Theistic evolution and purpose

35


Discussion by: Bahraini

I have finally read a book on theistic evolution. The strongest argument is that evolution has a purpose. So you ask, how's that?

The author argues that the best instrument to survive is intelligence (evidence for this is that humans, who lack many advanced instruments [claws, eyes, echo, etc] that other animals have, are dominant – he treats this as an obvious fact), therefore those with higher intelligence are favored by natural selection. Even if this takes very long time, in the end natural selection will favor intelligence in the form of simple nervous system, which can connect and coordinate the various instruments. 

As natural selection progresses, more intelligent animals will evolve and finally we have homo sapiens. Even if it weren't homo sapiens, the author argues, it would have been another animal that would have been able to talk, interact, think, etc, and therefore would be able to recognize and pray to god.

What do you think?

35 COMMENTS

  1. Dumb and old. They’re just finding excuse to reach the conclusion they want. Actually, it would be a lot more advantageous to develop psychic powers and telepathy than dexterity and speech, so why haven’t we evolved those?

    • In reply to #1 by adiroth:

      Actually, it would be a lot more advantageous to develop psychic powers and telepathy than dexterity and speech, so why haven’t we evolved those?

      According to occultist we have. And I have had some shocking results using telepathy although I have just recently started and my experiences so far could easily written off as coincidence. In school, I have seemingly influenced seating charts and interactions with other people. If you want a scientific explanation on how this would work there are several theories, most using quantum physics and I don’t see how any could be confirmed. Most people who practice these “psychic powers” argue and complain that we are behind in this field because of the close-minded skepticism of many scientist, and honestly only someone with an extremely opened mind, which I would say I have, or a childish mind would even consider the possibility.

      • In reply to #28 by Black Sheep:

        In reply to #1 by adiroth:

        Actually, it would be a lot more advantageous to develop psychic powers and telepathy than dexterity and speech, so why haven’t we evolved those?

        According to occultist we have. And I have had some shocking results using telepathy although I have just recently started…

        There is another explanation. Research Skinner’s pigeons.

      • In reply to #28 by Black Sheep:
        >

        Most people who practice these “psychic powers” argue and complain that we are behind in this field because of the close-minded skepticism of many scientists, and honestly only someone with an extremely opened mind, which I would say I have, or a childish mind would even consider the possibility.

        There are minds which are open to evidence and reason – and then there are minds which are like slop-buckets with no lid – Open to anything!
        Quackologists and faith-heads, frequently demand, (with tones of self flattering superiority), that other people should have the latter, – in order to make their circular arguments and faith-based whimsicalities acceptable!

  2. The argument is that natural selection favours ‘high-level’ intelligence? (I don’t believe that is established, by the way.) How is that supposed to provide evidence for a creator? If natural selection produces X, with or without Y, then the observation of X is neutral with respect to Y – we are left with only the uninformed priors (before X was observed).

    If the real argument is that natural selection had to be guided or intelligently set up, then fine, go make a case for that. But don’t just assume it, and pretend you haven’t. It sounds like the author of that book is either very stupid or very dishonest.

  3. I did’t read. What is the name of that book??
    The argument that the best instrument to survive is intelligence is not true. What is about the viruses, the bacteria and the other microbes?? They ‘want’ to be simply, because simplicity allows him to survive.

  4. @OP – As natural selection progresses, more intelligent animals will evolve and finally we have homo sapiens. Even if it weren’t homo sapiens, the author argues, it would have been another animal that would have been able to talk, interact, think, etc, and therefore would be able to recognize and pray to god.

    That is the purely asserted unevidenced basis of the circular argument, along with a profound ignorance of biology.

    Gods and theistic purposes of producing human worshippers, are the imaginary pseudo-science infusions, which are the centre-piece of the human centred theist pseudo-biology – totally ignoring the actual biology and evolution, which contradicts this nonsense. Single cells and viruses far outnumber, and out-pace humans, in successful geographical colonisation, existence in deep time, and evolutionary survival prospects.

    It is the usual “humans and my theist cult, are my god’s pet master-race of creatures” story, so lets cobble some pseudo-science around that, try to massage some human egos to add some confirmation-bias, and assert delusional human evolutionary superiority over other life forms.

