DeLanda: A few years ago you published a critical review of Lee Braver's 2007 book A Thing of This World: A History of Continental Anti-Realism (Harman 2008). As a realist philosopher, you had obvious disagreements with the book, but you also saw it as providing a service to realists because it is a scholarly work, thoroughly researched, and manages to boil down the anti-realist stance to a handful of theses, thereby facilitating a realist appraisal of the problem and an adequate response to it.
Harman: It's a relentless book, refreshingly candid about the anti-realism of mainstream continental thought, especially since (as mentioned earlier) most continental thinkers simply dodge the issue of realism and call it a “pseudo-problem.” The book starts with Kant and runs through numerous key figures, including Hegel, Nietzsche, early and late Heidegger (though I wouldn't differentiate the two periods as much as Braver does), on up to Foucault and Derrida. After surveying Braver's Derrida, it's hard to know where we can go next, since Braver praises him for such a thorough anti-realist conquest that it would be hard to surpass him. And that's the main problem with Braver's book: he sees forward movement in continental philosophy as a fairly straightforward process of progressively washing away a bit more of the original realist sin from one's predecessors, before giving way in turn to younger and more radical anti-realist successors. Naturally, neither you nor I will accept such a procedure.
But though I disagree with the spirit of Braver's narrative – which he has since tried to moderate (Braver 2013) – I love the technical apparatus of the book. This stems from Braver's recognition of the numerous variants of realist and anti-realist doctrines that one might defend. He lists these as six pairs, abbreviated from R1 through R6 for the realist theses and A1 through A6 for the anti-realist ones. They go roughly as follows:
| R1/A1 | The world is not/is dependent on the mind. |
| R2/A2 | Truth is/is not correspondence. |
| R3/A3 | There is/is not one true, complete description of how the world is. |
| R4/A4 | Any statement is/is not necessarily either true or untrue. |
| R5/A5 | Knowledge is/is not passive with respect to what it knows. |
| R6/A6 | The human subject does/does not have a fixed character. |
DeLanda: I completely agree with you that boiling down the history of anti-realism to a few well defined theses provides a valuable service to us, not only clarifying the target of our realist attacks but also summarizing what is wrong with old forms of naive realism. But before we get into that, you also had disagreements with Braver regarding the history of anti-realism itself, especially regarding the position of Heidegger. Braver's shortcoming, you argued, boiled down to neglecting a seventh thesis/antithesis pair:
| R7/A7 | The relation of the human subject with the world is not/is a privileged relation for philosophy. |
Harman: That's right. This occurred to me because of the ambiguous position of Kant with respect to realism. Though Kant is always called a “Transcendental Idealist,” he is nonetheless something of a realist if we take his notion of the thing-in-itself seriously. It not only exists outside the mind, but exists so far outside the mind as to be completely incommensurable with it. Nonetheless, Kant certainly feels like an idealist. Why? I think it's because of a second major aspect of his philosophy: the fact that the thought–world relation is the root of all other relations. In Kant's world we cannot discuss, say, two billiard balls colliding, but only the human experience of two billiard balls colliding, which for him is always mediated by time, space, and the twelve categories of the understanding.
It is quite possible to be an R1 realist about a world outside the mind but simultaneously an A7 anti-realist who sees no possibility of discussing any relation that does not involve human beings. I've already portrayed Kant in this manner, but among more recent philosophers Heidegger is the clear example. He's obviously an A7 thinker for whom Sein and Dasein always come as a pair. Yet I would argue (in the face of considerable opposition) that Heidegger is also an R1 realist for whom Sein is always outside human thought, even if it partially manifests itself only as a correlate of that thought.
The reverse combination is also possible: one can be an A1 anti-realist about an external world but also an R7 realist about the ontological equality of all human and non-human relations. Nietzsche is probably the best example here. He's enough of a perspectivist that it would obviously be hard to call him a naive realist. Yet it's also clear that his “will to power” is a doctrine that applies not just to humans, but to absolutely everything that exists. A stone's or bird's will to power is ontologically equivalent to our own, even if less powerful.
