There is an illuminated quotation from The Unnameable hanging over a passageway, a symbol of how an absurdist script that attempted to reconcile audiences with the experience of living in an era of godlessness and environmental threat has become a vague gesture of determination. One hundred yards along from it, there are companies handing out flyers but refusing to take other flyers because 'the environment'. It shouldn't be necessary to explain irony to performers, but bourgeois hypocrisy and green-washing runs deep in theatre.

The Fringe is beginning in earnest now, and that elusive spirit is bathed in cynicism and disappointment. Alex Hughes is at the edge of George Square, in the Box, trying to find The De Super Nova, a spaceship which might represent the last great hope for human survival. Science-fiction is becoming a growing concern at the Fringe, and Hughes is chasing its philosophical potential.

'We must always discuss things and we must sometimes force ourselves to keep our minds open,' he observes. 'People will always gravitate to a more collective shared experience because there is a warmth in that, but also because we like to know what other people think too.'

Kirsten Vangsness: Mess / credit: Darrett Sanders

The De Nova Super is dystopian, alienating and reflective – despite being shot through with clowning. Perhaps this distinctive combination offers additional layers to the generic experience of 'liveness' in performance: a cognitive dissonance as the collision happens in real time and space.

'We definitely endeavour to provoke emotion and discussion, but sometimes we do that by not always answering the questions the show asks,' he continues. 'There are mysteries for the audience to solve, as there are in life.'

And despite the darkness in the show, and the deep space of an absurd universe that surrounds the two protagonists of The De Nova Super, Hughes still seems optimistic about the potential of performance. This isn't the marinade of misery that the Fringe spirit could embrace. What about the rumours of comedians selling out every seat in every show, and still finding themselves ten grand in the hole? And hasn't the Fair Fringe insisted it is time to talk about exploitation – and does that account for the mysterious disappearance of most of the C Venues?

Despite having a show called Mess and conjuring up powerful women from the past in Cleo, Theo and Wu, Kirsten Vangsnsess maintains that there is a freedom in making theatre. 'Mess came about because I wanted to make something that I didn't have to bother anyone else about or rely on anyone's schedule to create,' she explains. 'With filming Criminal Minds, this format was a brilliant way to make sure I could still perform and also deal with my crazy schedule because I would just be rehearsing with myself.'

Mess is an undeniably idiosyncratic show, which relies on Vangsness' charisma and has a bravura performance holding together her wild associations and pleasure in linguistic fluidity. Yet she still holds out an ideal of theatre that is inclusive. 'I'm a theatre girl through and through, and I think the nature of creating theatre is community building.'

Both Vangsness and Hughes affirm a belief in the urgency and vitality of performance, as a location for conversations, an opportunity for freedom of expression and a foundation for human connections. Even though they deal with the darkness – environmental catastrophe and, in Cleo, Theo and Wu, an alienated young woman – they call upon theatricality to offer, if not answers, guiding questions.

In delving into dark topics – or allowing free reign to a convoluted thought process, they suggest that there is an alchemical transformation somewhere in the artistic process; that the stuff of life, even the alienation, can become a message of hope through creation. Like some interpretations of Aristotle's catharsis, the purging of emotions in performance can offer redemption to the audience.

Rowan Rheingans: Dispatches on the Red Dress

Rowan Rheingans' Dispatches on the Red Dress presents a similar transformation, with a twist at the end that becomes a beautiful allegory for how the survivors deal with historical atrocity. Using her musical talent – Rheingans is an award-winning folk musician – she considers the mundane relationship with her grandparents and their experience of living in Nazi Germany to reflect on how history doesn't always teach tolerance, but that resistance can be subtle and telling.

Rheingans' heritage (she is of Germany ancestry and British residency) places her in a liminal position, with memories of German Christmases with her grandparents and an ongoing connection to their homeland. While they were at the edges of the horror during the Second World War, Rheingans observes that experiencing prejudice has not necessarily made them more inclusive, and their personalities remain shaped by wartime pressures.

Calling it 'a musical essay', Rheingans places ten songs – using banjo, fiddle and guitar – at the service of an impressionistic reflection on 'my fears and worries about the world now.' She comments on 'how horror and beauty co-exist' and the titular red dress becomes an eloquent symbol of resilience, but also how the prejudices of the past are sewn into the celebrations of the present.

Although the show has been made with co-writer Liam Hurley, Rheingans comes from a music rather than theatre background, and much of the script concerns the power of social dance and music, while she draws on the story-telling that is a large part of contemporary folk music traditions. Her relaxed style doesn't reach for the intensity or humour of The De Super Nova or Mess, but allows scope for consideration, and makes subtle, trenchant points about how obnoxious political opinions can pass through the generations.

Perhaps Red Dress offers a solution to the puzzle of the Fringe, even though it does attack weightier topics in its gentle, domestic aesthetic. The bad stuff becomes the raw material for something more joyous and hopeful, and the act of presenting the horror of deep space or personal alienation is an opportunity for the audience to experience terror and find the humour and possibility within it. Maybe the paranoia and pain of the Fringe, experienced by artists, critics and people just trying to get to work on the Royal Mile, can be transformed into beauty and freedom through the act of artistic expression.

Rowan Rheingans: Dispatches on the Red Dress, Scottish Storytelling Centre, 15–26 Aug, 6pm, £12 (£10).

The De Nova Super, Assembly George Square, until 26th August (not 12, 19), 3pm, £10–£12 (£9–£11).

Fempire: Cleo, Theo & Wu, Assembly Rooms, 16–17, 19, 22–23, 8.15pm, £10–£11 (£9–£10).

Fempire: Mess by Kirsten Vangsness, 15, 18, 21, 24, £11–£10 (£9–£10).