    • In reply to #5 by Alan4discussion:
      What you said is nearly the same ideas that flouted through my mind when I first read it. It would be useful if more writing is devoted againt theistic evolution rather than the creationists.

      • In reply to #8 by Bahraini:

        In reply to #5 by Alan4discussion:
        What you said is nearly the same ideas that flouted through my mind when I first read it. It would be useful if more writing is devoted against theistic evolution rather than the creationists.

        The problem is, as with many forms of theistic pseudo-science, unlike the simplistic fundamentalists, the theistic evolution brigade, shift and shuffle with lots of double-talk and self contradiction, remaining vague about how their claims are supposed to work.

        Even those like the Roman Catholic Church which claims in writing to accept the science,

        The Church has deferred to scientists on matters such as the age of the earth and the authenticity of the fossil record. Papal pronouncements, along with commentaries by cardinals, have accepted the findings of scientists on the gradual appearance of life. In fact, the International Theological Commission in a July 2004 statement endorsed by Cardinal Ratzinger, then president of the Commission and head of the Congregation for the Doctrine of the Faith, later Pope Benedict XVI, now Pope Emeritus Benedict XVI, includes this paragraph:

        According to the widely accepted scientific account, the universe erupted 15 billion years ago in an explosion called the ‘Big Bang’ and has been expanding and cooling ever since. Later there gradually emerged the conditions necessary for the formation of atoms, still later the condensation of galaxies and stars, and about 10 billion years later the formation of planets. In our own solar system and on earth (formed about 4.5 billion years ago), the conditions have been favorable to the emergence of life. While there is little consensus among scientists about how the origin of this first microscopic life is to be explained, there is general agreement among them that the first organism dwelt on this planet about 3.5–4 billion years ago. Since it has been demonstrated that all living organisms on earth are genetically related, it is virtually certain that all living organisms have descended from this first organism. Converging evidence from many studies in the physical and biological sciences furnishes mounting support for some theory of evolution to account for the development and diversification of life on earth, while controversy continues over the pace and mechanisms of evolution.[6]

        The Church’s stance is that any such gradual appearance must have been guided in some way by God, but the Church has thus far declined to define in what way that may be. Commentators tend to interpret the Church’s position in the way most favorable to their own arguments.

        The RCC then goes on to say that in unspecified ways, loads of “truly scientific” supernatural miracles and “god-did-it” are somehow included in this “science”.

        Catholic teaching and evolution

        .159. Faith and science: “… methodical research in all branches of knowledge, provided it is carried out in a truly scientific manner and does not override moral laws, can never conflict with the faith, because the things of the world and the things of faith derive from the same God. The humble and persevering investigator of the secrets of nature is being led, as it were, by the hand of God in spite of himself, for it is God, the conserver of all things, who made them what they are.” (Vatican II GS 36:1)

        This is of course double-talk rubbish, as scientific methodology has nothing to do with the preconceptions of faith! You cannot “accept the science”, only if it has faith as a preconceived basis, contradicting scientific methodology, as in such circumstances, it is no longer science, – but they simply falsely claim that it is TRRRrrrooooo science – with the usual theist semantic obfuscation!

  5. Tardigrades have survived for 3 billion years, humans for perhaps 3 hundred thousand, if that. Does not say much for the power of intelligence. Or against it either. I suspect your unnamed book says about the same.

  6. It’s bollocks Christian Science at its best. Putting the cart before the horses to reinforce their fantasy.

    The author argues that the best instrument to survive is intelligence (evidence for this is that humans, who lack many advanced instruments [claws, eyes, echo, etc] that other animals have, are dominant – he treats this as an obvious fact).

    You could argue the reverse and be as self-evident. Physical disadvantages would make better brains a requirement for survival. It’s not ‘the best’, it’s just one of many survival strategies. Both arguments BTW, are baseless.

    Even if it weren’t homo sapiens, the author argues, it would have been another animal that would have been able to talk, interact, think, etc, and therefore would be able to recognize and pray to god.

    Which is also why the ones we have always consider highly intelligent and ahead of the curve were all book-thumping God-botherers.

    Even if it weren’t homo sapiens, the author argues, it would have been another animal that would have been able to talk, interact, think, etc, and therefore would be able to recognize and do sexy science.

    It’s all backward and groundless.

