Part 13 (2/2)

The first surprise is that it takes constraints on the release of energy to perform work, but it takes work to create constraints. The second surprise is that constraints are information and information is constraint.

-STUART KAUFFMAN, PERSONAL COMMUNICATION.

ABOUTNESS MATTERS.

As we have seen, nearly every physical interaction in the universe can be described in terms of Shannon information, and any relations.h.i.+p involving physical malleability, whether exemplified or not, can be interpreted as information about something else. This has led some writers to suggest that the universe is made of information, not matter. But this tells us little more than that the universe is a manifold of physical differences and that most are the result of prior work. Of course, not every physical difference is interpreted, or even can be interpreted, though all may at some point contribute to future physical changes. Interpretation is ultimately a physical process, but one with a quite distinctive kind of causal organization. So, although almost every physical difference in the history of the universe can potentially be interpreted to provide information about any number of other linked physical occurrences, the unimaginably vast majority of these go uninterpreted, and so cannot be said to be information about anything. Without interpretation, a physical difference is just a physical difference, and calling these ubiquitous differences ”information” furthermore runs the risk of collapsing the distinction between information, matter, and energy, and ultimately eliminating the entire realm of ententional phenomena from consideration.

Although any physical difference can become significant and provide information about something else, interpretation requires that certain very restricted forms of physical processes must be produced. The organization of these processes distinguishes interpretation from mere physical cause and effect. Consider again Gregory Bateson's aphorism: ”a difference that makes a difference.” Its meaning turns on the ambiguity between two senses of to ”make a difference.” The more literal meaning is to cause something to change from what otherwise would have occurred. This is effectively a claim about performing work (in any of the senses that we have described). In idiomatic English, however, it also means to be of value (either positive or negative) to some recipient or to serve some purpose. I interpret Bateson's point to be that both meanings are relevant. Taken together, then, these two meanings describe work that is initiated in order to effect a change that will serve some end. Some favored consequence must be promoted, or some unwanted consequence must be impeded, by the work that has been performed in response to the property of the sign medium that is taken as information.

This is why an interpretive process is more than a mere causal process. It organizes work in response to the state of a sign medium and with respect to some normative consequence-a general type of consequence that is in some way valued over others. This characterization of creating/making a difference in both senses suggests that the sort of work that Bateson has in mind is not merely thermodynamic work. To ”make a difference” in the normative sense of this phrase is (in the terms we have developed) to support some teleodynamic process. It must contribute to the potential to initiate, support, or inhibit teleodynamic work, because only teleodynamic processes can have normative consequences. So to explain the basis of an interpretation process is to trace the way that teleodynamic work transforms mere physical work into semiotic relations.h.i.+ps, and back again.

As our dynamical a.n.a.lysis has shown, teleodynamic work emerges from and depends on both morphodynamic and thermodynamic work. Consequently, these lower forms of work must also be involved in any process of interpretation. If this is the case, then an interpreting process must depend on extrinsic energetic and material resources and must also involve far-from-equilibrium self-organizing processes. In this roundabout way, like the dynamical processes that characterize organisms, the interpretation of something as information involves a form of recursive organization whereby the interpretation of something as information indirectly reinforces the capacity to do this again.

BEYOND CYBERNETICS.

Perhaps the first hint that the 2,000-year-old mystery of interpretation might be susceptible to a physical explanation rather than remaining forever metaphysical can be attributed to the development of a formal theory of regulation and control, which can rightfully be said to have initiated the information age. This major step forward in defining the relations.h.i.+p between information and its physical consequences was provided by the development of cybernetic theory in the 1950s and 60s. The term cybernetic was coined by its most important theoretician, Norbert Wiener, and comes from the same Greek root as the word ”government,” referring to steering or controlling. Within cybernetic theory, for the first time it became possible to specify how information (in the Shannonian sense) could have definite physical consequences and could contribute to the attractor dynamics const.i.tuting teleonomic behaviors.

In chapter 4, we were introduced to the concept of teleonomic behavior and the simple mechanistic exemplar of negative feedback regulation: thermostatic control circuit. This model system not only demonstrates the fundamental principles of this paradigm, and the way it conceives of the linkage between information as a physical difference and a potential physical consequence; it also provides a critical clue to its own inadequacy.

