Biberauer, Theresa2021-07-092021-07-092019Biberauer, T. (2019). Factors 2 and 3: Towards a principled approach. Catalan Journal of Linguistics, 2019(269752), 45�88. https://doi.org/10.5565/REV/CATJL.2192014-9719https://doi.org/10.5565/rev/catjl.219https://hdl.handle.net/10566/6387This paper seeks to make progress in our understanding of the non-UG components of Chomsky�s (2005) Three Factors model. In relation to the input (Factor 2), I argue for the need to formu-late a suitably precise hypothesis about which aspects of the input will qualify as �intake� and, hence, serve as the basis for grammar construction. In relation to Factor 3, I highlight a specific cognitive bias that appears well motivated outside of language, while also having wide-ranging consequences for our understanding of how I-language grammars are constructed, and why they should have the crosslinguistically comparable form that generativists have always argued human languages have. This is Maximise Minimal Means (MMM). I demonstrate how its incorporation into our model of grammar acquisition facilitates understanding of diverse facts about natural language typology, acquisition, both in �stable� and �unstable� contexts, and also the ways in which linguistic systems may change over time.enThree factorsUniversal grammarAcquisitionCrosslinguistic variationPoverty of the stimulusArticle