DeLanda: You conclude that given that all the philosophers in this story endorse one or more variants of the six R theses, the only real thread running through all their work is A7, so that their focus is always on the gap between phenomena and noumena, never on the relation between noumena and noumena. I think this is a very important observation, particularly regarding causality. Ontological equality here demands a very specific conception of causes and their effects. For Kant, causality was a conceptual condition of understanding; for Hume, as I said before, it was the observed constant conjunction between two events (e.g., the event “collision between two billiard balls” and the event “change in the ball's state of motion”). For many realists, causality is the objective production of one event by another event; a collision produces changes in the state of motion, whether or not a human being is there to understand it or observe it. While A7 expresses a general asymmetry between relations, I think its importance is particularly clear in the case of relations between causes and their effects. The question of the ontological status of relations also raises important differences between realist and anti-realist positions. These can be incorporated into the discussion if we add another pair of thesis and antithesis:
| R8/A8 | The world is not/is a holistic entity in which everything is inextricably related. |
Deleuze, a rare case of a contemporary continental realist, rejects A8 in the following terms. He distinguishes relations of interiority, in which the very identity of the terms related is constituted by their relation, from relations of exteriority, in which the terms maintain their autonomy despite the fact that their relation may have properties of its own. I would prefer to label this distinction intrinsic/extrinsic, to avoid the confusion of thinking that it refers to something spatial (inside/outside), but we may be stuck with the traditional terms. Now, accepting A8 – that is, accepting that subjects and objects form a seamless totality – clearly plays an important role in anti-realism. In your review you mention a few cases of this: Heidegger's transformation of R1's mind-independence into mutual interdependence, so that being and man exist only in relation to one another, hence sustaining A7.
In this respect I am a bit confused with your use of the word “relationism” as something that implies anti-realism. This would be true if we accept intrinsic relations that determine the very identity of what they relate, but not if we only accept extrinsic relations. So we should be careful when using the words “relational” and “non-relational” without specifying whether the relations are extrinsic or intrinsic.
Harman: When I speak of “relationism” I'm referring to any philosophy that takes the relations of an entity to be intrinsic to its constitution. One example is Whitehead (1978), who says that to understand any actual entity we must analyze it into its prehensions (relations). Another is Latour (1999: 122), who says that an actor is nothing more than whatever it transforms, modifies, perturbs, or creates. Still another is Barad, who says that relata do not precede their relations. These are all extreme ontological positions, and untenable ones even if all have their merits as well. What invariably happens is that people claim I'm exaggerating these positions; after all, Whitehead, Latour, and Barad can't be stupid enough to be as one-sided as I claim. But this objection confuses philosophers with their philosophies; it's not a question of whether Whitehead found it necessary to escape the consequences of full-blown relationism (as with his concept of “subjective aim”). The question is not whether Whitehead, Latour, or Barad tried to do the job of balancing everything (every philosopher claims to have achieved a balanced synthesis of all possible extreme positions), but of whether they succeeded. And I'm sure you agree that these forms of relationism cannot succeed. As for extrinsic relations, of course they occur, but for me they don't belong to the relata. Instead, they belong to the relation considered as a new object.
DeLanda: To be honest I am not as familiar as you are with Whitehead's work, but in the case of Latour the idea that science, technology, and society form a seamless totality seems to be crucial to his anti-realist methodology. But I would want to add one more pair of thesis and antithesis:
| R9/A9 | Subjective experience is not/is linguistically structured. |
In your review of Braver, you noted that in the latest round of purging realist content (the reality of historical conceptual frameworks) Derrida's move was to deny that any referent exists outside the text because our experience is linguistically mediated. This is clearly an endorsement of A9. More generally, if one believes that language segments a continuous lived experience assigning meaning to each segment, then given the acknowledged fact that the link between language and the world is arbitrary and varies from culture to culture, it follows that each culture lives in its own world, and that there is not one real world that we all share. My views on this are as follows.
Conscious experience must indeed be meaningful to a subject. But the word “meaningful” has two different senses, exemplified by the phrases “a meaningful statement” and “a meaningful life.” In the first case we are dealing with signification (semantic content) in the second with significance (relevance, importance). Something without signification is nonsensical; something without significance is trivial. I believe that subjective experience, even that of non-human animals, must posses significance: the importance of the opportunities and risks afforded by the environment must be grasped by the animal; what makes a difference to it must be highlighted into a figure, while the rest must be relegated to the background as being insignificant. Thus, animal experience is meaningful not because it possesses signification, but because of the significance (or lack thereof) of its contents. What's your take on this?