A thermostat regulates the temperature in a room by virtue of the way that a switch controlling a heating device is turned on or off by the effects of that temperature. The way these changes correlate with the state of the switch and the functioning of the heating device creates a deviation-minimizing pattern of behavior. It's a process whereby one difference sets in motion a chain of difference-making processes that ultimately ”make a difference” in keeping conditions within a desired range for some purpose. Thus a difference in the surrounding temperature produces a difference in the state of the switch, which produces a difference in the operation of the heater, which produces a difference in the temperature of the room, which produces a difference in the state of the switch, and so forth. At each stage, work is done on a later component in the circuit with respect to a change in some feature of the previous component, resulting in a circularity of causal influences. Thus it is often argued that each subsequent step along the chain of events in this cycle ”interprets” the information provided by the previous step, and that information is being pa.s.sed around this causal circuit. But in what sense do these terms apply? Are they merely metaphoric?

We can dissect this problem by dissecting the circuit itself. A cla.s.sic mechanical-electrical thermostat design involves a mercury switch attached to a coiled bimetallic strip, which expands when warmed, thus tipping the switch one way, and contracts when cooled, tipping the switch the other way (cf. Figure 4.1). The angle of the switch determines whether the circuit is completed or interrupted. But let's consider one of these steps in isolation. Is the coiling and uncoiling of a bimetallic strip information about temperature? It certainly could be used as such to an observer who understood this relations.h.i.+p and was bringing this knowledge to bear in considering the relations.h.i.+p. But what if this change of states goes unnoticed? Physically, there is no difference. The change in state of the coiled strip and of the room temperature will occur irrespective of ether being observed. Like the wax impression of a signet ring, it is merely a physical phenomenon that could be interpreted as information about something in particular. Of course, it could also be interpreted as information about many other things. For example, its behavior could be interpreted to be information about the differential responsiveness of the two metals. Or it could be mistakenly interpreted as magic or some intrinsic tendency to grow and shrink at random. Is being incorporated into a thermostatic circuit sufficient to justify describing the coiling behavior as ”information” about temperature to the circuit? Or is this too still only one of many possible things it could provide information about? What makes it information about anything rather than just a simple physical influence? Clearly, it is the process of interpretation that matters, not merely this physical tendency, and that is an entirely separate causal process.

Consider, in contrast, a single-cell organism responding to a change in temperature by changing its chemical metabolism. Additionally, a.s.sume that some molecular process within the organism, which is the equivalent of a simple thermostatic device, accomplishes this change. In many respects, it is more like a thermostat installed by a human user to maintain room temperature than a feedback process that might occur spontaneously in inorganic nature. This is because both the molecular regulator of the cell and the engineered thermostat embody constraints that are useful to some superordinate system for which they are at the same time both supportive and supported components. In a thermostat, it is the desired attractor dynamics (desired by its human users), and not any one specific material or energetic configuration, that determines its design. In organisms, such convergent behaviors were likely to have been favored by natural selection to buffer any undesirable changes of internal temperature. Indeed, in both living and engineered regulators, there can be many different ways that a given attractor dynamics is achieved. Moreover, a.n.a.logously functioning living mechanisms often arise via parallel or convergent evolution from quite different precursors.

This drives home the point that it is this pattern of behavior that determines the existence of both the evolved and engineered regulatory systems, not the sharing of any similar material const.i.tution or a common accidental origin. In contrast, Old Faithful was formed by a singular geological accident, and the regularity of its deviation-minimizing hydrothermal behavior had nothing to do with its initial formation. Nor does its feedback logic play any significant role in how long this behavior will persist. If the geology changes or the source of water is depleted, the process will simply cease.

We are thus warranted in using the term information to describe the physical changes that get propagated from component to component in a designed or evolved feedback circuit only because the resultant attractor dynamics itself played the determinate role in generating the architecture of this mechanism. In such cases, we also recognize that its physical composition and component dynamical operations are replaceable so long as this attractor-governed behavior is reliably achieved. In contrast, it is also why, in the case of Old Faithful or any other accidentally occurring non-living feedback process, it feels strange to use information terminology to describe their dynamics, except in a metaphoric or merely Shannonian sense. Although they too may exhibit a tendency to converge-toward or resist-deviation-away-from a specific attractor state, the causal histories and future persistence of these processes lack this crucial attribute. Indeed, a designed or evolved feedback mechanism and an accidentally occurring a.n.a.logue might even be mechanistically identical, and we still would need to make this distinction.

WORKING IT OUT.

