Why linguists are wary of telling people how to speak
Much of linguistics treats language as something to observe rather than police, and many linguists regard any prescriptivism as inconsistent with the objectivity they think an academic field should maintain [2]. That stance has a long background: even as the intellectual spirit of the nineteenth and twentieth centuries seemed to work against the very idea of prescriptivism, the notion persisted in American linguistics rather than disappearing [4].
The wariness is not purely philosophical. A mainstream view in linguistics holds that prescriptivism does not, and perhaps cannot, change how language actually develops [5]. If that is right, then prescribing rules is at best pointless and at worst misleading, which explains why the field has often treated the whole enterprise with suspicion.
Where prescriptive advice does earn its place
The case for a measured amount of prescriptivism rests on application rather than on theory. Oaks argues that the general stance against prescriptivism ignores the practical and appropriate use, as well as the potential use, of some prescriptive guidance across a range of applied linguistic disciplines [2]. In this view, the question is not whether prescriptivism belongs in linguistics at all, but how much of it belongs in the specific practical tasks where linguists' findings get used.
Editing and usage guidance are the clearest example. Prescriptivism serves an important purpose when editors and other language professionals apply findings from empirical linguistic studies to practical communication tasks [1]. That framing keeps the prescriptive advice tethered to evidence: the guidance is a downstream application of research, not a substitute for it.
How prescriptive are the usage guides people actually consult?
Smith measured this directly, coding entries for eight well-known usage problems, such as who/whom and lay/lie, across 11 current American English usage guides on a scale from 1 (minimally prescriptive) to 4 (maximally prescriptive) [1]. The results skewed high: six of the eight problems were treated as maximally prescriptive by at least two guides, and six had mean indexes at or above the scale's midpoint of 2.50 [1]. The guides themselves were similarly strict, with seven of the 11 giving maximally prescriptive advice for at least one problem and eight having mean indexes at or above 2.50 [1].
Yet the same study found a noteworthy amount of prescription-breaking advice, and concluded that usage guides vary considerably in their levels of prescriptivism [1]. That variation is the practical upshot for a writer or editor: the level of prescriptivism you encounter depends on which guide you open, so the advice has to be weighed critically rather than followed uniformly [1].
In some language communities, prescriptivism is deeply entrenched
The amount of prescriptivism that feels "right" also depends on the community. In the Arabic-speaking world, stylistic prescriptivism is described as a deeply entrenched aspect of linguistic practice, to the point that abandoning it would amount to a radical break and an admission of linguistic change [3]. This suggests that debates about the proper dose of prescriptivism are not settled by linguistic evidence alone; historical and cultural factors shape how much prescriptive norms are woven into education and everyday practice [3].
Putting these strands together, the evidence supports a conditional answer rather than a fixed number. A measured amount of prescriptivism is defensible where it serves practical communication and stays accountable to empirical findings [2][1], while the field's broader suspicion remains grounded in the view that prescriptivism may not alter language itself [5]. What counts as the right amount therefore shifts with the task and the community, not with a universal standard.
Sources used in this answer
Determining Levels of Prescriptivism in American English Usage Guides
American English usage guides vary considerably in prescriptivism, skewing toward maximally prescriptive advice on many usage problems while still including some prescription-breaking advice.
Linguistic encounters in real world prescriptivism: Acknowledging its place and role
Linguists should recognize and acknowledge the place and role of measured prescriptivism in applied linguistic disciplines, rather than rejecting all prescriptivism as inconsistent with academic objectivity.
Standard language ideology and prescriptivism in the Arabic-speaking world
In the Arabic-speaking world, stylistic prescriptivism is a deeply entrenched aspect of linguistic practice, so abandoning it would amount to a radical break and an admission of linguistic change.
The Role of Prescriptivism in American Linguistics 1820 1970
The notion of prescriptivism persisted in American linguistics from 1820 to 1970 despite intellectual currents that seemed to work against it.
Empirically charting the success of prescriptivism: Some case studies of nineteenth-century English
A mainstream linguistic view holds that prescriptivism does not, and cannot, have any effect on language.