00:00:10.640 And today it's an audio-only podcast, there's no video for this one.
00:00:14.920 It's basically about another esoteric area of philosophy, one of my more favourite papers
00:00:21.680 that David Deutsch has published over the years.
00:00:25.160 The logic of experimental tests, particularly of Everretian quantum theory, that was a 2016
00:00:36.520 David is very much the intellectual heir of Pop-Bart, so in this episode, not only am I
00:00:41.000 going to be discussing that paper with a few little embellishments of my own, but also going
00:00:47.400 back to have a look at what Pop-A said about many of the same issues, obviously Pop-A
00:00:51.960 wasn't talking about Everretian quantum theory, he didn't understand that he wasn't aware
00:00:56.400 of it, he did struggle to try and understand quantum theory himself and fail to do so.
00:01:02.760 Nonetheless, the material here about the kinds of experiments that exist in science and
00:01:08.840 how science makes progress really find their seed in Pop-A's work very early on as
00:01:15.600 well, right back to his first book, back in 1934, I think it was the logic of scientific
00:01:21.680 discovery, so we'll come back to that at some point.
00:01:24.880 So this episode is somewhat a standalone episode, but it's also going to serve as an introduction
00:01:29.400 to chapter 11, the multiverse, which is the next video and the next podcast that I'll
00:01:35.240 That's going to spread over at least three more episodes, it's going to be quite a big
00:01:38.840 one, I want to be able to explain lots of the experiments that force us to realise that
00:01:45.920 classical physics just won't cut it in order to explain what's really going on.
00:01:51.840 Now the multiverse, which does explain what's happening in these experiments that I'll
00:01:55.640 be discussing, turns out to be a testable physics theory, it's not an unfulcifiable
00:02:04.960 Even some physicists who purport to support the multiverse as the way of understanding
00:02:09.400 what happens in quantum mechanical experiments say the multiverse is unfulcifiable, which
00:02:14.200 seems to me to be a contradiction in terms, after all, if the results of those experiments
00:02:18.920 were otherwise, there'd be no reason to invoke the multiverse in the first place.
00:02:23.440 I've heard all sorts of prominent physicists go so far as to say that the whole principle
00:02:27.720 of falsificationism as explained by Popper is obsolete because the quantum multiverse exists
00:02:36.320 And because those other multiverse exists, but aren't testable, then we can jettison the
00:02:41.560 falsifiability criterion, sometimes people who follow Popper in this regard about the
00:02:47.600 falsifiability criterion, sidelined as paparazzi.
00:02:53.040 As a fan of Popper, I'm yet to come across these people myself.
00:02:56.880 You can tell people who haven't really read Popper, they are prone to say things like
00:03:01.480 Popper didn't understand, you cannot categorically refute a theory in science, or he didn't
00:03:06.320 realize that falsification isn't so straightforward.
00:03:09.640 The problem with this is that Popper wrote many, many books on this topic.
00:03:15.640 He didn't merely blog or tweet, he wrote hundreds of thousands of words basically about
00:03:19.000 critical rationalism, epistemology, as applied to everything.
00:03:22.640 He considered very many angles that people could object to falsification from.
00:03:27.280 He encountered critics in his long life and he responded to them, few stones were left unturned.
00:03:32.960 Why he elicits such casual dismissal among some remains a mystery.
00:03:37.280 Whatever the case, falsification, or another way of putting this, the experiment is a
00:03:46.240 The crucial experiment is a crucial aspect of science, and we'll be talking today about
00:03:51.280 two different kinds of experiment that do exist in science.
00:03:54.520 There's the crucial kind, the crucial test being, as David describes it, the centerpiece
00:04:01.920 Crucial experiments can be conducted that would, if the results were just so, falsify
00:04:06.080 quantum theory, or at least make it problematic.
00:04:09.640 People who try to reject falsificationism in science tend to never to grapple with this
00:04:13.840 idea of the crucial experiment that could merely make a theory problematic.
00:04:18.920 David is explained two ways the multiverse can be tested.
00:04:22.880 Firstly, against so-called collapse interpretations.
00:04:26.920 And secondly, against rival theories that purport that not everything that can happen
00:04:33.680 So I'll make some remarks about that first thing, against so-called collapse interpretations
00:04:38.520 today, but we'll basically be concentrating on the latter, that a crucial experiment would
00:04:43.560 be able to decide between the everything that can happen does happen idea, and the idea
00:04:49.640 from classical physics that basically only one thing ever does happen.
00:04:53.760 And an everything that could possibly happen actually does happen in physical reality is
00:04:58.920 another term for ever eddy and quantum theory or the multiverse.
00:05:03.800 Forcification in many ways is just a very simple idea, but for many philosophers and
00:05:07.720 scientists, it seems too difficult an idea and so they want to jettison it.
00:05:12.200 On social media, we often find people rediscovering the Duhamquine thesis, and we'll
00:05:18.960 Now the paper that David wrote in 2016, the logic of experimental tests, I think that
00:05:24.720 if you're really interested in the philosophy of science or epistemology more broadly, then
00:05:33.240 Yet it is hard going in places, and if you don't have a physics background, you might
00:05:37.640 stumble over some of the nomenclature and some of the other formalism that's in the paper.
00:05:42.600 But you can read it more or less by ignoring those few pieces of mathematical jargon
00:05:50.000 What I want to do here is try and denude the paper of some of its jargon and attempt, however
00:05:54.360 poorly, to try and reconstruct some of the arguments.
00:05:57.160 I'm going to quote somewhat from the paper today, not hugely lengthy quoting, so that
00:06:02.120 you can get a flavour of how clearly David writes about these issues.
00:06:06.760 I really do think, however, there's no substitute for reading the original paper, but
00:06:09.960 it's absolutely seminal work, and do consult the original paper as linked to on my website.
00:06:16.360 I'll have a link to that also here in the podcast.
00:06:20.040 Some of the material in the paper can, of course, be found elsewhere, particularly in David's
00:06:23.600 previous works, The Fabric of Reality, back in 1997, and The Beginning of Infinity in 2011.
