Newaccount456 has already covered your confusion over the difference between a movement of and a shift along the supply curve adequately. That entirely covers the more than one equilibrium point because even in Econ 101 they tell you the curves shift. Of course there are multiple equilibria. Increasing, decreasing and constant economies of scale will be in every intro textbook.
Re: Price taking or perfect competition, that’s just one of the basic models of price determination. Monopoly, monopsony, oligopoly and monopolistic competition are all treated in introductory courses too and if you got as far as an intermediate course they’d cover the Bertrand, Cournot and Stackleberg models of oligopolistic competition and how they contrast with perfect competition and monopoly. Even introductory microeconomics will cover the three basic methods of price determination verbally.
Your penultimate paragraph also relies on not being able to distinguish between a movement of a demand curve and a shift along an existing one.
> Newaccount456 has already covered your confusion over the difference between a movement of and a shift along the supply curve adequately.
I think you're wrong, nobody is confused about shift of the curves. The problem really is, there can be multiple equilibriums even if the curves stay the same.
It is kind of difficult to see and understand why, because the traditional supply/demand theory and diagrams obscure this heavily. But if you look at the problem differently (see my other reference to Blatt), and start taking into account several products at the same time, you will see why.
This is exactly it. The single equilibrium hinges on the assumption about the monotonicity and slopes of supply and demand. But these assumptions are simply wrong, and so multiple equilibria are possible even with a single market. Multiple markets of course make the problem worse.
Re: Price taking or perfect competition, that’s just one of the basic models of price determination. Monopoly, monopsony, oligopoly and monopolistic competition are all treated in introductory courses too and if you got as far as an intermediate course they’d cover the Bertrand, Cournot and Stackleberg models of oligopolistic competition and how they contrast with perfect competition and monopoly. Even introductory microeconomics will cover the three basic methods of price determination verbally.
Your penultimate paragraph also relies on not being able to distinguish between a movement of a demand curve and a shift along an existing one.
Everything you wrote is covered in intro micro.