Arika may no longer do music festivals, but Episode 4: Freedom Is A Constant Struggle boasted the most sublime music the innovative Edinburgh-based curators have presented since the glory days of Instal, alongside riveting talks, readings and performances. This latest 'kind of a festival or salon' fizzed with an intellectual passion and political fervour sometimes lacking from previous, more drily academic Episodes. Perhaps it helps that the black radical tradition the Episode celebrates is not simply a school of thought, but a wide-ranging cultural programme in which music, art and literature all engage in the struggle for freedom.

Poet and philosopher Fred Moten's theories about the performance of black identity not only provided a starting point for the discussions and talks, but helped contextualise the music and poetry. Friday evening brought together Wadada Leo Smith and John Tilbury, two great musicians whose performances of freedom come from different traditions: free jazz and European improvisation. Short solo sets from each musician help establish their individual approaches, before they come together for the final duo exchange. Tilbury plays more, but does not necessarily lead. The pianist nods to jazz by beating out a rhythm on the piano strings and inner frame, inviting silver free-bop runs from Smith. The overall tone, however, is one of contemplation, with Smith emerging from spells of deep listening to play terse phrases which are jewels of advanced thought. His expert manipulation of the mute creates a range of pinched notes, vocalised smears and breath colours which transport Tilbury's graceful Satie-via-Cage abstractions and inside-piano tones to some nocturnal realm.

Saxophonist Daniel Carter and bassist William Parker came through the 1970s loft scene together, and their fierce duo recordings from that era can be heard on No Business's magnificent Centering boxset. Their Arika performance is a less fiery affair, but the pair haven't so much mellowed with age as expanded their vocabulary to encompass all of jazz, African, Japanese and Native American musics, R&B and the classical avant garde. Parker is one of the great bandleaders and composers of our age, but he's also a master of the duo format, where is incredible bass playing comes into its own. His interaction with Carter is near-telepathic, yielding a succession of gorgeous idea. There is no regular rhythm to Parker's playing, but he works around an indelible pulse, forming a constantly evolving network of bluesy figures and extended chords into which Carter places finely considered alto statements which orbit the harmonic sphere of Ornette Coleman, yet have a haiku-like concision and delicate tone which is highly individual. Carter's stints at the piano are a revelation. While he is not a virtuoso, he has alchemised different schools of jazz piano into a singular style. A fistful of wonky Monk-isms opens out into a cavalier dash around the keyboard that suggests a punkier Cecil Taylor. As he sways from side to side, his arms crossing and uncrossing, Carter's rapid fire jabs form bristling tone clusters which crash and reel over Parker's heavy waves of arco bass. Their final piece sees Parker switching to bamboo flute to play a lament for Sitting Bull, around which Carter's alto weaves subtle magic. A beautiful and utterly transporting set.

Noise provocateur Mattin and philosopher Ray Brassier are Arika regulars, but their piece 'Unfree Improvisation/Compulsive Freedom' feels out of place. The cavernous Tramway 4 is plunged into a darkness and silence that is occasionally interrupted by industrial sounds and the twin assault of a wind machine and blazing high-watt light. With this carefully controlled sequence of noise and visuals, Mattin and Brassier aim to challenge our expectations of what the performance of freedom and improvisation constitutes, but their efforts come across as somewhat empty and nihilistic gesture next to the genuinely inspiring and transformative sets of the other artists.

It matters little, however, for what follows is extraordinary. In what is surely the most successful realisation of Arika's interest in participatory art to date, M NourbeSe Philip invites us to take part in a collective reading of extracts from her poem sequence 'Zong!'. Philip's poems reassemble the legal reports from the court case that followed the 1781 massacre of some 150 Africans by drowning, so that the owners of the slaveship Zong could collect insurance monies. Rather than tell the horrific tale directly, the poem is an act of testimony and reconstruction. The names of the Africans are seeded throughout the text, restoring the identities denied them by the language of the law. Audience members can read the poems in any order, at a pace and rhythm of their own choosing. As the ragged chorus builds in intensity, with Philips, Carter and Smith among those singing, stomping and hollering, I find myself pausing to listen and reflect. It's an incredibly moving experience, sometimes harrowing, but ultimately uplifting.

Having explored various aspects of the black radical tradition, it's appropriate that Episode 4 should end with a performance by a founding figure of the 1960s Black Arts movement, Amiri Baraka, accompanied by one of free jazz's original and greatest bassists, Henry Grimes. At 78, Baraka is a quieter figure than the young revolutionary who declaimed over Albert Ayler's screaming saxophone on Sunny Murray's 1965 classic Sonny's Time Now, but his anger and wit remain undimmed. 'When I was a kid I used to read a lot of Chinese and Japanese poetry, haiku,' he explains at the beginning of one particularly memorable sequence, 'So I came up with haiku for black people, low-ku'. These short, mostly metrical and rhyming verses give voice to pithy and laconic digs at the hypocrisy and stupidity of American elites, with Grimes' hip walking bass adding a swing to Baraka's swagger. Baraka ends with his lengthy response to 9/11, 'Who Blew Up America'. Attacked at the time for its perceived anti-Semitism (to my mind it's simply anti-Zionist), the poem forces America to consider its own legacy of terror, offering a litany of imperialist outrages from the slave trade to the CIA's backing of oppressive regimes in South America. Baraka's accusatory refrain 'who, who, who?' is left ringing in our ears, reminding us that Scotland has its own imperialist crimes to acknowledge, principally its role in the slave trade. For all his anger, however, Baraka never hectors, instead using wit, intelligence and rhythm to launch his revolutionary invective. Grimes, meanwhile, is a quietly powerful presence, rock solid but exploratory on bass, and keenly atonal on violin. Together, they bring a remarkable weekend to a thrilling conclusion.

Daniel Carter and William Parker

Daniel Carter

Wadada Leo Smith

M NourbeSe Philip - Zong!

Amiri Baraka and Henry Grimes