Origins
The English verb "assume" traces its origins to the Latin term "assūmere," which means "to take up," "to take to oneself," or "to adopt." This Latin verb is a compound formed from the prefix "ad-" meaning "to" or "toward," and the verb "sūmere," which means "to take" or "to obtain." The verb "sūmere" itself is a contraction of the earlier Latin phrase "sub-emere," literally "to take from below," where "emere" means "to buy" or "to take."
The root "emere" is etymologically significant, as it derives from the Proto-Indo-European root *h₁em-, which carries the general sense of "to take" or "to distribute." This PIE root is well-attested across various Indo-European languages, producing cognates such as Old Irish "ar-fo-emat," meaning "they accept," and Lithuanian "imti," meaning "to take." These cognates demonstrate the inherited nature of the root *h₁em- within the Indo-European family, distinguishing it from later borrowings.
The Latin "assūmere" thus originally conveyed the physical act of taking or acquiring something, often with a volitional or deliberate nuance, as in taking up a responsibility or adopting a role. This concrete sense of physical acquisition or assumption is preserved in Latin usage and is reflected in English borrowings from Latin, especially in legal and theological contexts.
Latin Roots
"Assume" entered the English language in the early 15th century, primarily through the influence of legal and theological Latin. Its earliest English uses retained the original sense of "taking upon oneself," particularly in contexts involving authority, office, or responsibility. For example, one might "assume" a position of power or "assume" duties, emphasizing the act of deliberate acceptance or adoption.
By the mid-16th century, the semantic range of "assume" expanded to include a more abstract, epistemic sense: "to suppose without proof" or "to take for granted." This development reflects a metaphorical extension from the physical act of taking up something tangible to the mental act of "taking up" a proposition or idea. In this sense, "assume" came to mean accepting a premise or supposition as true, without necessarily having evidence to confirm it.
The theological use of "assume" also preserves the original spatial metaphor of taking up or lifting. The term "the Assumption," referring to the bodily taking up of the Virgin Mary into heaven, shows this usage. Here, "assume" denotes a literal, physical elevation or taking up, consistent with the Latin root meaning.
Proto-Indo-European Roots
The semantic trajectory of "assume" is notable for its gradual abstraction. It begins with the concrete act of physical acquisition or purchase, as indicated by the root "emere" and its PIE antecedent *h₁em-. It then moves to the volitional adoption or acceptance of roles and responsibilities in Latin "assūmere." Finally, it culminates in the English epistemic sense of presupposition or supposition, where "assume" means to accept something mentally without proof.
This progression illustrates a common pattern in semantic change, where words with concrete, physical meanings develop more abstract, metaphorical senses over time. The case of "assume" is particularly well-documented, with clear etymological links and attested stages in Latin and English usage.
"assume" is an inherited Indo-European verb rooted in the PIE *h₁em-, passing through Latin "emere" and "assūmere," and entering English in the 15th century with a primary sense of taking upon oneself. Its later development into the sense of "to suppose without proof" reflects a metaphorical extension from physical taking to mental acceptance. The theological and legal uses of the word preserve the original spatial and volitional nuances, providing a rich etymological history that spans from concrete acquisition to abstract cognition.