As Shannon's a.n.a.lysis showed, information is embodied in constraints, and, as we have additionally shown, what these constraints can be about is a function of the work that ultimately was responsible for producing them (or could have produced them, even if they are never generated), either directly or indirectly. But as Stuart Kauffman points out in the epigraph at the beginning of this chapter, not only does it take work to produce constraints, it takes constraints to produce work. So one way in which the referential content of information can indirectly influence the physical world is if the constraints embodied in the informing medium can become the basis for specifying further work. And differences of constraint can determine differences in effect.

This capacity for one form of work to produce the constraints that organize another, independent form of work is the source of the amplifying power of information. It affords a means to couple otherwise unrelated contragrade processes into highly complex and indirect chains. And because of the complementary roles of constraint and energy-gradient reduction, it also provides the means for using the depletion of a small energy gradient to create constraints that are able to organize the depletion of a much larger energy gradient. In this way, information can serve as the bridge linking the properties of otherwise quite separate and unrelated material and energetic systems. As a result, chains of otherwise non-interacting contragrade processes can be linked. Work done with the aid of one energy gradient can generate constraints in a signaling medium, which can in turn be used to channel work utilizing another quite different energy gradient to create constraints in yet some other medium, and so forth. By repeating such transfers step by step from medium to medium, process to process, causal linkages between phenomena that otherwise would be astronomically unlikely to occur spontaneously can be brought into existence. This is why information, whether embodied in biological processes, engineered devices, or theoretical speculations, has so radically altered the causal fabric of the world we live in. It expands the dimensions of what Kauffman has called the ”adjacent possible” in almost unlimited ways, making almost any conceivable causal linkage possible (at least on a human scale).

In this respect, we can describe interpretation as the incorporation of some extrinsically available constraint to help organize work to produce other constraints that in turn help to organize additional work which promotes the maintenance of this reciprocal linkage between forms of work and constraint. So, unlike a thermostat, where the locus of interpretive activity is extrinsic to the cycle of physical interactions, an interpretive process is characterized by an entanglement between the dynamics of its responsiveness to an extrinsic constraint and the dynamics that maintains the intrinsic constraints that enable this responsiveness. Information is in this way indirectly about the conditions of its own interpretation, as well as about something else relevant to these conditions. Interpreting some constraint as being about something else is thus a projection about possibility in two ways: it is a prediction that the source of the constraint exists; and also that it is causally relevant to the preservation of this projective capacity. But a given constraint is information to an interpretive process regardless of whether these projected relations.h.i.+ps are realized. What determines that a given constraint is information is that the interpretive process is organized so that this constraint is correlated with the generation of work that would preserve the possibility of this process recurring under some (usually most) of the conditions that could have produced this constraint.

For this reason, interpretation is also always in some sense normative and the relations.h.i.+p of aboutness it projects is intrinsically fallible. The dynamical process of interpretation requires the expenditure of work, and in this sense the system embodying it is at risk of self-degradation if this process fails to generate an outcome that replenishes this capacity, both with respect to the constraints and the energy gradient that are required. But the constraint that serves as the sign of this extrinsic feature is a general formal property of the medium that embodies it, and so it cannot be a guarantee of any particular specific physical referent existing. So, although persistence of the interpretive capacity is partly conditional on this specificity, that correlation may not always hold.

The interpretive capacity is thus a capacity to generate a specific form of work in response to particular forms of system-extrinsic constraints in such a way that this generates intrinsic constraints that are likely to maintain or improve this capacity. But, as we have seen, only morphodynamic processes spontaneously generate intrinsic constraints, and this requires the maintenance of far-from-equilibrium conditions. And only teleodynamic systems (composed of reciprocal morphodynamic processes) are capable of preserving and reproducing the constraints that make this preservation possible. So a system capable of interpreting some extrinsic constraint as information relevant to this capability is necessarily a system dependent on being reliably correlated in s.p.a.ce and time with supportive non-equilibrium environmental conditions. Maintaining reliable access to these conditions, which by their nature are likely to be variable and transient, will thus be aided by being differentially responsive to constraints that tend to be correlated with this variability.

Non-living cybernetic mechanisms exhibit forms of recursive dynamical organization that generate attractor-mediated behavior, but their organization is not reflexively dependent on and generated by this dynamics. This means that there is no general property conveyed by each component dynamical transition from one state of the mechanism to the next. Only a specific dynamical consequence.

As Gregory Bateson emphatically argued, confusing information processes with energetic processes was one of the most problematic tendencies of twentieth-century science. Information and energy are distinct and in many respects should be treated as though they occupy independent causal realms. Nevertheless, they are in fact warp and weft of a single causal fabric. But unless we can both clearly distinguish between them and demonstrate their interdependence, the realms they exemplify will remain isolated.

