I am afraid that I do not have the ability to give a political defence of the work of Adam Curtis, but I would say that the thing that most attracts me to his documentaries* is often not so much any political point being made but the sheer verve and skill of the filmmaking on display. I find watching his work thrilling (which could be seen as dangerous in its seductiveness too) such that it papers over the cracks in the narrative where the critical analysis of the ideas should be stronger. Its more about flow and often cheeky juxtapositions of music and imagery, especially in the later non-televised, made for the internet works Bitter Lake and HyperNormalisation, and especially the installation piece It Felt Like A Kiss where the omniscient narration is minimised or even entirely absent and replaced by pithy surtitles under imagery that may or may not bear any actual relevance to the action, but are more free-associational in their linkages.
I would also argue that despite tackling extremely politically relevant subjects, Curtis's work has always been less about the 'flow of historical events and figures' (though he often uses such figures as structuring frameworks in the televised BBC series) than about the psychological thought processes behind the events. What people were thinking that made them approach the wider world with a kind of lack of humility towards upending things (Usually a classical British or American education in the best private schools! Only emphasised more when students come from around the world to study and internalise specific agendas to then return to their own countries and put into practice, with more or less success in doing so. This might be getting into the limitations of 'soft power' and 'Western educational influence' that are more implicit in the works however) and what caused them to take the 'real world' actions that shaped the world we all have to inhabit today. From terrorists, to Blair and Bush, to the men behind faceless think tank corporations, all have brought certain agendas (that may only have ever existed within their own minds) to bear on the world, often with bloody consequences. Its usually all to do with a desire for constant 'change' regardless of whether desirable or not. Which kind of gets into Curtis's later argument about 'non-linear war' that is deeply tied into media and how it presents authority figures, as shown by Putin acting in paradoxical stage-managed ways to always put any opponents on the back foot, which of course Trump later took to even more absurdist extremes.
In that sense the early documentary series purely focusing on psychological topics - Pandora's Box, The Century of The Self - are key, because Curtis has not really changed approach even when tackling subjects like the 2008 banking crisis or Iraq. Its taking a "what the hell were you thinking?" approach and then trying to illustrate both the cultural morass where people who eventually came to have power to manipulate things first began to formulate their ideas (often the mid 20th century post-WWII ideas of freedom, the medicalisation of emotional 'aberration' and psychiatry getting elevated into being 'cure all' solutions for normal human feelings of lack, despair and just sadness in general) and trying to try and point fingers at a 'Patient Zero' (in a playful manner, though it gets much less humourous when the actual 'Patient Zero' monkey in the rainforest beginning the AIDS era turns up) from which all of the dreadful ways of thinking that have so twisted the modern world may have sprung up.
That does get Curtis into the territory of conspiracy theories and ideas of cabals of people working to destabilise the world to fit their own blinkered agendas, and I think he is well aware of that, and how scary yet amusing it can be, in the nebulous use of overarching terms like "them" and "but that's just what they want you to think" throughout a lot of his narrations. But the thing that pushes him away from becoming just another Dinesh D'Souza for me (aside from the political leanings) is that Curtis appears enamoured/enraged not just by how people in positions of power have had shadowy agendas but more that they have screwed up implementing their shadowy agendas so much that they have actually fostered the chaos that they were putatively attempting to pre-emptively counteract! (
"Or is that just what they want you to think?" ) Whether that is on the international stage (and especially in the Middle East) or in application of psychological behavioural theories to the population at large.
The average Adam Curtis documentary feels both despairing at the lunatics in charge of the asylum but also seems to find some sense of consolation in the way that even those in power have little sense or idea of how their agendas are going to play out in practice. The behaviourists of the RAND corporation in the mid 20th century would probably never have imagined how their ideas would be picked up on to shape the world by people with their own agendas. By that extension it is similar to the obvious lack of forethought in the invasion of Iraq for the consequences that would follow come about from simply wanting a simple bad guy to hold responsible for 9/11 (to divert attention from Saudi Arabia; and to consolidate a hold on oil; and to finally get rid of a dictator in Saddam under another pretext), which ironically only caused a new wave of Islamic terrorism to fill the power vacuums that were left in getting rid of the old wave of (mostly Western created) dictators.
The scariest thing about the world from an Adam Curtis documentary is that nobody can predict the chain of consequences that might follow from their actions (which might suggest a bit of humility is needed from politicians in terms of making sweeping changes), and it is only scarier in recent years when politicians such as Putin and Trump have put 'dangerous unpredictability' at the heart of their policy making to such an internationally destabilising effect (arguably the banks too).
It is also why I come at Adam Curtis's work as being quite Ballardian in its own way, in the way that it is a creation made by poring through stock footage, B-roll and music libraries to create a sense of meaning and a 'new world' out of a messily chaotic one where nothing makes (emotional or logical) sense. Curtis's narration often makes him feel a bit like the "T-figure" in The Atrocity Exhibition cutting up the 20th century and collaging it together again to try and make it 'more acceptable' in a psychological way
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* And yes, the definition of 'documentary' as unbiased and purely objectively critically analytic is a whole area for debate. It is already tricky enough with your staid and classical 'talking head' style documentaries, where questions of who is being interviewed and how much time they are given compared to other interviewees, even how they are edited together with other footage or interviewees (where the next person we cut to may confirm, or completely counter, the previous person's comments!) reveal various agendas of the documentary makers. Or the 'selection bias' of what particular subject (or facet of a larger subject) is chosen to be focused on, and thereby elevated. And there are many other selection biases, visible and invisible which took place in the early stages of production. Even if those biases are approached as sensitively as possible, they can still be limited to who agrees to participate or who is alive to be interviewed, and so on!
But it has only become even more difficult to assess in an age of first person, self-shot vérité 'documentary footage' (which I would perhaps argue are better classed as 'primary source footage' rather than documentaries in themselves, because a documentary by its very nature is something which is taking raw footage and shaping it to a particular agenda. Although even that is more fluid now that individuals do not entirely have to wait for a benign documentarian to come along to shape their story and can now shoot and edit their own narratives themselves if they so wish), which both exist simultaneously to the purely activist (and extremely politically agenda driven) films (i.e. anything by Michael Moore or Dinesh D'Souza. And it could be argued that these documentaries are just glossier versions of people sitting in their bedroom ranting to their webcams, just with a bit of added CG pizzazz, actors and a theatrical release to illustrate their points better) which appear to have caused the upsurgence of the highly glossy 'dramatised documentary' in its turn, where we get actors re-enacting events, or even speculating on future events that may occur (The Age of Stupid comes to mind, with its shrill warning from the future from Pete Postlethwaite's figure)
All this is to say that the only bright spot of the current world situation is that I am looking forward to the next Adam Curtis piece that talks about this, and probably puts the events of 2020 in the context of his previous films, which had already talked more and more about the shift of economic and political power to an ever smaller group of people even before the pandemic caused mass unemployment, the closure and 're-thinking' of industries thought integral to the economy, and certain sectors making more money and consolidating power more than they ever have. Although in some ways he was already talking about all of this decades ago, especially the retreat of politics in the face of the rise of international, unaccountable, 'unaffiliated' (in good and bad ways) corporations promising the world (and more importantly the lifestyle) to those who buy (in to) their products.