Is morphology how words are built up or how they are broken down? Which argument is more accurate? How does that support how words are stored in our mental lexicons?
Both definitions work, and in fact, they compliment one another. Morphology (in linguistics, not biology) studies ways in which languages form words from parts, and so a linguist studying morphology would consider things like roots, suffixes, prefixes, etc. and how those are put together to make a unit of meaning out of a word. In fact, the morphological study of a word will involve "breaking it down" in order to understand how the parts work together as a whole. We can break down the word itself as an example. The root "morph-" denotes "form" or "shape." The suffix "-ology" means "the study of" or "a record of." Putting those two together, we get "the study of form or shape." I mentioned biological morphology, which studies, guess what: body forms among living things and how they interact. We can also pluralize the word, and speak of morphologies: the shift from the -y to the -ies indicates the change from one to more than one. Pluralizing or changing tense with word endings are also morphological.
In terms of how morphology relates to "our mental lexicons," languages all follow surprisingly similar rules, because our brains have developed the instinctual ability, through millennia of evolution, to learn the particulars of a language's patterns within the first several years of life. One of these is the way in which the language uses arrangements of word parts to create and shape meaning when using the words. In fact, a particular section of our brain focuses on these (and other) linguistic patterns. That part of the brain, in conjunction with our memories, helps us understand what someone means when, for instance, they use a word that may be changed based context. Consider two examples: verb tense and contextual understandings. We use verb tenses to understand the difference between "stand" and "stood," as the difference between past and present. We also are sometimes able to fit together context and word parts we're familiar with to understand the meaning of a word we've never experienced. If we'd never heard of "biology," we may be able to put it together: "bio-" relates to life, and "-ology" means a record or a study of something, and since the sentence says "biology class" it probably means "the study of life."
check Approved by eNotes Editorial