ドイツ語のverlernen（（習い覚えたことを）忘れる）は英語のunlearnよりもポジティヴな感じがする。unlearnはスピヴァクがよく使うので、漠然と近年の造語のように考えていたけれど、OEDによれば、16世紀初頭が初出とのこと。
(a) transitive. To forget or relinquish knowledge of (something previously learned); esp. to put (something considered undesirable) out of one's mind; to give up or discontinue (a habit or practice).
a1500 tr. Thomas à Kempis De Imitatione Christi (Trin. Dublin) (1893) 12 (MED) Withstonde þyne inclinacion & unlerne [L. dedisce] evel custom.1547 W. Baldwin Treat. Morall Phylos. iii. ii. sig. Niiv The best kynde of learnynge is to vnlearne our euyls.1575 T. Vautrollier tr. M. Luther Comm. Epist. to Galathians f. 188 It is to vs no lesse labour to vnlearne and forget the same.1612 J. Brinsley Ludus Lit. ii. 9 Those things which are hurtfull, which they must bee taught to vnlearne againe.1686 W. de Britaine Humane Prudence (ed. 3) i. 2 The most necessary learning for mans life, is to unlearn that which is nought and vain.1738 T. Lediard German Spy xlv. 411 It has been the Business of three or four Years more to unlearn (if I may be allowed the Expression) the ill Habits.1779 Mirror No. 12 As they have learned many foreign, so have they unlearned some of the..best understood home phrases.1813 P. B. Shelley Queen Mab iii. 31 Thou hast given A boon which I will not resign, and taught A lesson not to be unlearned.1864 J. Bryce Holy Rom. Empire vii. 135 The habits of centuries were not to be unlearnt in a few years.1920 Times 9 June 11/2 We were fast unlearning the lessons of the war.1962 R. V. McCann Churches & Mental Health iv. 62 The person unlearns defensive patterns.2010 Independent 8 Dec. 3/3 (heading) We will never unlearn or unknow the great truths that Julian Assange has brought to the world.
Google Books Ngram Viewerで見ると、17世紀から18世紀のあいだは使われる時期と使われない時期が交互にあらわれ、19世紀半ばあたりでグラフは平坦になり、1876年を境にして廃れ出して20世後半まで低調。再び使われるようになったのは、1990年代前後のことだ。
だとすると、unlearnの使用を最近の傾向と捉えるのは、あながち間違っていないのかもしれない。