  7. Just a suggestion when you are going to reference a book in a discussion topic it’s a good idea to give the name of the book so we can know what you are talking about. I’m not really sure what to make of your argument. You say some things about evolution that make me think perhaps you don’t really understand the basics. So for example when your second sentence is “The strongest argument is that evolution has a purpose. ” that makes me think perhaps you don’t really understand evolution. It depends what you mean by purpose in that sentence but if you mean that evolution has a “goal” to make organism better or even to make them smarter or stronger that isn’t really true. Evolution makes organisms better adapted to their environment. Being better adapted to your environment means you usually get stronger, faster, and smarter over time but not always. For example, there are fish that live in deep water and caves that lost the ability to see because they didn’t need it anyway.

  8. The fact that the book was written in Arabic in no way excuses it from pervaying nonsense ! Old Earth creationism is just as crazy as Young Earth creationism, – the only difference being some 13.82 billion years.

    As for the Creator “guiding” evolution, – what a cruel bastard He is ! Indeed it was the very cruelty of nature that turned Darwin against his own Christianity. He was an honest man.

    As usual with the religious apologists, they always find the answers to clashes, where their religion comes into conflict with knowledge, in retrospect ! Nothing useful ever came from Allah or Jesus about germ theory or electro-magnetic radiation. No, – real people had to work those things out !

  9. Bugs are more successful than Homo Sapiens (i.e population levels) so it would seem the purpose of evolution is to make as many bugs as possible. Homo Sapiens are probably just a symbiotic side effect and too big and fragile to survive much change so would not put any money on their long term survival. Bit of climate change will knock the HomoSapien numbers down and a bit more will easily wipe them out but the bugs will keep going.

  10. There term ‘scientism’ is often used by believers to scoff at science and scientists. Can science explain consciousness, love, literature, art and morality, they say. Theistic science, it seems to me, is what should be termed ‘scientism’. What does it add to our understanding of the universe to claim that a Big Banger set off the Big Bang? It isn’t helpful to claim that God caused life to bubble up when he gave the primordial soup a stir. It isn’t helpful except to religious organizations whose survival depends on preserving some remnants of belief in the reality of mythical beings and their doings.

  11. Life has had many false starts and revisions. Mass extinctions, global and local, resent evolution to run again and again. There has been 3.5 billion years of evolution and in that time, only once has a sentient intelligence popped up as an evolutionary advantage. It the authors premise was correct, and he understood the evolutionary process, we would have seen a steady serious of animals that used intelligence as their evolutionary advantage / niche, but we don’t. Dinosaur hieroglyphics. Whales pleading with the Japanese to stop slaughtering them. Bacteria that make a host very sick, but don’t kill it, and kill themselves at the same time. Burgess shale creatures with opposable thumbs. That’s because apart from one, every animal that has ever existed has done just fine with a nervous system driving various senses. That’s all an animal needs.

    But like all evolutionary advantages, they are always temporary. The arms race between predator and prey. Super bacteria because we are so stupid that we use disinfectants in every cleaning product. Ask the author if we are so intelligent, why we kill off the very environment that is essential to our survival. Doesn’t sound intelligent to me. Sounds stupid.

  12. Teleological arguments are fallacious because “purpose” is arbitrary and transient. Purpose is a perceived trait based on based on pattern recognition, perceived functionality and (presumably intelligent) intent. We may recognize purpose in an object or event. But things can be re-purposed. Things and events usually have effects beyond their original purpose. Future observers may conclude these extra effects were the true purpose. Which is correct? Neither… or perhaps both. The important point is that purpose is merely a subjective observation. Purpose cannot be objective as it cannot exist without a subjective observer. Even if we imagine an objective observer could exist, it could not identify purpose without consideration of how the effects of a thing or phenomenon impinge on one or more subjective observers.

    We can speculate that a master creator intended for evolution to produce what we recognize as intelligence. But whatever evidence one might offer to support that hypothesis supports natural hypotheses as well or better. Go ahead, give it a shot… I’ll wait. Let’s also consider that evolution has produced far more non-intelligent life much of which dies suffering.

    Intelligence also leads to philosophy which is far better at refuting the existence of a theistic god than supporting it.

    Intelligence also leads to science which has (and if I may suggest, will continue to) demystify everything that exists. Science’s inability to observe and measure God directly or indirectly suggests that God’s existence is negative or moot.

