Ah Foucault…There is a lot to grapple with in Society Must Be Defended, and I will do so below more for my memory in writing a dissertation than anything else, so be warned!
I love that it starts out with Foucault’s critique of Marx — there must be more out there I haven’t found in terms of that critique, but this really helped me think through the distinctions as it has always seemed to me that the two could well complement each other. I suppose they still can if broken into pieces and rejoined, but I have a much better sense of how different Foucault’s project is.
He argues that Marx, or any other similar over-arching theory such as psychoanalysis, “provided tools that can be used at the local level only when … the theoretical unity of their discourse is, so to speak, suspended, or at least cut up, ripped up, torn to shreds …”  Why is that, particularly in thinking about theories that have liberation as their goal? Because their effort to unify knowledge into a single framework of understanding is the problem, particularly the way that theoretical frameworks such as Marxism see themselves as a science. This sets up an ‘aspiration’ to power, where they decide what kinds of knowledge are legitimate and which are not with the aim of organising them, filtering them, putting them into hierarchies to create a body of ‘true’ knowledge. Foucault argues that this is done primarily to allow Marxism to benefit from the power that Western society has granted scientists and the scientific paradigm, rather than to actually create a Marxism that is scientific. Thus Marxism oppresses.
In opposition to Marxism’s (or psychoanalysis’s, or liberal economist’s or etc) subjugation of various knowledges, Foucault’s project is to liberate these various subjugated knowledges: “to set them free, or in other words to enable them to oppose and struggle against the coercion of a unitary, formal, and scientific theoretical discourse” . His archeological work seeks to understand these formal scientific discourses, and his geneological work to liberate the local knowledges that have been subjugated by them.
Got it. Fundamentally antithetical to Marx in its theory, and I couldn’t ask for a clearer definition of the archeological v the geneological. (There’s also the fact that he ends the lectures with socialism is racism, but more on that later.)
One critique before moving on, Foulcault writes: “When I say “subjugated knowledges” I am also referring to a whole series of knowledges that have been disqualified as nonconceptual knowledges, as insufficiently elaborated knowledges: naive knowledges, hierarchically inferior knowledges, knowledges that are below the required level of erudition or scientificity.” I applaud this project of course. My problem with Foucault is always that he writes in a way that cannot engage in dialogue with these knowledges, but can only ‘unearth’ or worse ‘discover’ them. Please note the complete absence of the actual people who hold these ‘knowledges’, whatever those are when separated from their human beings, both from these lectures and presumably from these lecture rooms. Meh.
The question here is what is power, but as Foucault writes: “‘What is power?’ is obviously a theoretical question that would provide an answer to everything, which is just what I don’t want to do” . Instead he wants to try and understand how it operates. He starts with liberalism and Marxism which he believe share the common feature of ‘economism’ stemming from a juridical understanding of power. In liberalism, “power is regarded as a right which can be possessed in the way one possesses a commodity” , it can be traded, taken, given up by political contract and etc. To take that to its conclusion, “There is therefore an obvious analogy, and it runs through all these theories, between power and commodities, between power and wealth” .
In Marxism, you have what Foucault calls the “‘economic functionality’ of power … to the extent that the role of power is essentially both to perpetuate the relations of production and to reproduce a class domination that is made possible by the development of the productive forces and the ways they are appropriated. In this case, political power finds its historical raison d’etre in the economy” .
He moves away from these economistic theories, exploring the ideas that “power is not something that is given, exchanged, or taken back, that it is something that is exercised and that it exists only in action,” and that “power is not primarily the perpetuation and renewal of economic relations, but that it is primarily, in itself, a relationship of force… Power is essentially that which represses.” 
And so we come to the crux of Foucault’s argument (and his difference from Marxism and liberalism) “rather than analyzing it [power] in terms of surrender, contract, and alienation, or rather than analyzing it in functional terms as the reproduction of the relations of production, shouldn’t we be analyzing it first and foremost in terms of conflict, confrontation, and war?
