A question for Winston Ewert

Added June 17, 2015: Jump in with whatever comments you like, folks. Dr. Ewert has responded nebulously at Uncommon Descent. I’d have worked with him to get his meaning straight. I’m not going to spend my time on deconstruction. However, I will take quick shots at some easy targets, mainly to show appreciation to Lizzie for featuring this post as long as she has. Here, again, is what I put to Dr. Ewert:

Your “search” process decides when to stop and produce an outcome in the “search space.” A model may do this, but biological evolution does not. How do you measure active information on the biological process itself? Do you not reify a model?

Dr. Ewert seemingly forgets that to measure active information on a biological process is to produce a specific quantity, e.g., 109 bits.

One approach is to take the search space not to be the individual organisms, but rather the entire population of organisms currently alive on earth. Or one could go further, and take it to be the history of organisms during the whole of biological evolution. One could also take it to be possible spacetime histories. The target can then be taken to be spacetimes, histories, or populations that contain an individual organism type such as birds.

These “search spaces” roll off the tongue. But no one knows, or ever will know, what they actually contain. Even if we did know, no one would know the probabilities required for calculation of the active information for a given target. And even if we did know the probability of a given “target” for a given “search,” we would not be able to justify designating a particular probability distribution on the search space as the “natural” baseline. By the way, Dr. Ewert should not be alluding to infinite sets, as his current model of search applies only to finite sets.

Another possibility is to model evolution as a process which halts upon finding the target, but distinguish between the active information derived from the evolutionary process itself and the active information contributed by the stopping behavior. The stopping behavior cannot induce birds to show up in the first place, it can only select them as the output of the search when they arrive. By looking at the number of opportunities for birds to arise, we can determine how much active information was added by the stopping process. It was shown in “Conservation of Information in Search: Measuring the Cost of Success” that the active information available from such a process is only the logarithm of the number of queries. Any other active information must derive from the evolutionary search itself.

Dembski and Marks define search differently in the cited paper than Dembski, Ewert, and Marks do. The result that Dr. Ewert invokes does not apply to the active information of a search, as presently defined. With the current definition, we can specify a process that goes through elements of the finite search space, one by one, until it recognizes an element of the target. Then the active information of the process is due almost entirely to recognition of the target by the “stopping process.” I hope this gives you some idea of what’s wrong with Ewert’s claim. Perhaps one of the cognoscenti will supply more of the details in a comment.

Both approaches effectively end up adjusting for the number of trials. Getting a royal flush is improbable, but if you play five million hands of poker it is no longer surprising. Similarly, obtaining a bird is rendered much more probable given the number of chances for it happen in the history of universe. It is a very important point to keep in mind that we cannot simply look at the probability of the individual events but also the number of trials.

Dr. Ewert errs, and has brought to the fore a major weakness of the current definition of search. Here the search space is the set of all five-card poker hands, and the target is the subset containing the royal-flush hands. A search that halts after one step and yields a royal flush with probability 1/2 has exactly the same active information as a search that yields a royal flush with probability 1/2 after five million or fewer steps. In short, a “very important point to keep in mind” is that the number of trials actually does not enter into the calculation of active information.

For birds to have been produced by an evolutionary process, the universe must have been biased towards producing birds.

Must the universe have been biased against producing “flying insects that walk on all fours”? (This is not a cheap dig at religion, but instead a substantive response to Robert “Saying the Bible is not a book about science is like saying a cookbook is not a book about chemistry” Marks. I had forgotten Leviticus 11:20 until I Googled for scientific discussion of why there are no four-legged insects.)

The original post follows.


I actually have three technical questions for Winston, but plan on one post apiece. He should respond first to questions he receives through Google Moderator, including those from DiEb, who has added a relevant post to his blog. Hopefully he will join us here when he’s done with that.

Let’s be clear from the outset that off-topic remarks go straight to Guano. (If you attack Winston personally while I am trying to draw him into a discussion of theory, then I will take it personally.) You shouldn’t make claims unless you have read, and believe that you mostly understand, the material in all three sources in note 3, apart from the proofs of theorems. Genuine requests for explanation are, of course, welcome. They’re especially welcome if you’ve made a genuine effort to get what you can from the sources.

The overall thrust of my questions should be clear enough to Winston, though it won’t be to most readers. I’m definitely not laying a trap for him. The first two questions have answers that are provably right or wrong. The third is more a matter of scientific modeling than of math. I’m starting with it because TSZ isn’t yet configured to handle embedded LaTeX (mathematical expressions).

Questions
[We discuss only the highlighted question in this thread.]

1. What is the formal relationship between active information and specified complexity?

2. What is the formal relationship between active information and average active information per query? Does the conservation-of-information theorem apply to the latter?

3. Your “search” process decides when to stop and produce an outcome in the “search space.” A model may do this, but biological evolution does not. How do you measure active information on the biological process itself? Do you not reify a model?

Notes
[Numbered to indicate correspondence to the questions.]

1. There’s an answer that covers both Dembski’s 2005 version (the probabilistic complexity minus the descriptive complexity of the target) and the algorithmic version of specified complexity. For the latter, it’s apparently necessary to restrict the target (no longer called a target) to a single-element set.