00:06:28.800 However, there's much that's new in this paper, and it supplements and is supplemented
00:06:35.400 And some excellent clarifications of key points in the philosophy of science, and as one
00:06:39.400 may guess from the title, the actual role of the experiment in the sciences.
00:06:44.480 Although the central concern of the paper is a defence of the role of explanation in
00:06:47.920 science, and so an explanation both of explanation itself and the purpose of experimental
00:06:54.360 Another crucial point emphasise throughout the paper, despite David's books and comments
00:06:59.000 on the topic, is how quantum theory is fully deterministic.
00:07:04.600 Despite what passes for high school and undergraduate teachings on the subject, and what
00:07:07.520 one finds in popular books and documentaries, name and text, quantum theory is not a theory
00:07:13.000 about how the world is governed by laws that are probabilistic.
00:07:17.280 All laws that bring true objective randomness into the world.
00:07:26.960 We may not have information within our universe to know what's going to happen next.
00:07:33.560 But it's all explained by purely deterministic laws.
00:07:37.320 Everything is determined by the quantum mechanical laws of motion, in the general theory
00:07:43.000 And those laws of motion specify that what is observed to occur happens because of everything
00:07:50.920 That is to say, the laws of quantum theory predict that prior to an observation, everything
00:07:57.600 And all those occurrences come to bear upon the outcome that you do observe, indeed not
00:08:01.880 merely prior to the observation, but during and after the observation, whatever is physically
00:08:06.160 possible and can happen at those times does happen.
00:08:10.760 Necessarily an observer finds themselves only in one universe and therefore observing only
00:08:17.920 Now, to my mind, this should be no more mysterious than that observers necessarily only
00:08:22.920 ever experience a particularly instant in time as well.
00:08:26.360 They never experience many times simultaneously.
00:08:29.440 Although they know that the past must have happened and that the future will come and that
00:08:33.800 the past and future are just as real as the present, the observer can only possibly
00:08:41.720 Now another way of looking at this, and I'm taking this from an interview that David
00:08:45.600 gave, and I'll link to that interview in the notes of this podcast, is about trying to
00:08:54.000 So if we imagine a statue about which a person can walk and view from any angle, and
00:09:00.040 any instant the person might be found north of the statue, or south of it or west, or
00:09:04.080 south west, or any position in a 360 degree space around the statue, what they cannot do
00:09:09.680 is experience more than one's perspective on the statue simultaneously, but not without
00:09:15.480 I can't view it from the north and the south, say.
00:09:21.080 We must stand somewhere with respect to the statue if we wish to view it, even from above
00:09:25.440 we cannot see it all, unless and until we move, some places on the statue are hidden from
00:09:31.960 Yet we know those places that remain hidden are just as real as the places we are observing
00:09:38.920 Without those parts, the statue would perhaps topple or collapse upon itself depending
00:09:46.400 What you are able to see depends entirely on what you cannot see, if it's a real and
00:09:50.880 complete statue or not a hollowed cast, say, and we are not otherwise deceived, and this
00:09:55.160 is easy to check if we just continued to change our perspective.
00:09:59.040 So it is with quantum theory, what happens in the two slit experiment, for example, with
00:10:02.320 single particles, is that all the possible parts taken through the apparatus each time a
00:10:06.520 particle is fired at it, but we necessarily only ever see one.
00:10:11.040 When we know the other possible parts really do exist, because if you repeat the experiment
00:10:14.400 often enough, you will eventually approximate all those other parts.
00:10:17.880 Like slowly walking around the statue to gain a different perspective, David uses the
00:10:22.120 statue analogy to resolve some of the mystery about the nature of time, the subjective
00:10:26.160 consciousness of an observer must experience only the present moment and not the present
00:10:31.280 past and future simultaneously, for much the same reason that the statue viewer sees
00:10:39.280 I'm using that analogy here in an attempt to convey that if you take seriously what the
00:10:44.240 Schrödinger wave equation predicts about reality, then all physically possible events
00:10:48.520 actually occur even if you only ever experience one tiny slice of that reality at any given
00:10:54.720 The statue analogy actually shows how deep this idea of the observer having a particular
00:10:58.520 perspective on reality runs, and it must have something to do with how quantum theory,
00:11:03.320 which explains how an observer finds themselves only in every one universe, is going to
00:11:07.280 be united with the general theory of relativity, which explains how time is related to space
00:11:11.360 and that times are just specially cases of universes.
00:11:15.040 The single perspective on the greater whole that any observer necessarily has is at once
00:11:20.600 a very simple common sense and true way in which we understand the space and events
00:11:24.920 around us, but it should also be the way in which we understand better the nature of time
00:11:29.200 and the nature of so-called parallel universes, not actually parallel because they can
00:11:34.120 Now, let me turn to a little bit of quoting from the original paper that David wrote,
00:11:39.000 and I'll make some further remarks along the way.
00:11:43.560 In this paper, I shall be concerned with the part of the scientific methodology that deals
00:11:48.640 with experimental testing, but note that experimental testing is not the primary method
00:11:55.440 The overwhelming majority of theories or modifications to theories that are consistent with
00:12:00.360 existing evidence are never tested by experiment.
00:12:07.040 Experimental testing cells are primarily about explanation too.
00:12:09.880 They are precisely attempts to locate flaws in a theory by creating new explicander
00:12:14.480 of which the theory may turn out to be a bad explanation.
00:12:21.280 This is a key theme in the beginning of infinity.
00:12:23.840 The idea that science is all about experiments is a misconception, probably handed to culture
00:12:30.800 Indeed, it is the case that experiments are necessary in science, but they are far from
00:12:35.480 sufficient and although crucial, not central to the whole project, the purpose of science
00:12:44.040 David's about to come to two different types of experiments that are performed and the purpose
00:12:47.880 of those experiments, but it is vital here to notice the point.
00:12:51.880 Bad theories or silly ideas that purport to be about the physical world do not need to
00:12:58.680 That could be dismissed outright as bad explanations without it ever being tested.
00:13:02.880 This point was made in the fabric of reality with the so-called grass cure thought experiment.
