Are there different definitions of indeterminacy?

General DSGE Modeling
1

Sometimes I encounter the word indeterminacy when macro books are discussing sunspot shocks, expectational errors, etc. (but stability and eigenvalues are not mentioned). Here, indeterminate equilibrium appears to be when you have sunspot shocks in the model.

Other times, I encounter indeterminacy when macro books are discussing stability, eigenvalues, BK condition, etc (But no mention of sunspot shocks, expectational errors). Here, indeterminate equilibrium appears to be when you have fewer unstable eigenvalues than jump variables in the model (i.e., the model is too stable leading to multiple equilibria)

And sometimes indeterminacy is mentioned when some equation does not converge.

Are these all kinda connected in one definition of indeterminacy? Thus,

  1. sunspot shocks and expectational errors
  2. stability and multiple equilibria.
  3. Divergence.

Thanks!

2

I haven’t encountered the last one. The first two are related. Whenever you have fewer unstable eigenvalues than jump variables, the model allows for multiple equilibria. That implies that expectational shocks (sunspot shocks) can be self-fulfilling. Essentially, sunspot shocks are the selector put in from outside of the structural model to select one of the multiple equilibria.