Precise regulation of correct cell fate decisions is crucial in the development of multicellular organisms, during which cells differentiate from a single cell to the multitude of cell types that compose the adult organism. Incorrect cell fate decisions can lead to various diseases, such as cancer. Experimentally, cell-decision making has been well studied in the context of a single cell. However, how cells make decisions in their multi-cellular environment still remains elusive. Starting from the example of migration/proliferation plasticity, a cell decision-making mechanism found in tumour cells, I will introduce the current challenges of the problem. To address the latter, I proposed the Least Environmental Uncertainty Principle (LEUP) as a candidate theory to understand cell decisions. In particular, LEUP uses statistical physics tools that allows for (i) a low-dimensional description of relevant dynamics, and (ii) coupling between single-cell decisions and the corresponding collective behavior at the multicellular level. Finally, I will outline the main mathematical premises of the proposed theory and application to cell decision-making related to collective migration, tissue development and tumor growth.