Harman: The distinction between significance and signification seems like a good one, as does the R9/A9 pair. On a related note, as time goes by I see Derrida as more of a Husserlian than a Heideggerian. It's true that for Heidegger the A7 Sein/Dasein relationship is at the center of philosophy, with no role for object–object relations at all. Yet there's also as much R1 mind-independent reality in Heidegger as there is in Kant. Being for Heidegger is that which always withdraws from representation; unlike for Husserl, who calls it an absurdity to think of a thing-in-itself that would not at least potentially be the correlate of some mental act. Enter Derrida, who in Of Grammatology makes some really misleading claims about Heidegger, such as saying that for Heidegger there is no Being outside its specific historical manifestations to humans (Derrida 2016: 22). This is merely Derrida's own wish, not part of Heidegger's philosophy. In his contempt for the in-itself, Derrida is a lot closer to Husserlian phenomenology than to Heidegger.
DeLanda: When Husserl thinks it absurd to think of noumena outside their relation to humans, is this not simply a manifestation of his allegiance to A8? If the relation between knowing subject and known object is one of interiority, if both subject and object are constituted by their relation, then it follows that they are fused into a seamless whole of which only “aspects” can be discerned. If this is correct, then A8 is at the heart of anti-realism, forcing philosophers to conflate ontological and epistemological questions. Endorsing R8, on the other hand, allows us to keep subject and object separable, although we still need to account for the capacity of the subject to know and the capacity of the object to be known.
Harman: It's certainly true that Husserl makes the object dependent on consciousness in a way that Heidegger does not, and in that sense he gives us an intrinsic relation between knowing subject and known object. Even so, I'd be more inclined to label Husserl (who is strangely absent from Braver's book) as an R8 anti-holist but an A1 mind-dependent anti-realist. The reason I'd prefer not to call him a holist is that this would imply (beyond subject/object interdependence) that all of his phenomena are somehow interwoven with each other no less than with the mind, as we find in the structuralists and even in Derrida.
But Husserl's idealism is a strange one, in the sense that his objects (which are always intentional objects, never real ones) are deeper than any context in which they happen to appear. The essence of each phenomenon is radically non-contextual, since it can inhabit numerous different contexts and still be the same phenomenal object. It's true that we always see a mailbox from a specific angle and distance, in a specific mood, at a specific time of day, and in a specific relation to other objects. But the surprising thing is that for Husserl the mailbox has no intrinsic relations, other than the fact that it must be related to a mind. The whole point of phenomenological analysis, after all, is to strip away the accidental “adumbrations“ through eidetic variation until we reach the genuine eidos of the phenomenon. Unlike Derrida, Husserl draws a clean separation between the essence and the accidents of an object. It would make Husserl sound a lot like Aristotle, if not that Husserl is a radical idealist.
DeLanda: I take the existence of appearances seriously; subjectively experienced color, for example, is a different entity from the objective properties of light (wavelength); of the pigmented surfaces that reflect light (reflectance); and of the medium through which light travels. These objective properties do contribute to the experience (an object at a distance does appear bluer because of the effect of the intervening air) but color is not reducible to them. Now, philosophers use the word “introspection” for the activity involved in the exploration of appearances, a kind of spotlight that is directed inwards to shine light on our inner mental life. (Hence the idea of qualia as private and ineffable.) I understand the use of the word “introspection” when digging within yourself to find out whether, for example, your avowed motives for performing an action are indeed what you think they are. Unlike this case, however, the study of appearances involves not looking inwards but outwards, while making a special use of attention. Rather than go beyond appearances to the objects that appear (as most people do), we direct our attention to appearances themselves. When I look at a rectangular table as I walk around it, its shape appears to me as a changing trapezoid (due to perspective), but most of the time I do not see a trapezoid, but a rectangle (as our brain extracts this invariant form from the variable shapes projecting into my retina).
Can you explain to me what Husserl's method of bracketing is supposed to be? Intuitively, the idea seems to be that the method allows you to evacuate all the objective (in his terms, transcendent) content of consciousness, and leaving only the (in his terms) immanent content, that is, what does not go beyond the world as it is given to a subject. To me, this seems to refer to appearances: the trapezoidal shape of the table, not its real rectangular shape, since the latter does assume that you go beyond what is directly given.
