As most readers will know, Johannes Bronkhorst (1985) and Philipp Maas (2006, 2013, see also this post) have recently cast doubt on the traditional idea that the Yogasūtra has been authored by Patañjali and then commented upon by Vyāsa in the Yogabhāṣya. Some authors (such as Dominik Wujastyk, Jim Mallinson and Jonardon Ganeri, if I am not misunderstanding them) have accepted Maas’ view. Others don’t accept it without offering much explanation (see Shyam Ranganathan’s few lines in his Handbook of Indian Ethics). Federico Squarcini engages in his translation and study of the Yogasūtra in a longer discussion of this view,
but unfortunately in Italian. Since a student asked me to do so, I am here going to highlight the main points in Squarcini’s presentation, hoping that they might be helpful also to other readers (pp. cxi–cxxv):

1. It is true that the early commentaries refer to the YS-YBh complex
2. It is also true that Vedavyāsa is mentioned as author of the YBh only relatively late, possibly for the first time in Vācaspati’s Tattvavaiśāradī
3. Furthermore, it is only with Mādhava’s Sarvadarśanasaṅgraha that people start distinguishing Patañjali’s from Vyāsa’s authorships.
4. Nonetheless, Maas’ argument is too dependent on the manuscript tradition, which has the two texts together, but is extremely recent (for Maas’ reply that recent manuscripts must depend on earlier models, see this post).
5. Squarcini also mentions in a footnote that Vyāsa himself mentions the name of Patañjali (but see a further post on this blog for D. Wujastyk’s answer thereon).
6. After having, in his opinion, weakened Maas’ arguments, Squarcini lies down his own one in favour of the existence of a separate YS: The text is highly and consistently structured and locates itself within a net of intertextual references, which the author of the YBh partly ignores. Squarcini claims to have identified the deep structure of the YS and distinguishes several subtopics within the main topics, signalling them as such in the Sanskrit text and in the translation. Accordingly, Squarcini highlights some key sūtras of the YS which work as if they were adhikaraṇasūtras.
7. Accordingly, Squarcini’s translation does not need to borrow words from the commentaries, as most other translations.

The forelast point is the most relevant one and it is substantiated in the first hundred pages of Squarcini’s introductory study. I will highlight here some of the elements which struck as most interesting. Readers are alerted that this is nothing but my summary, not (yet) validated by F. Squarcini.

• The question of the alleged YS-YBh unity has an impact also on the alleged proximity of the Sāṅkhya and Yoga systems. Squarcini argues against it on the strength of texts more or less coeval to the YS (e.g., Milinsapañha, Visuddhimagga, Madhyamakahṛdayakārikā, see p. lxxviiff), including the Nyāyasūtra, which ignores Sāṅkhya but discusses at length Yoga.
• Notwithstanding some affinities, e.g., the use of the words puruṣa, prakṛti and kaivalya, the YS understands them very differently than, say, the Sāṅkhyakārikā (pp. lxxxi–lxxxii).
• The dualism of the YS is, unlike that of Sāṅkhya and also (although Squarcini does not spell this out explicitely) of the YBh, is not an ultimate dualism. pusuṣa and prakṛti will not remain distinct until the end. Rather, the dualism of the YS is an “eliminative dualism” (the label is by Paul M. Churchland). Squarcini here elaborates on hints which can be found in Adolf Janacek (1951) and in L.W. Pflueger’s Dueling with Dualism. Revisioning the Paradox of Puruṣa and Prakṛti (see pp. lxxxvii–cxi)