00:13:07.400 If a herbalist comes to you and says that eating one kilogram of grass is a cure for
00:13:11.960 the common cold, what is the reasonable response?
00:13:15.480 Well of course it is to reject the suggestion, but on what basis?
00:13:18.800 Surely not that it is untestable because it is.
00:13:21.760 You could eat a kilogram of grass if you want to, but who would ever bother doing that?
00:13:26.000 What is truly missing from the grass cure theory is any explanation.
00:13:32.160 Unless the herbalist can give an answer that is a good explanation that explains how the
00:13:36.160 one kilogram of grass actually interacts with, let's say, viruses and destroys them or
00:13:40.120 otherwise is able to alleviate symptoms, then we know we have an explanationless theory.
00:13:46.120 And if they do, and this is key, such an explanation must be able to account for why it's
00:13:50.760 exactly one kilogram and not 0.9 kilograms or 1.1 kilograms or any other of the
00:13:57.880 Of course, I'm just noting here that many herbalists are like, do suggest something
00:14:01.920 akin to grass cures, and they do attempt explanations, but they never good explanations.
00:14:07.040 They're often nonsense, they conflict with some other actual piece of science, so if you
00:14:10.720 just think about homeopathy, for example, the idea that water remembers things that
00:14:15.240 was once diluted in it, so it remembers certain kinds of medicine once diluted in it, although
00:14:19.640 apparently it forgets the sewage that was also once in it.
00:14:23.040 This conflicts with the idea that chemicals are the agents that can actually do pharmacological
00:14:26.960 work, and not vibration or other such nonsense like that.
00:14:30.600 Okay, let me go back to David's paper and David writes, quote, scientific methodology
00:14:36.400 in turn does not, nor could it validly provide criteria for accepting a theory, conjecture,
00:14:43.360 and the correction of apparent errors and deficiencies are the only processes at work.
00:14:48.440 And just as the objective of science isn't to find evidence that justifies theories as
00:14:53.000 true or probable, so the objective of the methodology of science isn't to find rules
00:14:58.240 which, if followed, are guaranteed or likely to identify true theories as true.
00:15:05.240 There can be no such rules, a methodology is itself merely a philosophical theory.
00:15:10.240 A convention, as Popper in 1959 put it, actually proposed, that has been conjectured
00:15:15.560 to solve philosophical problems and is subject to criticism for how well or badly it seems
00:15:22.960 There cannot be an argument that certifies it as true or probable any more than there
00:15:31.600 So there David is pointing out that in the same way that we can't prove as true scientific
00:15:36.880 theories, we can't prove as true philosophical theories either.
00:15:41.480 We can't show as true this entire idea about demarcating science from non-science using
00:15:50.600 It's the wrong question, you know, how do you know that the falsification criterion
00:15:55.560 Well, that undermines the whole idea of critical rationalism, where it's all about finding
00:16:01.640 You'd need to find out what's wrong with the falsification criterion.
00:16:07.520 This is one of the most contentious pieces of philosophy that Karl Popper and David Deutscher
00:16:12.120 indeed any perperian or critical rationalist proposes about how science works.
00:16:17.520 It's poorly understood and the opposing worldview is still very much the dominant philosophy
00:16:24.560 The false idea, subscribed almost universally by scientists philosophers and laymen alike,
00:16:30.040 is that science somehow provides a way of demonstrating that certain theories are true or
00:16:34.880 close to true or probably true and moreover that the more one gathers evidence for some
00:16:41.360 theory called that theory T, then the more likely T is to be true.
00:16:46.440 What David following Popper is saying here is that there is no such process as that.
00:16:50.680 There is no method in science, no set of rules to follow that can demonstrate theories
00:16:54.280 as either true or probably true and no method in philosophy for that matter to demonstrate
00:16:59.160 that philosophical theories are true or probably true.
00:17:02.640 The whole purpose of science is not to support theories with evidence.
00:17:07.840 The truth is that science is about correcting errors in our explanations.
00:17:11.040 This is a completely different view of science to what most people have.
00:17:14.840 Now some admittedly have read a little bit of Popper or maybe some of David Deutscher
00:17:20.440 but are afraid or perhaps confused about fully taking the step to actually appreciate
00:17:25.920 Now the reason I say afraid is because it seems to me that some have the concern if
00:17:31.720 they too strongly endorse even a correct theory like this one might seem dogmatic.
00:17:38.360 So often people profess to partly support Popper that falsification is kind of a good idea
00:17:49.800 You can't mix popularian critical rationalism and falsifiability with any kind of confirmation
00:17:59.360 They don't mesh together and reading Popper really illustrates this quite well because Popper's
00:18:05.840 entire philosophy is about rejecting the idea that we can be true or probably true theories.
00:18:12.120 So there's no way in which we can simultaneously endorse Popper's idea of rejecting true
00:18:17.840 and probably true theories while simultaneously accepting the possibility of true or probably
00:18:27.000 This would simply upset the law of the excluded middle.
00:18:30.280 Things cannot both be true and not true simultaneously.
00:18:33.240 I'm just observing that there are many smart people and you prominently smart people
00:18:38.480 who struggle to grapple with the centrality of what science is even all about.
00:18:43.880 Now many science today do not want to call themselves Popurians or critical rationalists
00:18:48.080 which means they do not want to endorse the idea that science is not about supporting
00:18:51.800 theories with evidence and so they call themselves empiricists or sometimes Bayesian's
00:18:57.560 Now I've got a detailed critique of Bayesianism as a philosophy of science or as an epistemology
00:19:02.080 and you can just google my name, Brett Hall, Bayesian epistemology and it will bring up an
00:19:09.080 Just in brief however, a Bayesian is essentially someone who thinks that repeatedly observing
00:19:13.960 a phenomena allows them to build up a probability that a particular theory is true.
00:19:18.640 So they can assign a number between 0% and 100% that a given theory is true or something
00:19:23.480 So if the result of an experiment continues to come out the same way, the number, the probability
00:19:27.760 number, climbs closer and closer to 100%, but perhaps it can never reach 100%, maybe
00:19:33.320 these people are fallibleists, they don't think you can be 100% certain but you can
00:19:40.640 If you're just interested in probably true theories, perhaps 90% is okay or 95%.