Harman: It certainly requires that we be aware that the table currently appears as a trapezoid rather than a rectangle, but this is just one “adumbration” of the table as an object, which has numerous different possible shapes depending on where we view it from, and is not bound up with any particular sensual shape. Adumbrations are known by the senses, but the eidos of any given intentional object can be known only by the intellect, not by the senses. But indeed, the basic idea of bracketing is to focus exclusively on immanent content rather than any question of external existence, since Husserl thinks it is flat-out absurd to conceive of a reality that could not be immanent in consciousness at least in principle. I say “in principle” because he doesn't think everything needs to be actively looked at in this moment to exist, à la Berkeley. Nonetheless, there are two kinds of content for Husserl. First, there are the perceptual adumbrations (the apple or coffee cup or trapezoidal table as we see it in this very moment), which are accidental and can vary within a wide range without the object itself changing its identity. This is where Husserl abandons Hume's “bundle of qualities” theory of perceptual experience that is openly or tacitly retained all the way through Brentano (1995), who wrongly assumes that presentation is the root of all intentionality. Husserl is right to reject this assumption of his teacher, because objects are given as independent of any of their easily modifiable presentations. The blackbird in the garden is the same blackbird no matter what angle or distance it is presented from.
Husserl is indeed a purely immanent thinker, but within this immanence we have to distinguish between the immanent object and its swirling adumbrations that are accidental and largely in flux. It's true, as you say, that Husserl would first ask us to forget our everyday preconceptions about a square table and pay close attention to its trapezoidal adumbrations. But the trapezoidal shapes exist only as viewpoints on the immanent table-object, made up of the essential features of the table. So while Husserl remains within immanence, he tries to move from immanent sensation (the trapezoids are definitely there) to immanent intellection (which would have to refuse the trapezoids, since these belong to the kingdom of the senses).
DeLanda: As I will explain below, when we return to questions about lived experience, I account for the transformation of changing adumbrations into a lived object (that is more than a bundle of properties) by mechanisms through which the brain extracts invariants from appearances: the rectangular shape “beneath” all the trapezoidal presentations, for example. And similarly for color: if the red table in front of me is only partly lit by the sun, the adumbration is of a surface (the top of the table) with two different colors (dark and light red). But the sensual object is not lived as having two colors but as having just one color while being illuminated differently in different portions: one invariant color “beneath” the lighting effect. But we should postpone this topic for later and return to the set of ontological theses with which we began this chapter to state how contemporary realists should respond to each one of them in turn. For ease of reference let's present the original list again, together with the extra theses we appended to it:
| R1/A1 | The world is not/is dependent on the mind. |
| R2/A2 | Truth is/is not correspondence. |
| R3/A3 | There is/is not one true, complete description of how the world is. |
| R4/A4 | Any statement is/is not necessarily either true or untrue. |
| R5/A5 | Knowledge is/is not passive with respect to what it knows. |
| R6/A6 | The human subject does/does not have a fixed character. |
| R7/A7 | The relation of the human subject with the world is not/is a privileged relation for philosophy. |
| R8/A8 | The world is not/is a holistic entity in which everything is inextricably related. |
| R9/A9 | Subjective experience is not/is linguistically structured. |
Let's start with R1 and specify what we understand by a mind-independent world. I usually start this discussion by first establishing the plausibility of the notion, without pretending to be giving a compelling proof. This can be achieved by accepting a single thesis: the historicity of the human species. Now, although Darwin is prominent among those scientists who defended this thesis, the thesis can be upheld without having to take a stance on the many debates and unsettled questions in Darwinism, such as whether natural selection is enough to “sculpt” the bodies of plants and animals, or whether we also need self-organizing embryological processes to generate their form. We can be agnostic about all this and simply accept that there was a time (say, six million years ago) when there were no human beings on the planet, and yet the latter already revolved around the sun, it had a climate and a geology, and was inhabited by plants and animals. This gives us a minimal conception of mind-independent entities which is plausible and, at least in principle, a posteriori, since its plausibility depends on the existence of evidence, like the fossils of now extinct animals and plants. How would you defend R1?