    Intelligence also does a poor job of pointing to any one particular god concept. Homo sapiens lived and died for a hundred thousand years before anyone even came up with the idea of YHWH, Allah or perhaps a yet undiscovered theistic god. In this way (and others) divinely initiated evolution is so inefficient as to be probably the worst way of producing worshipers.

  13. I’m quite fond of quite a few humans, but this is a demonstration of human arrogance at its best. The whole universe is about us, and I cannot have any reason to go on without this belief. Perhaps the author would care to explain the purpose of the Aids virus killing off all of those children, or the purpose of flesh eating flies? Perhaps it is just contrast how wonderful we are.

  14. If the Earth were to suffer a catastrophic impact from a comet or large asteroid, all life on this planet might be snuffed out except for some ‘extremophile’ bacteria. Do you think they would pray to their god(s)?

    It may be that by the time such a catastrophe occurs, mankind will have created a thinking machine. Unhindered by the slow pace of evolution this machine would have a level of knowledge and intelligence far superior to ours. It could survive the impact of a comet because it could be distributed around the globe (like the internet), or even live its ‘life’ in orbit. Powered by solar and nuclear energy it would outlive its human creators and might become the most intelligent thing in the universe. Should we program it to pray?

  15. therefore those with higher intelligence are favored by natural selection.

    One needs to define Higher Intelligence first. The way this is set up it makes me think of a Higher Authority…
    Then one must find out apart from what we consider Human intelligence and guess the level of intelligence of other organisms depending on how human they can be if we are the measuring stick.

    So there is a flaw or something is missing because there needs to be more subjects in a control study to be able to compare. That is difficult because we can only test animals based on how they learn repetition or training and to some degree communicate with us . One would need to measure intelligence based on what the creature needs to survive the hostile world. Much of this intelligence is instinct and innate . It increases as the creature learns and assimilates the best ways to survive based on each experience.

    Watching a herd of water buffalo protecting they young against a lion you can see that the calf that did not stay with in the protection grid was the one who the lions target. In this case the calf was not intelligent enough to stay in the grid and the lion is intelligent enough to know there will be a dumb one in the crowd and simply waits for the opportunity.
    Is this intelligence or instinct. Or learned behavior passed on. Doesn’t learning imply intelligence ?

    The real and only question then would be why us ? But then more questions come ….

    Why did we develop like this and not other animals ? Are we freaks of nature ? This world was made by god for us because there is nothing else like us or as intelligent as us , but why what for ? I need a purpose to live !!!!

    And are we alone in the universe or is there Intelligence out there… ? Intelligence like ours (discounting the nutters of course because that just spoils the pot. )

    I agree with some people here who posted humans are not good for this planet, it was not smart of god to make us that is for sure….And if we are made in his image that makes us dumb and him dumber. Unless of course he made us for the sole purpose of having people love him. Then that is cruel and unusual punishment for the rest of this planet just so he could have worshipers…

    As natural selection progresses, more intelligent animals will evolve and finally we have homo sapiens.

    No we have homo theosapiens as well apparently and they are not evolving fast enough as the fruit flies they tend to be…

    What about the theory that we have alien DNA and that is what made us smarter than the apes we were ? The missing link.. ?
    That is easier to believe than the god creator.

  16. The author argues that the best instrument to survive is intelligence (evidence for this is that humans, who lack many advanced instruments…

    best for whom? so far the “best” survival plan found is over 3 billion years old and needs only one cell, proved by the fact it’s the most abundant form. human intelligence has created a species that has covered the planet briefly. there are still snakes and crocs basking without a thought waiting for their next meal just like thier ancestors did 100,000,000 years ago

    therefore those with higher intelligence are favored by natural selection.

    wrong. dogs have less intelligence than their very close wolf cousins but have outcompeted them everywhere in the world. also if intelligence were so important it would be equally high in many other species. dolphins are quite intelligent but what’s most important for their survival is to be shaped a bit like their long-distant fish cousins (who are more numerous despite lacking dolphin brains)

    Even if it weren’t homo sapiens, the author argues, it would have been another animal that would have been able to talk, interact, think, etc, and therefore would be able to recognize and pray to god.

    maybe the first ones but if by “pray to god” he means, act in a superstitious way either out of fear of mortality or to attain a personal goal with no understanding of the process you need only look as far as elephants carrying the bones of relatives or the famous skinner box experiments with pigeons.

    so talk: maybe that’s human. interact: no, all social animals do that. Think: pointless trying to prove that’s a uniquely human ability. etc: stop using etc. as a way of making up for ignorance… but most importantly, to believe there’s a higher power that provides for you based only on your desires and actions, requires all the intelligence of a pigeon.

