What I thought would be useful for us to pick up on, is how we look at cities. And in a way to think about the issue of theory and the value of looking at history. We need to know what theory is, as well as what different theories there are. There are different ideas about what theory is. I think for me the most helpful way to distinguish that is to think about really big meta theories, if you like. Ideas that are kind of all embracing, where there are large models and paradigmatic ideas. Ideas about neoclassical economics might be a good example where the logic of the market becomes a central principle which leads to theoretical and research tools, ideas of class which we associate with Marxism and Neo- Marxist ideas with the other kinds of ideas, lots of post-structuralist form of ideas.

Different ideas have got different origins and it’s important to train our minds to understand what those differences are. Because they do make a difference to how we see cities.

I find it very important and the reason why it is important for practitioners to understand theory is that, depending on when you were trained and where you were trained, you were probably exposed to different kinds of theoretical ideas. And because people, when they are training often think quite closely about theoretical ideas, they forget, later on, when they begin to start practising that those are ideas that shaped how they think.

Those are ideas that give a formative articulation to the way they define problems, what they see the problems as and what they think might be solutions.

When you are in a room full of people, as most of us are when we are talking about cities, whether we are working with civil society people, whether we are working with communities and especially if you’re working in places where there are lots of trained professionals, people come from very different theoretical perspectives.

Sometimes what you think is a conflict of personality is actually a conflict of your theoretical base. Theories aren’t the same as your normative base or value base. I’ve already given some example of, what I think different theoretical ideas are as they relate to cities.

And the big ones would be some of the earlier ideas of cities which come out of the Chicago school. Which are schools of ideas about modelling which come out of logic from ecology actually.

There is some kind of state that is somehow a way that if we put pressure here, it relates to a pressure there. There are old models of cities like the Burgess and Hoyt that some of us grew up on, which in some senses predict that the overall structure of cities have their origins in ecological thinking.

It’s a system’s thinking. We’ve seen a return to that kind of thinking today. The one that has probably had the most influence in the last 50 years has been Marx and the ideas that flow from Marx. There’s the idea that there is a central logic of capital in a way that money operates in a system. You have labour and you have capital and depending on the flows of capital, Marx talks about very different kinds of processes which impact on cities In order to continue to make money, capital has to continue to expand.

But there is also a contradiction because in order to make money for individuals you’ve also got to consolidate.

Some people like David Harvey then talk about what that means for money.

People have worked very systematically following that. People like Smith and others, have worked on how that impacts on the city. So basically the idea is that you will get investment in different circuits of capital, different places to put your money. So when money isn’t flowing through resources and it has stopped making as much profit as it might, it will switch into the built environment. A lot of people critiquing that say that it is not very helpful to understand the informal economy. Some people say that the informal economy is a separate circuit of capital. But others say it is all part of the same system. Other people who I think of as Marxist have big theoretical ideas. Or are at least some kind of a materialists, political economists – if you like don’t focus as much on money but they focus on the fact that there’s a working class set of people who have nothing to sell but their labour.

So they are no longer agrarian and are no longer dependent on their land but they have to work. That was the idea what Engels was very keen on and his ideas were about how the working class should organise and whether or not they should participate, for example, in home-ownership, has probably been one of the most influential debates. This issue of home-ownership and its relationship to a working class organisation has been a prevailing idea. When we talk about contemporary literature that is very influenced by the Marxist ideas and continues to be, either they adopt them or they are in opposition to them. So think of much of the literature on gentrification. Why do we see re-investment in particular parts of the city.

There are very different kinds of ideas about that. Tied to this is the question of home-ownership, whether it is a good idea or a bad idea, an example of where theory lands. What’s most useful for me is to untangle that we have different theoretical ideas. So that we don’t get confused and have fights like religious views It helps to know that somebody in the table is a Muslim, a Buddhist or a Jew. Not because you are going to change each other’s minds but you recognize that the way that you see the world, has different starting points. And that enables you to learn from each other sometimes, it enables you to define what you think, because you do see something differently and you don’t agree on everything. But also sometimes to see things from somebody else’s point of view. So while I’m saying “Don’t try in the early stages, to be appropriate about how you make theoretical contributions”, I’m also saying that it is worth trying to have a set of building blocks out there that exposes you to different theories.

And certainly for urbanists it’s helpful because we come from such different disciplinary bases. I am a Geographer, you are a Planner, you are an Ecologist, you are an Engineer, you are an Architect. So we already have different disciplinary sensibilities and yet another sieve. We talked a little bit about theory. We talked about how different disciplines use different theoretical ideas. Typically I talked about how ecologists would use systems thinking. Engineers also come out of systems thinking and some of the new complex data people are very systems oriented in their world view. Similarly many economists come out of the neoclassical understanding of theory. If they are on the right or if they are on the left, they come from a Marxist to a neo Marxist interpretation. Sometimes you recall all of the people who do that kind of theoretical work- Structuralists, in some senses.

