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>Computation is something that a computer provably does. This is a circular definition. In order to properly define the concept, we must be able to word it wit

by Tryk 5mo ago

>Computation is something that a computer provably does. This is a circular definition. In order to properly define the concept, we must be able to word it without using "computing devices" in the definition. Finding a satisfactory definition for what constitutes a "Computation" is actually an interesting debate goes back to the 1600s. Currently, the mainstream definition (from wikipedia) gives that: "A computation is any type of arithmetic or non-arithmetic calculation that is well-defined". One way to understand the author is to learn more about the "The mapping account" theory behind computation: "a physical system can be said to perform a specific computation when there is a mapping between the state of that system and the computation such that the 'microphysical states [of the system] mirror the state transitions between the computational states.'"

tsimionescu 5mo ago
I wasn't trying to use that as a definition of what computation means. My point is that regardless of how we define it, the fact is that the devices we build to do some form of computation are objectively successful at doing what they were built to do. For example, you can say that Firefox is a human-centric abstraction, and that my computer isn't running Firefox right now in an objective sense, that this is is just a human-centric interpretation of what the physical device is doing, and that there exist other computations that we could assign to it. But what you can't say is that the device is not affecting the physical world in ways that are consistent with performing the Firefox computation, such as causing certain specific wavelengths of light to be emitted by the screen based on state that is stored in a server in the YCombinator data center. This is a measurable fact of the physical world that is independent of the model of computation you chose to ascribe to the physical device - any consistent mapping will have to preserve this same physical property.
- bch8_ 5mo ago
  The paper addresses this point in section 3.2. They aren't debating the fact that a physical process is taking place in a computer running a program. They are arguing that the semantic interpretation of the output of that program is indeterminate and dependent on the mapping function: > A single physical vehicle (bottom) possesses a fixed causal trajectory. However, it does not instantiate a unique computation. Depending on the alphabetization key applied (fA or fB ), the same physical states can be mapped to entirely different abstract computations (Top Left vs. Top Right). Therefore, computation cannot be intrinsic to the physics (p). So yes there is a physical process generating your Firefox browser, but there is also a mapping function taking that program and interpreting that it should display your Firefox browser. There are any number of mapping functions that could be applied to the physical state in order to display other things on your screen besides the browser. Therefore, the Firefox browser being displayed is not inherent or intrinsic to the physical state of your computer. If we did not have the right mapping function, we would have no way of knowing or inferring or discovering which mapping function is correct.
  - tsimionescu 5mo ago
    But the results that the computer screen shows, and the inputs fed into the machine, are entirely physical, observer-independent processes. Just like an inscribed papyrus contains letters in a physically observable, provable sense - even if the semantics of those letters are entirely man made. This is in fact very similar to the notion of text - text is a physical medium, that provably contains a message that one human intended to convey to other humans. The same physical text can be interpreted in an infinite number of ways, and they are all equally valid in that they are self-consistent, but only one is the intention of the original author.
    - bch8_ 5mo ago
      To the best of my understanding I believe the response from the position taken by the paper is that this is still committing the abstraction fallacy (Assuming you aren't just agreeing with them here, which I don't think you are). The book itself doesn't physically instantiate the information it contains in its text. In a vacuum it is informationally inert. That doesn't mean it doesn't physically exist. Likewise the computer running Firefox obviously physically exists. The fallacy is the next jump from there - assuming that the semantic content of the book or software is physically present in those items. Another example given in the article is an analog clock: > Consider an analog clock. Physically, the device is a collection of gears and springs governed by continuous dynamics (P). It only “computes” time because a mapmaker intervenes, mapping a specific set of continuous angles to a semantic concept (e.g., “3:00 PM”). Without this semantic imposition, the clock is just metal moving in accordance with Hamilton’s equations; it contains no intrinsic “time.” Thus, the physical substrate does not “process information” absent a prerequisite alphabet of intrinsic symbols; rather, it generates continuous dynamics that an external mapmaker interprets as information. In this example the time "3:00 PM" is instantiated in the mind of the person reading the clock, it is not a real physical property of the clock itself.
      - Teever 5mo ago
        If this mechanical clock mechanism was part of some sort of Von Neumann probe that was sitting dormant in a star system waiting for the clock to strike a specific time and when that occurs it triggers another mechanism in the probe that combines stored nucleotides to produce a particular sequence of RNA and DNA that is seeded into a suitable world and that soup of RNA and DNA eventually evolves into intelligent biological life that finds the Von Neumann probe and learns to interpret the symbols and purpose of the probe and comes to understand what 3:00 PM means, does that whole system have the real physical property of 3:00 PM in it?