  17. “…and therefore would be able to recognize and pray to god.”

    Why are you even giving this book any sort of serious consideration?
    First you assume there is a god to pray to, second you assume the only “purpose” of evolution is to get to the stage where an organism can pray to god and thirdly (this is a big one) this is nothing to do with science.
    Assuming there is a god (big assumption) do you really think a creator would wait around for 4.6 billion years just to hear for those prayers come flooding in?
    Watching 99% of all species die off in the meantime?
    It sounds like a laboratory experiment designed by a self obsessed and insecure mad professor.

  18. The Accidental Mind: How Brain Evolution Has Given Us Love, Memory, Dreams, and God by David J. Linden. Cambridge, Mass, Harvard University, there are chapters in the book on brain assembly; sensation and emotion; learning, memory, and individuality; sleep, dreams, and their possible functions; and sex, love, and some of their varieties, the religious impulse. He proposes and discusses a potentially important neuro-biological contribution to the roots of religion – that the human brain, which has become particularly adapted to creating gap-free stories, predisposes us to religious thought.

    One of the arguments against evolution is that ‘natural selection’ could not have evolved cognitive skills (intelligence.) Intelligence evolved as a cognitive strategy in humans to meet the complex demands of their survival. The more difficult it is to survive the more intelligent the organism. Intelligence has to evolve, because evolution is how new traits appear and intelligence is definitely a new trait that evolved well after the basic original bacterium. Evolution operates by natural selection: traits that help an organism survive to reproductive age (and help it to produce offspring that do the same) will be in evidence in those succeeding generations. Traits that did not do this will disappear with the organisms that died before they could pass them on.

    Natural selection will leave traces behind in the structure of modern organisms, so, when scientists look for those traces they find loads of them. Natural selection operates by preserving small, favorable variations that occur naturally in any population of organisms. Over time these variations accumulate to the point that large-scale change is the result. This implies that natural selection works by modifying structures already present in the organism. It does not craft new, complex systems from scratch.

    Intelligence (abstract thinking) evolved specifically to allow our ancestors to deal with evolutionary novel problems. What modern man is learning (from birth) is what it has taken mankind to learn for millions of years. So, our intelligence is also based on the fact that we are learning what it has taken millions of years to develop in terms of knowledge.

    Our brains have gotten bigger over time, and our bodies have gotten smaller, because our brains were more important for our survival. The human brain developed more because we had to solve problems for our survival. Man needed to solve theoretical problems in order to survive. Humans had to mentally conceive of various imaginary hazards (that were possible) in order to be prepared in advance. Humans were using theoretical (highly evolved) thinking in order to survive.

    It sounds like the author of that theistic evolution book thinks the fact of a human imagination proves that there is a god. The ancient man had a very active imagination because he didn’t have much knowledge. He used mythology (fantasy) to explain things in the world that he didn’t understand. This would increase the ability to use the imagination, because man just didn’t have enough information to rationalize or explain things about the world logically. These myths were not factual or logical (they were imaginative) and this is where all of the god myths came from. Ancient man used their imaginations (myths) instead of knowledge or logic to explain certain things that were beyond their intellectual capabilities. They simply had not acquired enough knowledge to answer questions about life or the world. That is how we got our man made-up “god of the gaps.” The concept of a personal “god” may have served a practical purpose in ancient civilizations. Religion may have given an identity to groups of people, and kept them together under one leader’s control, but god myths didn’t explain anything, and they no longer serve any purpose.

  19. Moderators’ message

    A reminder that our Terms of Use do not permit the large-scale copying and pasting of material found elsewhere. A brief quotation, provided you give the source, is acceptable, as is providing a link to online material that supports your argument – provided that the link is not to your own or another user’s website/blog/YouTube channel etc, and provided you are not merely giving the link instead of arguing your position in your own words.

    A link to our Terms and Conditions can be found at the foot of each page.