Then there’s a whole group of people whom we would call post structuralists. We talked sometimes about the cultural turn. There is a group of scholar for me, who do really important work, who are historians who don’t fit neatly into this. It’s not that history isn’t a theoretical discipline. Although it has had that critique levelled at it but it tends to get much more concerned with evidence, narrative, storytelling and the evidence for that. History really matters for understanding cities. Some people talk about historical turn where there has been a growing recognition that it is actually very important to understand the urban past. It is a very easy case to make because it sounds obvious when you say you want to solve contemporary problems and you are trying to make sure to build better cities for the future.

It makes an awful lot of sense to understand how you got to be where you are and why the systems which are in place, are there, before you start to change things. But in fact we haven’t done that. The skills that are required for undertaking urban history are often marginalised and people who study the history of cities do so in a way that are not especially useful for contemporary practitioners. There’s a sort of dissonance between a lot of work done on cities as opposed to a historical understanding of some of the processes which are in at the moment. For example, There is not a lot of work on the history of sanitation or the history of building codes.

There is quite a lot of work done in some parts of the world on really interesting questions like the origins of city politics and the mafias which lie behind certain kinds of decisions which get made. Certainly, something like the US is extremely well understood in that Sometimes using, what I would call little theoretical ideas, the smaller scale, not the meta theoretical idea that we talked about, like the Regime theory, have quite often gone back to say, “What are the coalitions of power here? How do these people come to be in the city? And whose interest correlates in order for decisions to be made?” So how do we explain that an area that was supposed to be protected actually got a major development on it. It wasn’t just one developer who went in, There was a coalescence of interests that came together, because actually people who were living there were being brought out somebody who had just invented a new technology or had railway interests These things came together.

So they are are regimes of power and that is part of a theoretical idea that has some historical traction in the way that it is undertaken. To some extent, some of the work that’s been done now on systems theory can have a historical inclination in the sense that we need to understand the multiple components and the way that they interact. And as soon as you do that, of course, not everything interacts at every moment, you have to go backwards because systems thinking is quite present at the moment there is a return to historical work.

The difficulty is again, when we begin to try to understand cities in a global south, and this is where the general question is, are the theories that we have at the moment, up to interpreting the global south? There’s a big debate about that question. But there is absolutely no question that there is insufficient historical material about the places that we are now desperately  trying to engage with. We simply don’t have the histories in any kind of depth across enough different scales, enough different sectors. South African cities are probably the most well studied of any, outside of perhaps Egypt, from a historical perspective. And their fundamental things that we know nothing about. How did the land tenure system come to be in place? What’s the history of the zoning codes. Where actually are the sewers? Why is it that at certain points the financial system change? Why did they choose that financial system? Things that are really really important before you start to make that sort of amendments, but we don’t have that kind of information on. For other cities, the lack of historical material is even worse.

There are really crucial kinds of questions where we have no record of population change. We don’t know when people began to come into the city. We have no understanding of who in fact, the really powerful players are in the city and what the economic base is. We don’t know why they managed to get that purchase. So we start to try and change things. We begin to start engaging in things where we don’t know the real political dynamics are So the informal land markets are probably the best example of that. So if you think of an Indian city, I’m quite sure that you will know that there are major interests that control large informal settlements that are probably very reluctant to allow development to come in for very particular kinds of reasons.

Yet we’re signing up to use sustainable development goals, which say we can have waste collection, water collection. We can have personal bunch of services but the political ramifications of that can’t be anticipated unless you understand the underlying political economy of the city. And that political economy is based not just in the financial systems but also in infrastructure and the social systems, in any number of different variables and so we need a whole hoard of historians to be out there documenting and presenting that material for us. An even bigger problem is that in a lot of cities that are undergoing the fastest transition the ones where poverty and inequality are greatest, where there are the most exciting opportunities to change things, it’s not just a case of going to the archives and finding those records because they haven’t been kept.

And so this presents a really really difficult challenge for us because if you have a city like Paris, not only do you have fantastic contemporary data but you have a full archive, a full municipal scale archive, a full local archive. You have university archives, you have newspapers and everything is terribly neat and its ordered. All you have to do is go and read it. Spend the time, do the analysis and you can actually come up with something quite sensible. When there is no obvious place where this record has been kept, it is a much much more difficult task.

We’ve got to start not just undertaking some in depth narrative interviews with people, which we must do quickly while our elders are still here who can tell some in depth stories that we need. But we also need to start protecting the resources about the city and it’s evolution for future generations. So i’m thinking here for about photographs, I’m thinking here that our communications in city hall are no longer archived because many of them are emailed. So what are the protocols that we have? Both the formal and the informal spaces. So I would make a very strong call for us to begin to start looking at history.