Opinion: while many architects are designing slippery "architexture", Norman Foster and Alejandro Aravena are unlikely allies in the pursuit of real architecture, says Will Wiles.

Two architects, two different practices. One specialises in luxurious mega-projects and planetary – interplanetary! – ambition: skyscrapers, hub airports, spaceports. The other delivers modest, resourceful, community-based projects, some of which are left to the residents to finish.

Two architects, two different visions for architecture. One speaks of its revolutionary, transformational potential, urging architects to grasp some of the most difficult and pervasive problems of our age. The other is limited and pragmatic, and says that architects don't really have the ability to change anything.

Can you match the practice to the vision? It's a trick question, of course. It's Lord Foster, whose practice now works on the scale of city-region, nation-state and near-earth orbit, who presents the starkest view of architecture's scope for effecting change. "I have no power as an architect, none whatsoever," he told the Observer's Rowan Moore in a searching interview published on Sunday. "I can't even go to a building site and tell people what to do."

Over at the Guardian, however, Chilean architect Alejandro Aravena – director of the 2016 Venice Biennale – calls for architects to break out of their disciplinary boundaries and engage with issues such as "immigration, water, land capacity, waste and so on."

"We want to understand what design tools are needed to subvert the forces that privilege individual gain over collective benefit," he writes, launching his ambitions for the biennale; "to highlight cases that resist reductionism and oversimplification, and do not give up on architecture's mission to penetrate the mystery of the human condition."

The presentation is very different: old hand versus firebrand. But in fact Foster and Aravena's remarks have a lot of in common. Foster says that the way architects can make a difference is by advocacy, demonstrated by his practice's late enthusiasm for a new London hub airport on reclaimed land in the Thames, and more recently a vision for a drone network spanning Rwanda.

Aravena talks about architects learning the language of other disciplines – economics, security, the environment – and applying design tools to the problems facing those fields. Both men are fundamentally urban in their thinking. Both men are talking about moving architecture out of the shallows of aesthetics and into deeper water, be it infrastructure or inequality.

In my last column, about whether architects should design prisons, I said that good intentions counted for nothing, and that even the most worthy design was doomed to compromise if it was on behalf of a generally unjust and corrupt system. So is there much potential to go beyond the confines of merely "designing a building" and changing systems themselves?

We should be sceptical. When firms like Foster's and Farrell's develop schemes for elaborate transport hubs and the like, you're watching large commercial enterprises gently pitching for the sweetest contracts in the global construction market and not necessarily keeping the common good at the forefront of their minds as they do so. When hubs are worth hundreds of billions of dollars, every problem begins to look like a hub. Hubba bubba.

As for Aravena's interdisciplinary architectural renaissance men and women, perhaps the generous approach is wait and see. I'm truly curious to find out, come the biennale, how much of a difference architects can make against colossal macro issues such as economic inequality and global migration.

That might sound a bit jaded. Architects are mostly intelligent, practical, conscientious people, and tend to bring a lateral approach to problems, even if that problem is simply extending a kitchen. In recent years the quite unexceptional idea that architects might be able to make valuable interventions outside architecture has at times whirled out of control into the TEDly giddiness about "design thinking", which was largely the product of a few innocents experiencing a rush of blood to the head when they learned how much consultants get paid.

However, Aravena is a sensible man and there is nothing fundamentally wild-eyed about his proposition that architects should listen to other disciplines and take into account broader social and environmental frames as they approach projects. Heaven knows there are other professions that would do well to behave this way – I'm looking at you, economics.

What Aravena and Foster share, it seems, is the knowledge that without alertness on their part, what they produce will be nothing more than a pretty sheath for other people's ideas. Both are surely aware of the receding role and status of the architect. Even the "built environment" is increasingly out of their influence.

"[R]epeatable formulas make most of the space in the world," wrote the theorist Keller Easterling in her magnificent essay "The Action is the Form" (Strelka Press, 2012). "These buildings are not singularly crafted enclosures but reproducible products – spatial products. The discipline of architecture is only responsible for a trickle of the world's spaces while a fire hose blasts out the rest… Architecture is making the occasional stone in the water. The world is making the water."

Aravena calls for a rethinking of the role of the architect, and new language to express that role. What could we call the new, expanded, discipline that Foster and Aravena both appear to have in mind? Perhaps we don't need a word for it at all – it's architecture, behaving as architecture should.

What might be needed is a word to describe the side of the practice that doesn't aspire to these broader, more important goals. The side that mostly only exists to give a sheen of design to routine neoliberal spatial products. Architecture as surface and appearance, architecture that is camouflage and alibi. This slippery stuff, which feels like architecture but isn't, could be called architexture.

In a world filled with architexture, it's pleasing to see architects examining their purpose, and finding the edge and role of the real thing.

Will Wiles is the author of two novels with architectural themes: Care of Wooden Floors, in which a man is driven mad by a minimalist apartment, and The Way Inn, a horror story set in an anonymous chain hotel. He is contributing editor at Icon magazine and a freelance design journalist.