Harman: My own defense of R1 passes through ontological rather than scientific principles. I must be one of the few people who became a realist while trying to make sense of Heidegger, most of whose commentators treat him as a pragmatist if not an outright idealist. It's easy to see why this happens. Heidegger's tool-analysis seems to argue that praxis comes before theory, and that all tools are woven into a holistic system whose meaning is determined by human being, or Dasein. And yet, praxis comes up short of the things in the world no less than theory does: to use a hammer does not exhaust it any more than perceiving or theorizing about it does. There's a surplus in the hammer, and none of our relations to the hammer does that surplus justice. And furthermore, the tool-system cannot be holistic, because Heidegger is also the thinker of broken tools, and the only reason they can break is because “tools” (namely, all beings) are not fully deployed in their current references to one another.
I have no real problem with your argument from plausibility, by the way. It may be difficult to prove the existence of a world without humans against the radical doubt of a Descartes or even more radical certainty of a Berkeley, but I'm with Whitehead when he says that philosophies are abandoned, not refuted. (Whitehead 1978: 6). We don't reject a philosophy because it's missing a “knockdown argument” or an unshakeable first principle, but because it seems unable to account for large swathes of experience. The great likelihood that the universe pre-existed humans has enough prima facie plausibility that any philosophy denying it has a heavy burden to carry. Nonetheless, it wasn't my lifelong interest in science that made me a realist, since as a student I took the idealist arguments of Fichte and Husserl very seriously. It was only Heidegger's withdrawn tool-beings that made me a realist, even though Heidegger never goes far enough down the realist path himself.
DeLanda: I also think that the argument from plausibility must be reinforced by ontological arguments. In particular, as a contemporary analytical realist (Ian Hacking) argues, we get stronger reassurance of the reality of entities from mastering their capacities to affect and be affected than from a theoretical description of their properties (Hacking 1983). He gives the example of electrons. Why should we believe they exist independently of our minds? Because of our theoretical knowledge of them? Not really, since the latter has changed often: electrons were first conceived as particles then as waves. Rather, it is the practical mastery of their capacities that reassures us. Take Hacking's example of CRT's (the cathode ray tubes that were everyone's monitors and television sets prior to the flat screen age.) A CRT consists of an electron emitter and a fluorescent surface acting as a screen. Images are produced by deflecting the electron beam electrostatically or magnetically. There can be little argument that CRTs have greatly improved by their own standard: the quality of the image produced on the screen. But they have become better imaging devices thanks to our greater understanding of the capacities of electrons to affect the phosphor-coated surfaces on which they are sprayed, as well as their capacity to be affected by electric or magnetic fields. This line of argument is more about technology (that is, tools) than science. Although there are many species that use tools (crows, chimps, even insects) we humans certainly excel at inventing new ones. But to conceive of tools as autonomous we need to redefine mind-independence, because tools would not exist if human minds did not exist. Hence, in the case of social entities (from tools to cities), the expression should signify independence from the content of our minds, not from their existence.
Harman: I heartily agree that mind-independence entails independence from the content of our minds, not from the existence of our minds. You made this point brilliantly on the first page of A New Philosophy of Society (2006: 1), which I have cited many times because there is frequent confusion between the two senses of “mind-independence.” For example, since Speculative Realism is supposed to be about the world independent of humans, people assume that we want to talk about a world without humans. Thus I am sometimes asked questions such as “What would an art without humans look like?” But we don't need to talk about art in a post-apocalyptic world where humans are extinct; we only need to talk about art as not being exhausted by any particular human interpretation of it. Even as great an art critic as Michael Fried, in his classic 1967 essay “Art and Objecthood,” conflates humans as observers with what I would call humans as ingredients (Fried 1998). You've done the best job known to me of drawing the right distinction between these two very different senses of mind-independence.