Here he inverts Clausewitz’s aphorism to ask whether ‘politics is the continuation of war by other means’, and continues to state the ideas he will explore through the rest of the book in a nutshell. If politics is the continuation of war by other means, then (my own underlining for emphasis):
This would imply three things. First, that power relations, as they function in a society like ours, are essentially anchored in a certain relationship of force that was established in and through war at a given historical moment that can be historically specified. And while it is true that political power puts an end to war and establishes or attempts to establish the reign of peace in civil society, it certainly does not do so in order to suspend the effects of power or to neutralize the disequilibrium revealed by the last battle of the war. According to this hypothesis, the role of  political power is perpetually to use a sort of silent war to reinscribe that relationship of force, and to reinscribe it in institutions, economic inequalities, language, and even the bodies of individuals. This is the initial meaning of our inversion of Clausewitz’s aphorism-politics is the continuation of war by other means. Politics, in other words, sanctions and reproduces the disequilibrium of forces manifested in war. Inverting the proposition also means something else, namely that within this “civil peace,” these political struggles, these clashes over or with power, these modifications of relations of force-the shifting balance, the reversals-in a political system, all these things must be interpreted as a continuation of war. And they are interpreted as so many episodes, fragmentations, and displacements of the war itself. We are always writing the history of the same war, even when we are writing the history of peace and its institutions.
Inverting Clausewitz’s aphorism also has a third meaning: The final decision can come only from war, or in other words a trial by strength in which weapons are the final judges. It means that the last battle would put an end to politics, or in other words, that the last battle would at last-and I mean “at last”-suspend the exercise of power as continuous warfare. 
That’s a definition and a half, which seems to mean that the achievement of any victory against the status quo requires a battle of strength in which weapons are the final judge. I guess we’re all heading back to the mountains and jungles then, no?
But maybe he jests, because we’re only studying power after all.
The next chapter shows nicely how he turns things upside down. Where the traditional question as he sees it would ask “How does the discourse of truth establish the limits of power’s right?” Foucault would ask “What are the rules of right that power implements to produce discourses of truth? Or: What type of power is it that is capable of producing discourses of power that have, in a society like ours, such powerful effects?” It’s a good illustration, as are the following 5 methodological precautions, which stand as an excellent summary of what Foucault thinks power is, and what power is not (while also making him sound a bit like a Buddhist text). They in turn are summed up thus:
To sum up these five methodological precautions, let me say that rather than orienting our research into power toward the juridical edifice of sovereignty, State apparatuses, and the ideologies that accompany them, I think we should orient our analysis of power toward material operations, forms of subjugation, and the connections among and the uses made of the local systems of subjugation on the one hand, and apparatuses of knowledge on the other. 
This differentiation between state apparatus and material operations is carried through in his discussion of sovereignty and the discourse of rights that emerged in response to it. Foucault suggests that the mechanism of power shifted in the 17th and 18th centuries from essentially feudal monarchy to the kind of power discussed above, while the theorisations of struggle against it did not make the same shift. Whereas power ceased to be about land and goods and legal rights, the critics continued to treat it so while in fact it had become much more about control of time and labour, surveillance, and the mechanics of discipline. Hobbes, for example, in looking at contracts and rights as the foundation for sovereignty completely ignores, and actually hides the fact that power relations have nothing to do with right and everything to do with domination. It is rare you find groups like the Diggers who are able to articulate in some manner that this domination is the problem, rather than Norman lords instead of Saxon lords or what have you.
One of the key sections of the book is of course on race and racism, and a remarkably interesting and unique take on both really that is rich and provocative though I’m not sure what I think about it yet. In a highly simplified form if I understand the argument right: we have long had a concept of sovereignty as legitimate state-based power which words and history existed to praise and exalt to the exclusion (and obfuscation) of all other ideas. Slowly this shifted as a new discourse came into being, a counterhistory of dissent and revolution acknowledging the oppressed and the subjugated. As power and sovereignty was based on the conquest of one people by another (connecting back to Clausewitz’s aphorism though it somehow feels far distant), this took the form of race struggle, a binary struggle of peoples in which everyone was on either one side or the other, their side defining their discourses of truth. In the 16th century what was initially seen as race struggle slowly became seen as class struggle in these counterhistories, and so race began to be used by the counterhistory arising in opposition to the original counterhistories (you can see why this is difficult but this new counterhistory is in the service of those with power). It was reformulated with medical and biological meaning, and as Foucault states: “Whereas the discourse of races, of the struggle between races, was a weapon to be used against the historico-political discourse of Roman sovereignty, the discourse of race (in the singular) was a way of turning that weapon against those who had forged it, of using it to preserve the sovereignty of the State” . Essentially it sought to preserve power and centralise/control discourse through defining the State in terms of its need for protection against the other, the subrace, the enemy. Thus, he argues, racism is only a stage in this larger discourse of race struggle.