INTERPRETATION.

For engineering purposes, Shannon's a.n.a.lysis could not extend further than an a.s.sessment of the information-carrying capacity of a signal medium, and the uncertainty that is reduced by receipt of a given signal. Including referential considerations would have introduced an infinite term into the quantification-an undecidable factor. What is undecidable is where to stop. There are innumerable points along a prior causal history culminating in the modification of the sign/signal medium in question, and any of these could be taken to be the relevant reference. The process we call interpretation is what determines which is the relevant one. It must ”pick” one factor in the trail of causes and effects leading up to the constraint reflected in the signal medium. As everyday experience makes clear, what is significant and what is not depends on the context of interpretation. In different contexts and for different interpreters, the same sign or signal may thus be taken to be about very different things. The capacity to follow the trace of influences that culminated in this particular signal modification in order to identify one that is relevant is in this way entirely dependent on the complexity of the interpreting system, its intrinsic information-carrying/producing capacity, and its involvement with this same causal chain.

Although the physical embodiment of a communication medium provides the concrete basis for reference, its physical embeddedness also opens the door to an open-ended lineage of potentially linked influences. To gain a sense of the openness of the interpretive possibilities, consider the problem faced by a detective at a crime scene. There are many physical traces left by the interactions involved in the critical event: doors may have been opened, furniture displaced, vases knocked over, muddy footprints left on a rug, fingerprints on the doork.n.o.b, filaments of clothing, hair, and skin cells left behind during a struggle, and so on. One complex event is reflected in these signs. But for each trace, there may or may not be a causal link to this particular event of interest. Each will also have a causal history that includes many other influences. The causal history reflected in the physical trace taken as a sign is not necessarily relevant to any single event, and which of the events in this history might be determined to be of pragmatic relevance can be different for different interpretive purposes and differently accessible to the interpretive tools that are available.

This yields another stricture on the information interpretation process. The causal history contributing to the constraints imposed on a given medium limits, but does not specify, what its information can be about. That point in this causal chain that is the referent must be determined by and with respect to another information process. All that is guaranteed by a potential reduction of the Shannon entropy of a signal is a possible definite linkage to something else. But this is an open-ended set of possibilities, only limited by processes that spontaneously obliterate certain physical traces or that block certain physical influences. Shannon information is a function of the potential variety of signal states, but referential entropy is additionally a function of the potential variety of factors that could have contributed to that state. So what must an interpretive process include in order to reduce this vast potential entropy of possible referents?

In the late nineteenth-century world of the fictional detective Sherlock Holmes, there were far fewer means available to interpret the physical traces left behind at a crime scene. Even so, to the extent that Holmes had a detailed understanding of the physical processes involved in producing each trace, he could use this information to extrapolate backwards many steps from effect to cause. This capacity has been greatly augmented by modern scientific instruments that, for example, can determine the chemical const.i.tution of traces of mud, the manufacturer of the fibers of different fabrics, the DNA sequence information in a strand of hair, and so on. With this expansion of a.n.a.lytic means, there has come an increase in the amount of information which can be extracted from the same traces that the fictional Holmes might have encountered. These traces contain no more physical differences than they would have in the late nineteenth century; it is simply that more of these have become interpretable, and to a greater causal depth. This enhancement of interpretive capacity is due to an effective increase in the interpretable Shannon entropy. But exactly how does this expansion of a.n.a.lytic tools effectively increase the Shannon entropy of a given physical trace?

Although from an engineer's perspective, every possible independent physical state of a system must be figured into the a.s.sessment of its potential Shannon entropy, this is an idealization. What matters are the distinguishable states. The distinguishable states are determined with respect to an interpretive process that itself must also be understood as a signal production process with its own potential Shannon entropy. In other words, one information source can only be interpreted with respect to another information production process. The maximum information that can be conveyed is consequently the lesser of the Shannon entropies of the two processes. If the receiving/interpreting system is physically simpler and less able to a.s.sume alternative states than the sign medium being considered, or the relative probabilities of its states are more uneven (i.e., more constrained), or the coupling between the two is insensitive to certain causal interactions, then the interpretable entropy will be less than the potential entropy of the source. This, for example, happens with the translation of DNA sequence information into protein structure information. Since there are sixty-four possible nucleotide triplets (codons) to code for twenty amino acids, only a fraction of the possible codon entropy is interpretable as amino acid information.2 One consequence of this is that scientists using DNA sequencing devices have more information to work with than does the cell that it comes from.