00:19:45.240 Or perhaps 99.99999% at the five sigma confidence level if you understand what that means.
00:19:51.720 People in physics especially, astrophysics in particular make a big deal about the five
00:19:59.680 But one need only consider the question, what probability would a Bayesian have assigned
00:20:05.880 to Newton's theory of gravity being true at any time prior to what's having been found
00:20:12.080 Now if a scientist were actually a Bayesian in the year 1900 say, then it would seem
00:20:17.960 that every experiment ever devised to test Newton's theory of gravity always corroborated
00:20:25.720 Newton's theory correctly predicted the outcome of every well-designed and executed test
00:20:29.520 prior to it and up to and including the year 1900 and maybe a little bit later.
00:20:34.920 A Bayesian could do statistics on any prediction you like and generate some number and the
00:20:38.360 number would be pushing the ceiling of the magic 100%.
00:20:42.920 Newton's theory of gravity according to that philosophy of science would be very, very, very
00:20:48.640 close to being certainly true and yet ultimately it was shown to be false.
00:20:53.480 It was shown false by a crucial experiment on May 29, 1919 by the great physicist Arthur
00:20:58.440 Edington who measured the amount of light by which star light was bent as it passed
00:21:02.400 by the sun during a solar eclipse Newton's theory predicted one number, Einstein's another.
00:21:07.800 The amount of bending was in agreement with Einstein's theory of general relativity but
00:21:14.120 Newton's theory was then refuted so far from being very, very close to true because
00:21:18.920 of all the experiments that it had ever predicted the outcomes of up until then accurately
00:21:24.120 it was shown false by a crucial test that pitted it against arrival.
00:21:28.760 Now general relativity is in the same position that Newton's was prior to around 1900.
00:21:33.520 But it's not probably true or true or anything like that.
00:21:36.320 It contains some truth and more truth than Newton's which was closer to true than any
00:21:41.040 random guess would be but in neither case can we say that the theory is true, only that
00:21:46.640 We don't know what truth that is and it doesn't matter anyway.
00:21:49.640 The theories can be used to help us control reality around us by making predictions and
00:21:53.360 helping us to create technology to solve our problems at any time, however, to paraphrase
00:21:58.480 Thomas Huxley, the beautiful theory could be slain by some ugly fact.
00:22:02.920 Indeed, we have to expect that it will be at some point general relativity is at odds
00:22:07.600 They are mutually incompatible for reasons that I won't go into now beyond the scope of
00:22:11.480 my present piece, but in brief, the dispute might come down to a disagreement about whether
00:22:16.160 the most fundamental parts of reality consist of discrete or continuous quantities.
00:22:21.160 David has said in other places and I agree, it will be far better if we had all decided
00:22:25.040 to call scientific theories scientific misconceptions to remind ourselves of how tentative
00:22:29.680 they are and that they will one day be superseded by some better misconception, back to
00:22:37.320 Expectations apply only to some physical events, not to the truth or falsity of propositions
00:22:44.200 in general, and particularly not to scientific theories.
00:22:48.040 If we have any expectations about those, it should be that even our best and most fundamental
00:22:54.720 For example, since quantum theory in general relativity are inconsistent with each other,
00:22:58.640 we know that at least one of them is false, presumably both, and since they are required
00:23:03.280 to be testable explanations, one or both must be inadequate for some phenomena, yet
00:23:08.640 since there is currently no single rival theory with a good explanation for all the
00:23:12.640 expletander of either of them, we rightly expect their predictions to be borne out in
00:23:23.200 In other words, although we know at least one, but presumably both of our best deeper
00:23:27.760 theories of physics are false, there's no rival theory out there to replace them that can
00:23:33.600 And we must just recall that when we were a few to theory, we did not discard every single
00:23:39.280 As a rule, very much is preserved, a short example from astronomy will suffice.
00:23:44.480 Tollamy explained that the universe was geocentric, an arrangement where the Earth was
00:23:48.400 the center orbited by a smaller spheres and circles.
00:23:52.160 Copernicus theoretically did away with parts of this.
00:23:55.240 He replaced the Earth with the Sun, but he kept the circular orbits.
00:23:58.520 He kept the likewise came and replaced the circles with ellipses and then Galileo used observation
00:24:03.240 to show how the Sun centered model was superior and that there were objects orbiting Jupiter.
00:24:08.640 Newton then provided a universal physical law in mathematical form, allowing orbits to
00:24:13.680 be precisely predicted and finally Einstein showed how Newton's law was a good approximation
00:24:18.240 to a better theory of the behavior of spacetime, which explained why the paths around
00:24:24.680 But each new improvement preserved much of the past and crucially the idea, for example,
00:24:29.120 that the orbits were actually occurring, even if what was orbiting what and why changed
00:24:35.560 So, refutation of a previously good theory, whether experimental or not, does not do
00:24:40.320 away wholesale with everything that was valuable in the theory.
00:24:43.640 It preserves much, although ultimately demonstrating how the theory is fatally flawed,
00:24:47.680 and therefore ultimately false, with the proviso, as David mentions in a sectional
00:24:51.800 about to quote, that theories are never entirely logically contradicted by some experimental
00:24:57.440 observation, but this is a technical point we can return to later.
00:25:01.480 We also might observe here that people often object to the quantum multiverse idea on the
00:25:07.640 basis that, well, the next theory that replaces quantum theory and relativity might
00:25:17.040 I would find this as unlikely as the next theory of gravity, doing away with orbits, or
00:25:23.680 the next theory of genetics doing away with DNA.
00:25:27.520 More likely, that part of the theoretical apparatus will be retained.
00:25:32.800 So, DNA will be retained as in whatever the successor to genetics is going to be, or but
00:25:39.440 will be retained in whatever the successor to the best gravitational theory will be, and
00:25:45.560 what if the successor to quantum theory will be, will retain the idea of many universes?