    The mods

  20. RE: Theistic evolution and purpose By Bahraini

    You have presented a theory that does not provide any evidence, hypothesis, experiments or even the title of the book? The ideas of the author of the (theistic evolution) book on how we became so smart are not valid unless someone provides some evidence. I think they should come up with a testable theory that proves a “Creator” and not evolution alone is the reason for human intelligence.

    Man needed to solve theoretical problems in order to survive or mentally conceive of various imaginary hazards that were possible in order to be prepared in advance. Abstract thinking (intelligence) evolved specifically to allow our ancestors to deal with evolutionary novel problems, along with the fact that human intelligence is also based on the fact that we are learning what it has taken millions of years to develop in terms of knowledge from birth.

    It sounds like the author of that (theistic evolution) book thinks that the fact that mankind has an imagination proves that there is a god? The ancient man had a very active imagination because he didn’t have much knowledge. He used mythology (fantasy) to explain things in the world that he didn’t understand. This would increase the ability to use the imagination, because man just didn’t have enough information to rationalize or explain things about the world logically. These myths were not factual or logical (they were imaginative) and this is where all of the god myths came from. Ancient man used their imaginations (myths) instead of knowledge or logic to explain certain things that were beyond their intellectual capabilities. They simply had not acquired enough knowledge to answer questions about life or the world. That is how we got our man made-up “god of the gaps.” The concept of a personal “god” may have served a practical purpose in ancient civilizations. Religion may have given an identity to groups of people, and kept them together under one leader’s control, but god myths didn’t explain anything, and they no longer serve any purpose.

    This was not in that book about where love, sex and religion came from – these are things I know from reading things in many different sources.

  21. I think that if god wanted us to recognize and pray to him, that he wouldn’t hide his existence and expect us to take his existence on faith knowing (because he is omniscient) that our modern brains would force a lot of us to look objectively at the evidence. and he certainly wouldn’t expect us to follow an ancient book full of fantastically, unbelievable stories which contradicts itself and leads an objective onlooker to surmise that it is a faulty relic written for people who lived in the desert 6000 years ago.

  22. His argument that the best “tool” to survive is intelligence is foolish and is easily dis-proven by simply observing the natural world. If natural selection had a purpose or an end-game in mind, you would expect there to be a panoply of intelligent species on earth, not just ours. You would also expect that the ratio of non-intelligent species to the intelligent species would be very small. Neither of these trends are observed and in fact, the most successful life forms on this planet (microbes) do not even possess a rudimentary nervous system. Natural selection will favor traits in the gene pool that when possessed by a body, enable that body to leave more offspring, all of which is strictly contingent on the natural environment that one finds himself in. Intelligence is not required for survival and is not the optimal state for an organism to strive for in EVERY environment. For examples, humans are the most intelligent species on earth (let’s not flatter ourselves however) but if the environment were to suddenly change such that there were no more dry land, we would quickly find ourselves being funneled to the brink of extinction.

    And even if intelligence was a highly desirable trait, in what way does that prove that there is a god? I’m curious as to which logical pathway he took to get from “natural selection favors intelligence—->therefore, god”?

  23. I think that one of the most excellent survivors is Treponema Pallidum- it was just some centuries ago when syphilis could kill you in a couple of weeks, but recently I read an interview of some Dermatologist, who told that the longest period from getting infected to seeking help in her practice was 22 years. And the patient was still very much alive. So I think it is an excellent story, even more excellent that those of antibiotic-resistant bacteri, because here causal agent (stupid bacteria) just adopted, so that the host would live as long as possible.

  24. Bacteria are more successful than humans. We happen to be a very complex solution to the problem of staying alive, which is no more than interesting, but there are more bacteria by number, variety, total biomass and duration of existence, in each case by several orders of magnitude over humans. And they didn’t need a place in The Ark, either….

  25. No theory of evolution that does not explain the diversity of human nature across the world is worth much. The fact remains that people live to ideas and beliefs that they have acquired from their environment and upbringing. There is an inner compulsion in seeking truth that is pronounced is many individuals. Some inner psychological force is responsible for this mental disorder which is not animalistic. It makes people live to certain religious beliefs which they find very difficult to discard. Human evolution needs to explain this phenomenon. Here is my attempt at rationalising this: http://dispersalofhumanityfromhomoegaster.wordpress.com/2013/08/28/the-characteristics-of-human-evolution-through-consciousness/.

Leave a Reply