This limitation suggests two interesting a.n.a.logies to the thermodynamic constraints affecting work that were implicit in Shannon's a.n.a.lysis. First, the combined interpretable Shannon entropy of a chain of systems (e.g., different media) through which information is transferred can be no greater than the channel/signal production device with the lowest entropy value. Each coupling of system-to-system will tend to introduce a reduction of the interpretable entropy of the signal, thus reducing the difference between the initial potential and final received signal entropy. And second, information capacity tends to be lost in transfer from medium to medium if there is noise or if the interpreting system is of lower entropy (at least it cannot be increased), and with it the specificity of the causal history that it can be about. Since its possible reference is negatively embodied in the form of constraints, what a sign or signal can be about tends to degrade in specificity spontaneously with transmission or interpretation. This latter tendency parallels a familiar thermodynamic tendency which guarantees that there is inevitably some loss in the capacity to do further work in any mechanical process. This is effectively the informational a.n.a.logy to the impossibility of a perpetual motion machine: interpretive possibility can only decrease with each transfer of constraints from one medium to another.

This also means that, irrespective of the amount of Shannon information that can be embodied in a particular substrate, what it can and cannot be about also depends on the specific details of the medium's modifiability and its capacity to modify other systems. We create instruments (signal receivers) whose states are affected by the physical state of some process that we wish to monitor and use the resulting changes of the instrument to extract information about that phenomenon, by virtue of its special sensitivities to its physical context. The information it provides is thus limited by the instrument's material properties, which is why the creation of new kinds of scientific instruments can produce more information about the same objects. The expansion of reference that this provides is implicit in the Shannon-Boltzmann logic. So, while the material limits of our media are a constant source of loss in human information transmission processes, they are not necessarily a serious limitation in the interpretation of natural information sources, such as in scientific investigations. In nature, there is always more Boltzmann entropy embodied in an object or event treated as a sign than current interpretive means can ever capture.

NOISE VERSUS ERROR.

One of the clearest indications that information is not just order is provided by the fact that information can be in error. A signal can be corrupted, its reference can be mistaken, and the news it conveys can be irrelevant. These three normative (i.e., evaluative) a.s.sessments are also hierarchically dependent upon one another.

A normative consideration requires comparison. This isn't surprising since it too involves an interpretation process, and whatever information results is a function of possibilities eliminated. Shannon demonstrated that unreliability in a communication process can be overcome by introducing a specified degree of redundancy into the signal, enabling an interpreter to utilize the correlations among similar components to distinguish signal from noise. For any given degree of noise (signal error) below 100 percent, there is some level of redundant transmission and redundancy checking that can distinguish signal from noise. This is because the only means for a.s.sessing accuracy of transmission irrespective of content is self-consistency. If a communication medium includes some degree of intrinsic redundancy, such as involving only English sentences, then errors such as typos are often easy to detect and correct irrespective of the content. Because this process is content-independent, it is even possible to detect errors in encrypted messages before they are decoded. Errors in transmission or encoding that result from sources such as typing errors, transmission errors, or receiving errors will be uncorrelated with each other in each separate transmission, while the specific message-carrying features will be highly correlated from one replica to another.

This logic is not just restricted to human communication. It is even used by cells in cleaning up potentially noisy genetic information, irrespective of its function. This is possible because the genetic code is redundant, such that nucleotides on either side of the double helix molecule must exactly complement one another or the two sides can't fully re-anneal after being separated during decoding. Thus a mechanism able to detect non-complementarity of base pairing can, irrespective of any functional consequence, be evolved to make functional repairs, so long as the damage is not too extensive.

There is a related higher-order logic involved in checking the accuracy of representation. Besides the obvious utility of being able to determine the accuracy of information about something, this issue has important philosophical significance as well. The a.s.sessment of referential error has been a non-trivial problem for correspondence and mapping theories of reference since at least the writings of the philosopher David Hume in 173940. This is because a correspondence is a correspondence, irrespective of whether it is involved in a representational relations.h.i.+p or is of any significance for any interpretive process. In some degree or other, it is possible to find some correspondence relation between almost any two facts. What matters is the determination of a specific correspondence, and this requires a means for distinguis.h.i.+ng accurate correspondence relations.h.i.+ps and ignoring spurious ones. The solution to this problem has a logic that is a.n.a.logous to correcting for signal noise in Shannon's theory.

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