00:25:54.360 He writes, quote, a test of a theory is an experiment whose result could make the theory
00:26:00.520 A crucial test, the centerpiece of scientific experimentation, can, on this view, take
00:26:05.960 place only when there are at least two good explanations of the same explicandum.
00:26:11.240 Good that is, apart from the fact of each other's existence.
00:26:14.120 Ideally, it is an experiment such that every possible result will make all, but one of those
00:26:19.640 theories problematic, in which case the others will have been tentatively refuted.
00:26:25.360 Now, this is an amazingly important and clear articulation of what experiments are.
00:26:32.040 Experiments test theories, but what can the results do?
00:26:34.960 Well, interestingly, if the result of an experiment conflicts with a theory, it does not
00:26:40.840 So, take, for example, the more or less frequent media hype that can surround certain
00:26:44.480 high-energy physics observations that are reported, quite often, as Einstein proved false.
00:26:50.520 Perhaps one of the more famous examples was about an experiment at the Large Hadron Collider.
00:26:55.200 You can Google this one, where neutrinos, these little particles, apparently exceeded
00:26:59.800 the speed of light, and that violated special relativity.
00:27:02.920 However, it turned out there was a cable incorrectly connected or some such.
00:27:11.800 But even if the results were true, even if the neutrinos were exceeding the speed of light,
00:27:16.440 this would not prove Einstein false, or possibly cause us to reject relativity theory.
00:27:22.200 What it would do is make relativity theory problematic.
00:27:27.080 Relativity theory would still be the best theory about how fast things can move and what
00:27:30.920 happens to things as they move relative to one another.
00:27:33.960 So a test of a theory, an experiment, even if it disagrees with the best theory going,
00:27:41.040 After all, if you reject that theory, then what theory should you use?
00:27:44.680 The second best theory is almost never a second best theory.
00:27:47.720 But even if there were, that second best theory is second best for a good set of reasons.
00:27:52.320 And if those reasons include things like, it cannot explain phenomena A, B, C, D, and
00:27:56.960 F, while the first best theory can, then there still won't be a reason to turn to that
00:28:04.560 An experimental test of a theory can result in us rejecting our best explanation.
00:28:09.040 And that is when we actually have an equally best rival theory that explains everything
00:28:14.080 our other best theory does, plus it explains the outcome of the new experimental test.
00:28:19.800 This kind of experiment is called a crucial test.
00:28:21.760 It is that rare type of test, like Eddington's observation, the bending of light, that
00:28:26.240 allows us to decide between two theories that make incompatible predictions about the outcome
00:28:32.360 But that otherwise are, until that moment, equally able to account for all other phenomena.
00:28:38.080 As it is now, of course, general relativity is able to account for far, far more than the
00:28:42.040 mere bending of starlight during eclipses over what Newton's theory can.
00:28:46.440 Newton's universal gravity, as brilliant as it is, it could get people to the moon, is
00:28:51.200 left in the distant dust by Einstein's general relativity.
00:28:55.080 Who could not only get us to the moon if we wanted to, but it also gave us GPS.
00:28:58.880 It explained neutron stars, predicted the existence of black holes, which were observed,
00:29:03.720 in much more besides, none of which Newton's theory comes close to accomplishing.
00:29:08.440 David writes in the next section, quote, the existence of a problem with a theory has little
00:29:13.880 import besides, as I said, informing research programs.
00:29:17.840 Unless both the new and the old, explicander are well explained by our rival theory.
00:29:23.040 In that case, the problem becomes grounds for considering the problematic theory tentatively
00:29:30.160 So what David's done there is de-emphasizing the supposed centrality of the experiment
00:29:36.120 to the whole project of science, scientists acknowledge creation in the form of bold explanations,
00:29:42.720 The genuinely difficult part is positing grand explanations for what's actually going on
00:29:48.240 Of course, those explanations need to be testable, but if the explanations account for
00:29:52.200 the phenomena and survive the tests, the explanation then becomes a central concern of
00:29:57.640 all of civilization who can then go about using it, making practical use of that science.
00:30:02.080 For example, to create technology, trick disease, solve other problems, and so forth.
00:30:06.720 An experiment that disagrees with some great theory just makes the theory problematic.
00:30:11.760 But if we did find some experiment that, for example, could not be explained by quantum
00:30:15.600 theory, say, or seem to refute quantum theory, that would be a problem for quantum theory,
00:30:23.320 The now problematic quantum theory would still be used to create technology, solve problems,
00:30:28.880 essentially everyone would carry on more or less as before with the respect of the theory
00:30:31.880 in regard as a genuine description of reality to some extent.
00:30:37.480 And once more, as David observed previously, and weren't about to get to as well, the
00:30:44.160 And if it's not a problem with the apparatus, it could be a problem with us not understanding
00:30:47.280 some subtlety of their theory, or it could be that the theory is genuinely not the best
00:30:51.400 theory, because someone, somewhere, has just created something better, but is yet to publish
00:30:56.960 And when they do, it will do all the quantum theory ever did, and explain the problematic
00:31:03.320 And in that case, the test that created the problem in the first place now becomes a crucial
00:31:07.640 test, as David writes, quote, in contrast, the traditional inductivist account of what
00:31:13.520 happens when experiments raise a problem is, in summary, that from an apparent unexplained
00:31:18.320 regularity, we are supposed to induce that the regularity is universal, or according to
00:31:23.440 Bayesian inductivism, to increase our credence for those theories predicting that.
00:31:28.320 While from an apparent irregularity, we are supposed not to drop the theory that had predicted
00:31:32.760 the regularity, or to reduce our credence for it.
00:31:36.000 Such procedures would neither necessitate nor yield any explanation.
00:31:44.520 Under the prevailing view of how science works.
00:31:46.920 If an experiment critically warns a theory such that it is once and for all falsified
00:31:51.320 and so liable to be rejected, then where do we jump to?
00:31:54.960 If we reject our best theory based upon an experimental refutation supposedly, and there's
00:31:59.720 no rival, the process of rejection does not provide any new explanation for us, the negation
00:32:04.920 of a theory is not a new theory, David has explained.
