When a polymer crystallizes from solution, it is well known that the resulting morphology depends on whether any liquid-liquid phase separation (LLPS),has preceded crystallization. In addition to the dense morphology that results when crystallization occurs directly from a homogeneous solution, at least three other distinctly different morphologies are produced if crystallization follows LLPS. Although much work has been reported in this regard, a framework that can relate the path that a process might follow across a phase diagram to the consequent morphology is lacking. We report here the fundamental elements of a simple thermodynamic framework that serves to identify the driving forces that produce these different morphologies. It is based on identification of the nucleating phase, if any, in LLPS and coupling it with the domain in which nucleation of crystallization occurs. The essential elements of the framework for morphological evolution are demonstrated by relating the sequence of phase transitions to the morphology which can result in the crystallized polymer when a polymer solution is cooled from a homogeneous state at a high temperature. Four distinctly different morphologies are shown to evolve, depending on whether crystallization occurs (a) directly from a homogeneous solution (dense); (b) following binodal liquid-liquid phase separation, LLPS, with nucleation of the polymer-rich phase (GMP-globular microporous); (c) following spinodal LLPS (FMP-fibrillar microporous); or (d) following binodal LLPS with nucleation of the solvent-rich phase (CTMP-cell-tunnel microporous). An important implication of the framework. is that a predictable sequence of "dense --> GMP --> FMP --> CTMP --> dense" morphologies has to arise with increase in overall polymer concentration in such solutions. The framework also serves to identify conditions, such as passage through specific temperature/concentration regions in the phase diagram, that would increase the likelihood of forming mixed or coexisting morphologies. However, it is still necessary to develop appropriate kinetic models to predict sizes of the morphological components within each of the four morphologies.