He returns to race in the last lecture, which introduces the idea of biopolitics — a term I’ve always found very off-putting but never mind. Essentially it is a new function of government from “sovereignty’s old right — to take life or let live” to “the power to “make” live and “let” die” . It is the State in its new function of measuring and monitoring, nurturing and manipulating the mass of the population for its own benefit rather than simply disciplining individual bodies. This new form of politics does not replace the old, rather it complements and articulates with it in a highly insidious fashion primarily through institutions and specialised scientific knowledges and the development of norms to which individuals and general society must live up to.
Within this new method of governing, racism becomes first, a way to fragment and divide the population for improved control. That’s easy to understand, I’m not sure I fully grasp what follows. In a war situation, it is easy to legitimate that the other ‘people’ must die in order that our ‘people’ may live, thereby giving the state expanded power over life and death. Racism recreates this latitude granted under conditions of war for a regime of biopolitics: “in other words, killing or the imperative to kill is acceptable only if it results not in a victory over political adversaries, but in the elimination of the biological threat to and the improvement of the species or race. There is a direct connection between the two. In a normalizing society, race or racism is the precondition that makes killing acceptable.”  So perhaps that makes sense of this:
And we can also understand why racism should have developed in modern societies that function in the biopower mode; we can understand why racism broke out at a number of privileged moments, and why they were precisely the moments when the right to take life was imperative. Racism first develops with colonization, or in other words, with colonizing genocide. If you are functioning in the biopower mode, how can you justify the need to kill people, to kill populations, and to kill civilizations? By using the themes of evolutionism, by appealing to a racism.
This of course changes war as well, “it is not simply a matter of destroying a political adversary, but of destroying the enemy race”. It makes more sense of Nazism and Stalinism. And I don’t think that it is trying to take the place of other ideas and meanings of race as they lived and experienced, but rather goes deeper adding a new dimension:
here, we are far removed from the ordinary racism that takes the traditional form of mutual contempt or hatred between races. We are also far removed from the racism that can be seen as a sort of ideological operation that allows States, or a class, to displace the hostility that is directed toward [them), or which is tormenting the social body, onto a mythical adversary. I think that this is something much deeper than an old tradition, much deeper than a new ideology, that it is something else. The specificity of modern racism, or what gives it its specificity, is not bound up with mentalities, ideologies, or the lies of power. It is bound up with the technique of power, with the technology of power. It is bound up with this, and that takes us as far away as possible from the race war and the intelligibility of history. We are dealing with a mechanism that allows biopower to work. So racism is bound up with the workings of a State that is obliged to use race, the elimination of races and the purification of the race, to exercise its sovereign power. The juxtaposition of-or the way biopower functions through-the old sovereign power of life and death implies the workings, the introduction and activation, of racism. And it is, I think, here that we find the actual roots of racism. 
It is this much wider more difficult idea of racism that allows Foucault to say “Socialism was a racism from the outset” , contentious words. He argues that because socialism never recognised biopower as a form of control, and the role that racism has played in that, it has essentially recreated (or sought to recreate) these same controls even while changing the social structure. That I can see and is useful in thinking about what happened in Russia, I’m not sure I agree that it is endemic in socialist thought per se in the following way:
Whenever, on the other hand, socialism has been forced to stress the problem of struggle, the struggle against the enemy, of the elimination of the enemy within capitalist society itself, and when, therefore, it has had to think about the physical confrontation with the class enemy in capitalist society, racism does raise its head, because it is the only way in which socialist thought, which is after all very much bound up with the themes of biopower, can rationalize the murder of its enemies. 
There’s so much more here, primarily on the practice and discourses of history, and on the nation. I have to change my rating to 5 stars because while I get so frustrated with Foucault and continue to question the utility of his work to practical struggle, it is undoubtedly full of ideas and questions well worth thinking over, and this is definitely a book I’ll be returning to. I am certain I will find an entirely new set of brilliant/problematic statements to ponder over, which is impressive.