00:32:08.320 And David writes, quote, in any experiment designed to test a scientific theory T, the
00:32:14.120 prediction of the result expected in a T also depends upon other theories.
00:32:18.640 Background knowledge, including explanations of what the preparation of the experiment
00:32:22.600 achieves, how the apparatus works and sources of error.
00:32:26.680 Nothing about the unmet expectation dictates whether T or any of those background knowledge
00:32:33.400 Therefore there is no such thing as an experimental result logically contradicting T,
00:32:38.040 nor logically entailing a different credence for T. As David writes in a footnote in this paper,
00:32:44.240 that is known as the Juham Quine thesis, Quine 1960.
00:32:48.240 It is true and must be distinguished from the Juham Quine problem, which is the misconception
00:32:53.680 that scientific progress is therefore impossible or problematic.
00:32:58.760 Now, when I first read that back in 2016, I was so excited because it was something new
00:33:03.920 I learned about how to respond neatly to the Juham Quine thesis objections that are often
00:33:08.000 raised, if anyone gets into discussions about proper and falsification.
00:33:13.720 It's usually the first objection that people have that upon learning the headline that
00:33:19.000 pop are created, the demarcation criterion of falsification.
00:33:23.440 And that if you falsify a theory, if you're able to falsify a theory with an experimental
00:33:27.400 test, then you've got a way of distinguishing scientific type knowledge from other kinds
00:33:35.720 You can do experiments in science in order to show things are wrong.
00:33:40.000 But sometimes in philosophy, rather often, you can't.
00:33:46.280 And in fact, in some of those places, it's undesirable to even try.
00:33:49.920 Should we really try again to see if communism works?
00:33:55.440 We don't need to experimentally test if next time all those people won't be massacred,
00:34:06.120 But here, with respect that you have quine thesis, the thesis itself is correct.
00:34:10.360 But what many people assume follows from it is not.
00:34:13.760 The June quine thesis is, in my words, when an experiment is conducted, and the result disagrees
00:34:19.000 with some theory t, then it's not logically the case that t must be false.
00:34:24.120 Logically, it can always be the case that the experiment was conducted badly.
00:34:27.720 The method wasn't followed or the method was faulty in the first place.
00:34:30.800 The apparatus was faulty, or operated incorrectly, or some of the background assumptions
00:34:36.000 So, some object, using this thesis, that there's no such thing as a crucial test because
00:34:40.960 it might not be the theory t that's false, but rather it could be the experimental, the
00:34:48.760 But David's point here is that poppers philosophy of science is the correct epistemology
00:34:53.080 of how science generates knowledge, and although it can always logically be the case that
00:34:56.720 an experimental error might be at root a reason for an apparently problematic observation.
00:35:02.160 This does not have any lasting effect on how science makes progress.
00:35:05.240 Scientific progress actually happens in spite of this.
00:35:07.640 As with the faster than light neutrinos, it might have been the case that the observation
00:35:11.280 was a problem for relativity, or it might have been background assumptions in the form
00:35:16.800 That turned out to be the case, as June quine warned it always could be.
00:35:21.640 And that had no bearing on the methodology of science.
00:35:24.080 Indeed, it is the methodology of good science and uncover such problems in the first place,
00:35:27.720 and I'll ask things to keep moving in the right direction.
00:35:30.400 So just to emphasize that again, the fact that a single experimental test apparently
00:35:36.600 disagrees with your theory, so you've apparently observed something moving fast in the
00:35:41.240 And this is a problem for special relativity and general relativity.
00:35:50.120 Continue to repeat the experiment in many, many different ways, and you might just find out
00:36:04.120 The criticism was, there's neutrinos, there's particles traveling fast in the speed
00:36:08.880 of light, and this appears to be a problem for special relativity.
00:36:15.600 Let's see if that observation stands up to being repeated by many different teams around
00:36:19.640 the world, or replicated by any other group of physicists.
00:36:24.560 And if it's not, then the problem is not with relativity, the problems with your experiment.
00:36:30.160 And that has been found by the method of falsification.
00:36:34.680 We've falsified the bad observation, back to quoting David, quote, but as I have said,
00:36:43.000 an apparent failure of T's prediction is merely a problem.
00:36:45.760 So seeking an alternative to T is merely one possible approach to solving it.
00:36:50.440 And although there are always countless logically consistent options for which theory to
00:36:54.760 reject, the number of good explanations known for an explicandum is always small.
00:37:00.360 Things are going very well when there are as many as two, with perhaps the opportunity
00:37:04.240 for a crucial test, more typically it's one or zero.
00:37:07.720 For instance, when neutrinos recently appeared to violate a prediction of general relativity
00:37:11.800 by exceeding the speed of light, no good explanation involving new laws of physics was in
00:37:17.600 And the only good explanation turned out to be that a particular optical cable had been poorly
00:37:27.000 So what I'd like to say about that is that forming theories to explain things adequately
00:37:32.720 It is a highly creative process that takes understanding what seems to be happening in the
00:37:36.480 world and how to communicate the idea clearly in a language others will understand.
00:37:43.400 It can require appreciating some of the current theories and what problems there are with
00:37:49.040 In short, it requires background knowledge and then lots of imagination.
00:37:52.880 So because of some of these factors, there is a poverty of good explanations in the world,
00:37:59.800 Now here I just want to turn to a section of the paper that I won't quote, but instead
00:38:03.280 we'll put into my own words about the special case of quantum theory.
00:38:06.440 And this is really important and this is probably I guess the center of the bullseye as
00:38:10.160 to why I'm doing this podcast now, because as I say, in the next three episodes of
00:38:14.720 Topcast, especially the video version, we're going to be talking about this.
00:38:20.280 And so if you've got two explanations say, we've got explanation, capital E, and that's
00:38:33.280 Everything possible happens, technically speaking, everything physically possible happens.
00:38:37.120 So let's call that E, it's a theory about what can possibly happen.
00:38:40.800 So the everything physically possible happens theory means that A happens and B happens
00:38:50.360 Now we're going to put that up against another theory, call that explanation D.
00:38:55.480 An explanation D only predicts that one thing happens, X.
