Why does the following sentence use the word 'knowledges'? [closed]

Consider the following question given in an English class for high school students in Myanmar:

Mg Mg has computer knowledge. Tun Tun has computer knowledge.
(Given Answer word is Both _______).

We have to answer this question beginning with Both. One of the teachers gave his answer like this :

Both Mg Mg and Tun Tun have computer knowledges.

I think that the 's at the end of knowledge is unnecessary. Am I correct?

Solution 1:

You are correct.

Your teacher is not exactly wrong, but he is also not exactly right. Namely, in most contexts, native speakers would not pluralize knowledge in that sentence. Only in very specialized academic contexts would knowledges be appropriate.

Most dictionaries do not record knowledges, but the OED does, in several meanings. I will reproduce all of them, but it's 9.a. that seems relevant to your sentence.

II. The fact or condition of knowing something.
4.
  c. With of. The fact or state of having a correct idea or understanding of something; the possession of information about something. Also with indefinite article; formerly also in plural.

^{…
1670     T. S. & A. Roberts Adventures Eng. Merchant 146 They do it by the Knowledges that they have of Nature.
…}

  d. As a count noun. An act of apprehending something with the mind; a perception, intuition, intimation, etc. rare.

^{…
1626     T. Hawkins tr. N. Caussin Holy Court I. 123 To proceed..by such knowledges, as are common, with brute beastes, and forsake those of men.
1825     S. T. Coleridge Aids Refl. 160 It is the office..of Reason to bring a unity into all our conceptions and several knowledges.
a1856     W. Hamilton Lect. Metaphysics (1859) I. iii. 57 These two cognitions or knowledges have, accordingly, received different names.
1920     M. Austin No. 26 Jayne St. 241 Little knowledges of him like this came to her out of their enlarged intercourse, for they saw one another almost daily.}

6.
  a. Chiefly with of. The fact or condition of having acquired a practical understanding or command of, or competence or skill in, a particular subject, language, etc., esp. through instruction, study, or practice; skill or expertise acquired in a particular subject, etc., through learning. Frequently with indefinite article. Formerly also with †in or infinitive.
^{In quot. 1787 in plural, indicating competence in more than one field.}

^{…
1787     ‘P. Pindar’ Lyric Odes to Royal Academicians (ed. 5) iii. 9 With scarce more knowledges than these, He earns a Guinea ev'ry Day with ease.
…}

III. The object of knowing; something known or made known.
9.
  a. As a count noun. A thing which is or may be known; esp. a branch of learning; a science; an art. Usually in plural.

…
^{1935     Times 5 Jan. 16/5 In the typical school to-day the time was so filled up with the learning of traditional knowledges and skills that little time was left for anything else.
1994    Appl. Linguistics 15 127 A key part of Foucault's work is his analysis of how various knowledges and disciplines—medical..penitential, sexual, and so on—normalize social institutions and practices in society.}

For example, the following books exist:

Knowledges: Historical and Critical Studies in Disciplinarity (1993, here).
Indigenous Knowledges in Global Contexts: Multiple Readings of Our World (2000, here).
Feminisms in Geography: Rethinking Space, Place, and Knowledges (2008, here).

If you search Corpus of Contemporary American English (COCA), you will find that out of 214 hits, all but two come from academic works. In the British National Corpus (BNC) it appears 22 times, and it seems that here, too, almost all of them come from academic publications.

Thus, knowledges does get used in academic contexts, but it is uncommon otherwise.