at the same time as the movie. The official author was George Lucas, though I’ve heard it was actually penned by Alan Dean Foster. It included 16 pages of color photos from the movie, which was pretty wild for the time. It did mention Senator/Emperor Palpatine in the first chapter. And Han shot first.
I remember seeing that on the paperback rack of a department store, must have been just a few weeks before the film came out. I had no foreknowledge of the film’s release, and read the back cover to decide whether I wanted to buy it.
Even to my 15-year-old self it sounded contrived and derivative. I passed.
Yes, the novelisation of the first movie. But from Empire Strikes Back through to the resurgence of the Expanded Universe in the early 90s, even though it was pretty clearly spelled out in that prologue, nobody seemed to officially refer to the Emperor as Palpatine at any point. The first time it was starting to be adopted was, I think, when Cam Kennedy was drawing the Dark Empire comics for the story about the Emperor cloning himself.
Did George change the novel, too? 
Hm - better move my copy to a safe deposit box.
Most people think of sorcery as being a different type of magic. Yoda comes across more like a psychic martial arts master than a sorcerer. He’s not brewing potions or casting spells, but training a kid how to fight. He’s more mystical than magical.
Not that I think that’s too relevant to people who thought that the Emperor was a sorcerer. Just pointing out why it seems odd to me to give Yoda such a title.
General Motti: Don’t try to frighten us with your sorcerer’s ways, Lord Vader. Your sad devotion to that ancient religion hasn’t helped you conjure up the stolen data tapes or given you clairvoyance enough to find the rebels’ hidden fortre–<choking noises>
Darth Vader: I find your lack of faith disturbing.
The way I see it, the key difference between magic and psychic powers is that magic is external, while psychic powers are internal. Magic comes from some outside source - demons, other dimensions, mana, what have you - while psychic powers come from the user’s own mind. In Ep. IV, Obi-Wan clearly describes the Force as something that “surrounds all living beings”; in other words, an external force. That makes it magic.
To get back to the OP – we thought the Emperor was the frakkin’ Emperor! He was Darth Vader’s more eeeevil boss, and I also do not understand why there would be any reason to differentiate between a wizard, a sorcerer, or a Force User within the framework of the movies.
YES!
The novelization of ROTJ at the time referred to the Emperor as Palpatine. It also had some dialogue that indicated Palpatine knew Yoda and had sussed out from Luke that Yoda had given Luke some training.
Vader and Palpatine are both looking to recruit Luke. Vader, being “more machine than man”, cannot defeat Palpatine alone. Palpatine knows that a still 90% “human” Luke would be a far more powerful apprentice going forward than lava-roasted/walking iron lung Vader. They both know exactly the other one is up to… that’s just how the Sith roll.
By the transitive property, father and son could team up with the Emperor without breaking the Rule Of Two if Luke would just lose some more body parts.
The ROTJ novelization also contains the Cliff’s Notes version of his backstory - he was a Senator from a backwater planet, then “President of the Republic”, then declared himself Emperor at the end of the Clone Wars.
The Emperor was done with Vader. His goal all along was to turn Luke and have Luke replace Vader as his apprentice.
Vader was, in theory, looking to turn Luke and offered to have them both over throw teh Emperor but I think you can make a case that that was a lie Vader told to try and seduce Luke and he was always loyal to Palpatine until the end of Jedi.
The whole “only ever two” thing makes a lot more sense when you realize that it only applies to the Sith, who are just a sub-type of “Dark Force Users.” The Sith didn’t invent the Dark Side, and they’re not gatekeepers who determine who is and is not going to turn to the Dark Side. Anyone who is strong in the Force who allows himself to be overcome by anger, despair, or greed can turn to the Dark Side. The Sith are a specific cult of Dark Force users. Their strict one master/one apprentice set up is unique to their order.
It’s important also to remember that the Sith are a cult. They’re not acting out of rational self-interest, but in pursuit of a religious ideology that places strength as the ultimate (if not sole) virtue. A lot of people ask why a Sith would get an apprentice when they know for a fact that their apprentice will eventually try to kill them. I think, however, that to a Sith, that’s the entire point of having an apprentice. The Sith believe that only the strongest can be master of their order. A Sith master, therefore, is always training his own assassin, because if he can train someone to be strong enough to kill him, then he has advanced the cause of the Sith order itself by ensuring that it’s leader is the strongest person possible.
Vader’s offer to Luke was, I think, mostly legit - however, it was preconditioned on Luke turning to the Dark Side. The entire duel between Vader and Luke is a psychodrama designed to push Luke over the edge and get him to embrace the Dark Side, with both Vader and the Emperor trying to maneuver Luke so he’s pointing at the other guy when he finally goes off. Vader stopped Luke from striking down the Emperor at the beginning, because Luke wasn’t close enough to the edge then. Killing the Emperor at that point wouldn’t have turned Luke - rather, it would have resolved a lot of the tensions in Luke that were pushing him to the Dark Side in the first place.
When ROTJ came out, we had just seen two whole movies which bludgeoned us with the light side/dark side business. It never occurred to me to think of Palpatine as anything other than a dark side Force user.
Actually, the Rule of Two didn’t come out until the movie. Before that, there were multiple Siths. And even after the ROT was established, it was often violated, as well as there were other Sith practicioners out there. (The Lost Tribe of the Sith)
I guess I didn’t pay close enough attention to the prequels… I assumed there could be more than one Sith, but each Sith Lord had one apprentice. I guess for some reason I assumed at one time that Dooku/Darth Tyranus was Palpatine/Darth Sideous’ apprentice. But it sounds more like he is simply a dark Jedi rather than a Sith, but then what is the difference between a dark Jedi and a Sith apprentice?
ETA: I know Yoda said in TPM something like “Always two, no more, no less, a master and an apprentice” but I read that mean that if you’re dealing with a Sith, be aware that there is another involved in some way…
He shot lightning out of his fingers, had the very powerful force user Vader bowing and calling him Master, and right before trying to kill Luke, told him “Your feeble skills are no match for the power of the Dark Side.” I don’t think you get much more explicit than that. Did I mention he shot lightning out of his fingers?
I’m curious as to where you read this, 'cause it sounds like a pretty weak argument.