00:39:00.280 So if that one thing that D predicts happens over and over and over again when you perform
00:39:06.240 Well, the interesting thing is that E, the everything possible happens theory, is not refuted
00:39:11.240 by experiment because it also predicts that that thing should happen as well as everything
00:39:17.400 But what it cannot explain, and what E cannot explain is why only that thing should happen
00:39:24.680 while D does explain why that one thing happens and only that one thing happens.
00:39:30.040 So although experiment can't refute E in that way, the fact it's a bad explanation
00:39:38.040 Of course, if something else happens like B rather than X, then D is roundly refuted, but
00:39:45.680 The strange thing here is that even if X is observed every single time, which makes B apparently
00:39:51.040 more accurate, E might still be actually true or closer to true.
00:39:56.040 E might still be the best theory or closer to being the true theory.
00:40:00.560 It could just be a coincidence that X happens all the time, but that's a poor explanation.
00:40:06.080 And this is why poor explanations might still be more true than good explanations, as David
00:40:10.440 says at the very beginning of his paper, E could be augmented with G, where G explains
00:40:17.880 Okay, I'll quote a little bit of David here, and he writes, quote, thus, it is possible
00:40:23.720 for an explanatory theory to be refuted by experimental results that are consistent with its
00:40:28.960 In particular, the everything possible happens interpretation of quantum theory, to which it
00:40:33.480 has been claimed that ever writing in quantum theory is equivalent could be refuted in
00:40:37.240 this way, provided as always that a suitable rival theory exists in.
00:40:43.880 Therefore, the argument that ever writing in quantum theory is itself untestable fails at
00:40:48.560 its first step, and I shall show in section 8 that it is in fact much more testable
00:40:53.360 than any me everything possible happens theory.
00:40:57.600 Okay, and just my remarks on that, as David's about to explain, in a quote I'm about
00:41:02.480 to provide, but let me emphasize, the multiverse theory is testable, because it predicts
00:41:08.080 that, for example, all possible paths are taken by particles through a double slit apparatus
00:41:15.560 And that is exactly what we observe when we repeat the experiment again and again with
00:41:20.480 If the particles were instead just over and again striking the screen in one place, you
00:41:25.600 know, point x, point x, point x, point x, the electrons are going through the double slit apparatus
00:41:32.320 and just hitting the same point again and again and again, we could refute the everything
00:41:36.680 possible happens multiverse theory, because strings like that are not expected, as David
00:41:41.160 says, quote, this is because a string of repeated observations, like x, is not expected
00:41:47.800 Even though it asserts that everything, including that string, actually does happen,
00:41:55.120 Being expected is a methodological attribute of a possible result, depending, for instance,
00:42:00.240 on whether a good explanation for it exists, while happening is a factual one.
00:42:05.600 What is an issue in this paper is not whether the properties expected to happen and will
00:42:09.600 happen are consistent, but whether they can both follow from the same deterministic explanatory
00:42:14.400 theory, in this case, e, under a reasonable scientific methodology.
00:42:18.840 And I have just shown that they can end, quote, so that everyone would seem settles that
00:42:27.080 Now, I've got a few more little quotes here that I'll provide.
00:42:31.600 I just might make a remark on the further testability of multiverse theory.
00:42:37.000 Now, as far as I know, the first time it was published was in 1984 in a paper that David
00:42:43.480 wrote, and in that paper he discussed an experiment that could be performed, an interference
00:42:51.160 experiment using artificial intelligence technology.
00:42:55.360 This was also later published in a popular science book by Paul Davies, and I think it's
00:43:03.080 John Brown, Julian Brown, and they wrote a book called The Ghost in the Machine, where
00:43:08.200 they interviewed a wide variety of physicists about their understandings of quantum theory.
00:43:13.320 This is one of the first times I encountered David Deutsch, in fact.
00:43:18.040 Now in that book, David also gives a lovely popular account of the experiment that could
00:43:23.880 be performed that would refute all collapse theories, all other theories about quantum theory,
00:43:30.160 all other interpretation of quantum theory, and not refute the multiverse version of quantum
00:43:39.720 Okay, but back to this paper for now, quote from David, quote, explanation itself cannot
00:43:46.960 be defined unambiguously because, for instance, new modes of explanation can always be invented.
00:43:52.280 For example, Darwin's new mode of explanation did not involve predicting future species
00:43:57.760 Disagreeing about what is problematic or what counts as an explanation, will in general cause
00:44:01.800 scientists to embark on different research projects, of which one or both may, if they
00:44:06.320 seek it, there are no guarantees, provide evidence by both their standards that one or
00:44:13.280 There is no methodology that can validly guarantee, or promise with some probability, that
00:44:21.040 As demonstrated by countless examples of which quines is one.
00:44:25.560 But if one adopts this methodology for trying to eliminate flaws and deficiencies, then
00:44:29.280 despite the opportunities for good faith disagreements that criteria, that the criteria
00:44:39.160 I have read some criticism of David's criterion for what constitutes a good explanation.
00:44:45.000 That being that hard to vary is not well defined.
00:44:51.920 New types of explanations can always be created, not only simply new explanations, new
00:44:56.480 types of explanation, new modes of explanation.
00:44:59.000 And so a definition that is unambiguous could rule out legitimate explanations to
00:45:05.160 And so that's why hard to vary can't be constrained too much.
00:45:09.000 We're certainly after hard to vary explanations.
00:45:12.080 But if we make hard to vary too hard to vary, then we won't allow for new modes of
00:45:19.040 Going back to quoting the paper from David, quote, we have become accustomed to the idea
00:45:24.360 of physical quantities taking random values, with each possible value having a probability.
00:45:29.840 But the use of that idea in fundamental explanations in physics is inherently flawed, because
00:45:34.560 statements are signing probabilities to events, or asserting that the events are random form
00:45:38.880 with a deductively closed system from which no factual statement statements about what
00:45:43.560 happens physically about those events follows, pappin out 2002.