by Tryk 5mo ago

tsimionescu 5mo ago

I wasn't trying to use that as a definition of what computation means. My point is that regardless of how we define it, the fact is that the devices we build to do some form of computation are objectively successful at doing what they were built to do. For example, you can say that Firefox is a human-centric abstraction, and that my computer isn't running Firefox right now in an objective sense, that this is is just a human-centric interpretation of what the physical device is doing, and that there exist other computations that we could assign to it. But what you can't say is that the device is not affecting the physical world in ways that are consistent with performing the Firefox computation, such as causing certain specific wavelengths of light to be emitted by the screen based on state that is stored in a server in the YCombinator data center. This is a measurable fact of the physical world that is independent of the model of computation you chose to ascribe to the physical device - any consistent mapping will have to preserve this same physical property.

bch8_ 5mo ago
The paper addresses this point in section 3.2. They aren't debating the fact that a physical process is taking place in a computer running a program. They are arguing that the semantic interpretation of the output of that program is indeterminate and dependent on the mapping function: > A single physical vehicle (bottom) possesses a fixed causal trajectory. However, it does not instantiate a unique computation. Depending on the alphabetization key applied (fA or fB ), the same physical states can be mapped to entirely different abstract computations (Top Left vs. Top Right). Therefore, computation cannot be intrinsic to the physics (p). So yes there is a physical process generating your Firefox browser, but there is also a mapping function taking that program and interpreting that it should display your Firefox browser. There are any number of mapping functions that could be applied to the physical state in order to display other things on your screen besides the browser. Therefore, the Firefox browser being displayed is not inherent or intrinsic to the physical state of your computer. If we did not have the right mapping function, we would have no way of knowing or inferring or discovering which mapping function is correct.
- tsimionescu 5mo ago
  But the results that the computer screen shows, and the inputs fed into the machine, are entirely physical, observer-independent processes. Just like an inscribed papyrus contains letters in a physically observable, provable sense - even if the semantics of those letters are entirely man made. This is in fact very similar to the notion of text - text is a physical medium, that provably contains a message that one human intended to convey to other humans. The same physical text can be interpreted in an infinite number of ways, and they are all equally valid in that they are self-consistent, but only one is the intention of the original author.
  - bch8_ 5mo ago
    To the best of my understanding I believe the response from the position taken by the paper is that this is still committing the abstraction fallacy (Assuming you aren't just agreeing with them here, which I don't think you are). The book itself doesn't physically instantiate the information it contains in its text. In a vacuum it is informationally inert. That doesn't mean it doesn't physically exist. Likewise the computer running Firefox obviously physically exists. The fallacy is the next jump from there - assuming that the semantic content of the book or software is physically present in those items. Another example given in the article is an analog clock: > Consider an analog clock. Physically, the device is a collection of gears and springs governed by continuous dynamics (P). It only “computes” time because a mapmaker intervenes, mapping a specific set of continuous angles to a semantic concept (e.g., “3:00 PM”). Without this semantic imposition, the clock is just metal moving in accordance with Hamilton’s equations; it contains no intrinsic “time.” Thus, the physical substrate does not “process information” absent a prerequisite alphabet of intrinsic symbols; rather, it generates continuous dynamics that an external mapmaker interprets as information. In this example the time "3:00 PM" is instantiated in the mind of the person reading the clock, it is not a real physical property of the clock itself.
    - Teever 5mo ago
      If this mechanical clock mechanism was part of some sort of Von Neumann probe that was sitting dormant in a star system waiting for the clock to strike a specific time and when that occurs it triggers another mechanism in the probe that combines stored nucleotides to produce a particular sequence of RNA and DNA that is seeded into a suitable world and that soup of RNA and DNA eventually evolves into intelligent biological life that finds the Von Neumann probe and learns to interpret the symbols and purpose of the probe and comes to understand what 3:00 PM means, does that whole system have the real physical property of 3:00 PM in it?