DeLanda: Moving on to R2: truth as correspondence to reality. My stance here can be summarized in two related statements. First, I believe that the concept of truth is coherent only when applied to individual statements, not whole theories. The problematic mirror-like relation that anti-realists emphasize arises only for entire theories (e.g., exhaustive descriptions) not statements. Truth for the latter can be reduced to reference and predication, and both can be accounted for without using the idea of a reflection of reality. Reference, for example, can be established by causal interventions: this chunk of yellow metal is the referent of the word “gold” if it dissolves when we pour a certain acid on it, as assayers since ancient times have done. Second, any body of knowledge consists of more than just true statements; it possesses problems, explanations, classifications, and other cognitive tools each of which has its own conditions of rightness of fit. Problems can be well or badly posed; explanations adequate or inadequate; taxonomies partial and arbitrary or comprehensive and justified. The expression “rightness of fit” comes from Nelson Goodman (1978), an empiricist who rejected only the naive realism implied by the unmodified versions of R1–R6. Thus, the idea of correspondence is not only unnecessary when dealing with single statements, it is incomplete as an account of the relation between the cognitive content of science and the world.
Harman: There are several problems with truth as correspondence. First, I think it's important to be a fallibilist given the repeated abandonment of once-cherished scientific theories. The analytic philosopher Paul Boghossian, in his widely read book Fear of Knowledge (2006), defines knowledge in a familiar way as “justified true belief” (Harman 2015). The problem is that we can only know at any given moment what is justified by available evidence, not what is really true. Boghossian calls himself a fallibilist, so he ought to realize this. What it means is that we never really attain knowledge in the sense of correspondence. Let's assume for the sake of argument that we had a final, perfectly adequate theory of some entity – say, fire. Even this perfect knowledge of fire would not burn, would not be hot, would not flicker, and so forth. Now, some might say that this is a “straw man” argument, since no one other than Berkeley has really argued otherwise. But the point is not whether anyone openly argues for the identity of real fire and mental fire. The point is that the notion of truth as correspondence entails this identity unless the difference between the two can be specified.
DeLanda: Well, from my previous remarks (reference as fixed by causal interventions) you can imagine that this problem (the identity of real and perceived fire) does not even arise for me: real fire has causal powers (e.g., the power of burning) that perceived fire does not. But the distinction between truth for individual statements and truth for entire theories connects with the next thesis: the existence of a complete description of the world, or R3. At first this would seem to be an epistemological thesis (about our capacities to fully understand reality) but it sneaks an ontological thesis through the back door: that the world as it is now has a fixed and finished nature. Now, if you are a physicist dealing with four kinds of forces (gravity, electromagnetism, and the two atomic forces) you can dream about a “theory of everything” because, after all, how hard can it be to explain four entities? But to a chemist who is constantly synthesizing substances that do not exist in nature, that goal would seem elusive (DeLanda 2015). One philosopher of chemistry calculates that chemists introduce one million novel substances every year into their domain. Studying the chemical reactions in which these substances display their causal powers is literally impossible. Thus, the goal of producing a complete description (let alone explanation) of the chemical domain recedes further into the horizon as time goes by. No chemist could possibly dream of a final theory.
This argument can be made independent of the contingencies of any one scientific field. If an objective whole is characterized by its properties and the latter are conceived as emergent (as produced by the continuous interaction of the whole's parts) then we add another way in which reality is open-ended: any given emergent whole can become a component part of a larger whole with new properties of its own. Because the emergence relation is recursive, it can yield a sequence of entities that need not have an end: atoms compose an indefinite number of molecules, molecules an indefinite number of living cells, cells an indefinite number of organisms, and so on.
Harman: I'm certainly with you on emergence, and as an argument against R3 the continual emergence of new objects to be studied is a good one. But let's say an R3 realist were to respond by saying: “I didn't mean that new entities can never be produced. I just meant that it's possible to give a true, complete description of the world as it is right now.” If formulated this way, then the weight of R3 seems to lean toward a claim about the commensurability of realities and their descriptions. I don't like this idea at all, because it assumes that everything in the world can be translated into a literal, propositional statement without losing anything. But literary critics have known for decades that this is untrue of metaphors and even of entire poems: there is no good literal way to explain what a poem means (Brooks 1947). Jokes are ruined if explained in detailed prose terms. Threats and erotic language lose a great deal if replaced by literal propositions. The same for artworks. Yet people want literal scientific descriptions to be the gold standard of truth. Now, we can ask, what is a literal statement? And I think a good definition would be this: “A literal statement converts proper names into lists of true attributes.” Instead of just saying “electron,” science discovers all the electron's properties. It's like Russell's position as contrasted with Kripke's (Russell 1905; Kripke 1996) So I find myself rejecting R3 because I don't think the world can be paraphrased into any number of literal statements. The things in the world are not bundles of qualities as Hume (1978) thought, and therefore cannot be converted into bundles of accurate descriptions. Thus, language can never be purged of its allusive and elliptical character.