2. The conservation-of-information theorem applies to active information. Winston and his colleagues have measured only average active information per query (several closely related forms, actually), which seems unrelated to active information, in their analyses of computational evolution and metabiology. Yet they refer to “conservation of information” in exposition of those analyses.

3. The “search” process of Dembski, Ewert, and Marks terminates, and generates an outcome. The terminator and the discrim­inator of the “search” in fact contribute to its “active information” — bias, relative to a baseline distribution on outcomes, in favor of a “target” event. However, biological evolu­tion has not come to a grinding halt, and has not announced, for instance, “Here it is — birds!” It seems that Winston, in his ENV response to a Panda’s Thumb post by Joe Felsenstein and me, tacitly assumes that a biologist has provided a model that he can analyze as a “search,” and imputes to nature itself the bias that he would measure on the model of nature. If so, then he erroneously treats an abstraction as though it were something real. Famously, “The map is not the territory.” Perhaps Winston can provide a good argument that he hasn’t lapsed into reification.

30 thoughts on “A question for Winston Ewert

  1. Tom,
    QuickLatex is installed and operational. All you need do is activate a post or comment with {latexpage} (substitute square brackets) and it should work fine. You should be able to see the Quicklatex options in the admin panel.

  2. Joe Felsenstein:
    Did you just ask one question per post, or three?

    I’ve added some clarification in square brackets. I think it’s good to let Winston know up front what questions I’d like to see him answer.

    Does this look familiar?

         \begin{align*} N^\prime_1 &= W_t N_1, \\ \mathrm{and} \\ N^\prime_2 &= W_t N_2. \end{align*}

    [Edit: Joe remarks below that the formatting didn’t work. I got it to work by putting the “fancy” LaTeX between {latex} and {/latex} (replace curly braces with square braces). See the QuickLaTeX guide.]

  3. Elizabeth:
    I’m happy to leave it stickied.I know (lol) how easy it is to lose contact with a thread or blog when stuff intervenes.

    Thanks for keeping the welcome mat out. I check UD, ENV, Google Moderator, and this thread several times a day.

  4. Joe Felsenstein:
    Google is closing down Moderator by June 30.Which might complicate matters.

    That shouldn’t be a problem, as Winston said:

    I plan to leave the poll up for about and week and the evaluating answering some of the questions.

    So, any minute now……

  5. I tried posting the following at UD.

    “Even if Dr. Ewert is uncomfortable participating at TSZ would he give permission (approval) to replicate his post verbatim at TSZ. I know that permission isn’t technically needed, but it would show good faith on both sides.

    I don’t expect anyone will see this given that Barry, for whatever reason, refuses to allow any of my posts past his moderation. But I will duplicate this comment at TSZ as it is obvious that Dr. Ewert looks at it. “

    I should mention that My comments no longer go into moderation. They just disappear.

  6. Elizabeth: If he prefers not to do this, then I hope he will at least engage with this thread.

    Perhaps we should copy and paste his OP into a thread here. [Snark deleted]

  7. I guess there might be copyright issues.

    There’s a link here, and this thread is stickied. Let’s just use this, unless he wants to post an OP himself,.

  8. Dembski and Marks have defined active information in three distinct ways. The definitions are not formally equivalent.

    I’ll assume that Winston did not gather from the OP that I was referring to the most recent definition — the one for which there’s a “conservation of information” theorem, and the one in the analytic framework Dembski told me he’d use in future work, and the one to which Joe and I responded in our PT post, and the one Winston presumably had in mind in his ENV response to Joe and me (else why would he respond?). However, that does not give him license to use the term active information equivocally, as he has at UD.

    I’ll repeat my commitment to maintaining a purely technical discussion. I’ve demonstrated above that I will object to minimal snark, irrespective of the source. And I’ve provided in this comment a taste of technical criticism.

    [Edit: The place for snark, and for meta-commentary in general, is the Sandbox.]

  9. Elizabeth:
    Winston Ewert has responded at UD, and I have suggested he cross-posts his reponse here.
    Dr. Ewert Answers

    If he prefers not to do this, then I hope he will at least engage with this thread.

    Apparently Barry doesn’t like you doing this. Although, as is normal, he completely misrepresents your comment.

    UDEditors: Elizabeth, if you don’t want to post your incoherent blitherings on these pages, then by all means do not. But this silliness of putting up post after post about how you are afraid to post here must stop. Only warning.

  10. Cross-post from UD:

    roma locuta causa finita? Winston, I’m sorry that this experiment was not as successful as you hoped, but I’m afraid it will be even less a success if you don’t intend to follow up….

    OTOH: if you think that you are finished with the questions, then it is really of no importance which venue you have chosen, UD or TSZ.

  11. DiEb and keiths,

    I hope you guys will fill in some detail. I’ve got something else I need to give higher priority.

    DiEb, I know that you’ve blogged on the weird consequences of requiring the “search” to select one of the sampled elements of the “search space.”

  12. Tom English:

    These “search spaces” roll off the tongue. But no one knows, or ever will know, what they actually contain. Even if we did know, no one would know the probabilities required for calculation of the active information for a given target. And even if we did know the probability of a given “target” for a given “search,” we would not be able to justify designating a particular probability distribution on the search space as the “natural” baseline.

    Dembski’s entire career is marred by his inability to calculate the probabilities he needs to get his ideas off the ground.

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