DeLanda: The obsession with language and logic is also behind the next pair, R4/A4, which is basically an affirmation (or denial) of the logical principle of the excluded middle. I never understood the importance of this principle other than to allow for logical proofs via reductio ad absurdum: instead of offering a constructive proof that a statement is true, one simply shows that the negation of the statement leads to a contradiction. (The intuitionist school of math rejected R4 precisely because of this.) R4 also allows us to create analytic a priori truths, like “either all men are mortal or they are not.” Once you reject a priori truths (even synthetic ones) there is no need to lose much sleep over R4. The kinds of logics that can be created (like the kinds of molecules or organisms) are open-ended. In particular, so-called fuzzy logics exist that allow for continuous values between true and false, and they have proved invaluable in practical applications in which properties like temperature or chemical concentration vary continuously. Finally, I must add that (with one exception) the logical calculi that have been invented so far do not contain the resources needed to model significant truths. But most truths are trivial; I can produce one hundred truths in the next minute by describing the outfit I am wearing, none of which would have any philosophical relevance. Hence, without adding the notion of significance, logic alone tends to generate badly posed philosophical problems, like the anti-realist Quine/Duhem problem of the underdetermination of theoretical statements by observational evidence (Quine 1980; Duhem 1991). Hence, rejecting (or being indifferent to) R4, does not imply subscribing to A4 as providing support for anti-realism.
Harman: In general, I'm not very sympathetic to definitions of realism that invoke statements like R4. The existence of mind-independent realities is one question, but our ability to know or say things about those realities is quite another. People too often assume that the existence of things outside the mind immediately entails our ability to know those things directly and adequately. Behind this assumption there often lurks a naive form of science-worship, as if the main benefit of reality were that it allows us to police and punish the irrationality of others. R4/A4 is another topic where Whitehead is especially helpful. He notes that if we apply the question “True or false?” to any given philosophy, the answer has to be “false.” That's because any statement is necessarily an abstraction from a far more intricate situation. You mentioned fuzzy logic, and enthusiasts of Eastern philosophy often cite Nagarjuna in this context, since for him statements can also be both true and false, or neither true nor false (Tola & Dragonetti 2004). And now I see that we're coming to R5/A5, and the question of whether knowledge is passive.
DeLanda: The problem with R5/A5 is that I cannot think of a realist philosopher today who would not accept A5. So the important question, as far as ontological commitments go, is whether one believes in the conjunction A5/A9 or A5/R9. The first couple tends to lead thinkers to anti-realist positions, whereas the second meshes well with realism. Let me spell this out. Those who subscribe to the first couple conceive of the activity of the knowing subject as being basically classificatory: knowledge (or understanding) consists in bringing percepts under a general category, whether this is conceived as something common to all humanity (time, space, causality) or something entirely conventional that varies from culture to culture. It is only the latter position that unambiguously signals anti-realist commitments. The former position (Kant's original position) can be given an evolutionary explanation: humans can only see small portions of our round planet, portions that appear flat for all practical purposes, so we can imagine that evolution led to the development of neural machinery to facilitate the processing of Euclidean geometry. (And similarly for time and causality.) Coupling A5 to R9, on the other hand, leads us to conceive of the activity of the knowing subject as involving not classification but explanation. The latter depends on active assessments of significance, that is, on discovering which factors make (or do not make) a difference to the outcome of a process. In addition, when realists conceive of the human subject as embodied (as opposed to a disembodied observer), another source of active participation in the production of knowledge is the causal intervention that a body makes possible. Classification may be able to tell us about an object's properties, but not about its capacities if the latter are not currently being exercised. Hence, we need to explore the world, force things to interact with one another so that their capacities are revealed as they affect and are affected by one another.
Harman: Braver's point here was that analytic philosophy was launched by Moore and Russell as an R5 position designed to reverse Kant's notion of the mind having an active role in how we experience the world. Russell's theory of descriptions, in particular, which was meant to give a drastic haircut to Meinong's inflationary universe, was also a perfect model of so-called naive realism, meaning that there is no problem with the human mind gaining access to the real (Russell 1905; Meinong 1983). Whether any major analytic philosophers today would enlist under R5, I don't know. On the continental side I don't think even Meillassoux's mathematicist ontology is an R5 position, since he starts by affirming the correlationist claim that we can't think the unthought without turning it into a thought. Of course I agree with your point that active intervention is needed to discover the currently unexercised capacities of things. As for Kant's original position, my only serious objection is to his A7 assumption that the human–world interaction is ontologically different from object–object interactions in the world. There is something extrinsic about every relation between things, and that's why I don't think the Ding an sich should have been framed as a tragic burden of finitude shouldered by humans alone. German Idealism moved beyond Kant by flipping the R1 thing-in-itself into an A1 position in which the noumenon is just a special case of the phenomenon. I wish instead that someone had kept the R1 Kant but flipped his A7 into an R7 position. We would then have had a German Realism (not implausible, due to Leibniz's continued strong influence in Germany at the time) in which relations fail to exhaust their relata whether humans are involved or not. For me it's one of the great counterfactual crossroads in the history of Western philosophy: the road from Kant to Hegel was not a necessary one.
DeLanda: The main form of R7 that I endorse is the symmetry between the causal interactions between subject and object and those between objects with each other. In both cases we are talking about an objective relation of production between events, and those causal relations in which humans are involved are not privileged in any way relative to those involving only non-human agents.
Harman: It's true that both Hume and Kant define causation in terms of how it is observed rather than how it is produced, and this has been the biggest obstacle to R7 in recent philosophy. Hume and Kant are in many ways the beginning of contemporary philosophy, in the sense that one can literally be a Humean or Kantian and still be taken seriously in Western academia. That's not true for most earlier figures: Descartes, Spinoza, Leibniz, and Berkeley have their admirers, but no one literally believes all that they say on an issue-by-issue basis. But I also see Hume and Kant as an extension of the occasionalist tradition. Occasionalism, which actually started in medieval Iraq nearly a millennium before it first sprouted in seventeenth-century Europe, is the view that God is the only causal mediator; two things cannot affect each other without passing through God. It's almost impossible to find someone in the secularized West who will go that far, yet occasionalism lives on through Hume and Kant. How so? The real problem with occasionalism was not that God was the sole causal mediator, but that any one entity was given a causal monopoly. And that's precisely what Hume and Kant are doing, simply transferring the causal monopoly from God to the human mind. And unlike the religious occasionalists, they have succeeded in persuading modern Western intellectuals.
But let's move on to Braver's R6/A6, the question of whether the human mind has (R6) or does not have (A6) a fixed character. First off, I'm not sure I would even assign the R and A terms in this way. Surely it is more of an idealist move to assert that the human mind has a fixed character that formats the world we experience, and more of a realist move to say that the human mind is in the world just like everything else, and therefore that the mind can alter through evolution, accidental brain damage, psychosis, and so forth. In any case, I see no reason why a realist would need to subscribe to a fixed character of the human mind.
DeLanda: I also believe that the fixity of human subjectivity is more of a problem for idealists, since they make subjective phenomena the sole focus of philosophical research. Nevertheless, realists must also have an account of subjectivity given that appearances (and their invariants) are genuine inhabitants of this world. We will be dealing with this issue later, when we return to questions about phenomenal experience, but for now I would want to add that just as the enduring identity of an object must be accounted for by mechanisms of emergence (both the processes in the past that gave birth to the object, as well as those in the present that maintain that identity), so too does the identity of a subject. In the case of subjectivity, Deleuze's (1991) reading of Hume gives us a clue: habit (habitual or routine activity) plays a stabilizing role in the case of subjectivity. But Hume considered only habits, whereas I would also add skills. Both habits and skills imply an embodied subject, but skills (what Gilbert Ryle called “knowing how,” opposing it to representational knowledge or “knowing that”) expand subjectivity rather than fix it (Ryle 1949). When one first learns how to swim or how to ride a bike, entirely new spaces (the ocean, or places away from the familiarity of home) open up, and the world of subjective phenomena becomes richer. So I agree that mental disease, alcohol and drugs, brain damage, and so on all provide evidence for the possibility of destabilizing subjectivity, but mastery of novel skills shows that this destabilization can also be constructive, enhancing or enriching subjective identity.