00:45:49.120 For instance, one cannot identify probabilities with the actual frequencies and repeated
00:45:52.640 experiments because they did not equal them in any finite number of repeats, and infinitely
00:45:58.680 In any case, no statement about frequencies in an infinite set implies anything about
00:46:02.400 a finite subset, unless it is a typical subset, but typically it's just another probabilistic
00:46:06.560 concept, not a factual one, so that would be circular.
00:46:09.400 Hence notwithstanding it, they are called probabilities.
00:46:11.640 The pie in a stochastic theory will be purely decorative, and hence the theory would remain
00:46:16.360 a mere something possible happens theory, where it not for a special methodological rule
00:46:25.640 Okay, and so there David's talking about the physical reality or otherwise of probabilities,
00:46:32.880 and he's done a wonderful lecture about this that can be found on his own website, and
00:46:38.680 I think the constructive theory website about the physics of probability, I think it's
00:46:47.400 He's quite right here about the philosophical difficulties of applying probabilities in real
00:46:55.080 For example, if we take a coin and it's a fair coin, a supposedly fair coin, and we're
00:47:00.880 flipping it, now we expect to flip it out of 100 times and expect 50 times heads and 50
00:47:07.640 It's very rare that that ever actually comes up, you get close to that, and you get
00:47:11.680 asymptotically closer to the 50-50 over time, but you never get exactly 50-50, and we wouldn't
00:47:16.800 expect in truth to get exactly 50-50, but rather something close to 50-50, you know, 47-53
00:47:25.440 or something like that, would still comport with our general understanding of probability,
00:47:30.480 but in what way does probability refer to real life?
00:47:34.400 If you're not getting exactly 50-50 every single time, you throw a fair coin 100 times,
00:47:40.640 What does it mean to say that it always comes up 50% heads and 50% tails when it doesn't?
00:47:46.440 It means that, supposedly, one view of probability is if you were to throw it in infinite
00:47:51.640 number of times, then 50% of those would be heads and 50% tails, but that's an unfulcifiable
00:48:00.640 If you want to make a claim that physical reality, then the claim has to be testable, but
00:48:04.280 you can't possibly test an infinite number of throws of the coin.
00:48:07.480 So that seems to be a problem for probability, and David deals with this in his talk, which
00:48:13.880 Okay, and just as almost as a postscript here, did Popper ever say falsification was sufficient
00:48:25.400 The logic of scientific discovery is needed 500 pages, and defends the criteria of demarcation
00:48:31.960 In that book, he also details what crucial experiments are.
00:48:35.520 He said all this back in the 1930s, and there's a free version of the logic of scientific
00:48:39.840 discovery online, you can just look for a PDF version.
00:48:44.920 And that was published in 1959, so it's got some updates from Popper himself.
00:48:49.280 David and others have said it again, and I say now, Popper understood that any purported
00:48:55.200 falsification could mean one of two things logically.
00:48:58.600 It could mean the theory as false, it would be experiment with the flawed.
00:49:03.880 We make progress by refuting theories in this way regardless.
00:49:11.400 Chapter four of the logic of scientific discovery is in fact titled falsificationism.
00:49:16.240 If it was as simple as some people seem to think, or Popper was as naive as some people
00:49:23.760 One might expect that chapter to run to a few sentences, or maybe a couple of paragraphs.
00:49:29.040 But no, Popper spends pages 57 through to 73 defending his thesis against all manner
00:49:37.240 The whole point is that he's epistemology, his philosophy of science is not summed up by those
00:49:45.960 Force of occasion is but a part of the greater whole.
00:49:51.640 What did it mean for Edington's experiment to refute Newton, but not Einstein?
00:49:56.120 Was Einstein considered true now, and Newton false?
00:50:04.680 One could well spend many episodes of a podcast like this doing a little more than discussing
00:50:07.880 Popper's epistemology is explained in the logic of scientific discovery.
00:50:11.160 Perhaps one day I will, for he seems to me to be such an underrated genius.
00:50:16.880 That so many claim to have read, and yet it seems to me, have misunderstood entirely.
00:50:22.880 It is as if those 16 pages about falsificationism in the logic of scientific discovery were
00:50:28.360 only 16 words, and that the rest of the chapter didn't exist, much less the rest of
00:50:32.880 the book, and much less all of these other books and dozens of academic papers, journal articles
00:50:36.800 and lectures, but it continues to be painted as naive, or not anticipating aspects of science
00:50:44.840 Those who try to explain his ideas more fully than the caricature that often passes for
00:50:49.400 popularizing of Popper are often ridiculed as the paparazzi I've heard recently.
00:50:55.120 That kind of reaction against Popper isn't entirely unique in philosophy, but it is almost
00:50:58.920 rather unique too philosophy or not completely, because physics suffers from this as well.
00:51:04.520 Many physicists when you talk to them can tell funny stories of emails received from someone
00:51:08.120 or other who claims to have, for example, proven Einstein wrong, perhaps with an algebraic
00:51:13.120 Such people who claim to have proven Einstein wrong really go to the trouble of trying
00:51:18.800 They look at the mathematics and refuse to believe that their common sense notion could
00:51:24.040 Galilean relativity they think must somehow be at base true, so they try their hand at
00:51:30.400 But they've engaged only with the Lorentz transformation, for example.
00:51:33.640 The very basics of special relativity, they prove somehow the speed of light is not constant.
00:51:38.800 Physicists know the feeling of dealing with these people, and they chuckle with each other
00:51:41.960 about such stories, or from the next inventor who sent them an idea for a perpetual motion
00:51:49.040 These people haven't actually read much of relativity or about the conservation of energy.
00:51:54.280 They've read perhaps a popular account or picked up a high school text and learned enough to
00:52:02.240 To those physicists, I say, that cranky engineer has a counterpart in philosophy.
00:52:07.320 They are the people who've read the popular account.
00:52:10.000 It happens with many prolific writers who solve deep problems, because the problem is deep,
00:52:14.200 and the solution often subtle, it can be tempting to shoot off a blog post or an email
00:52:17.320 or a tweet about how Einstein was wrong that relativity meant the speed of light is constant
00:52:21.760 or that time slows down the greater one's velocity is.
00:52:24.960 It's a tempting prospect for someone new to the field, or a casual reader of the field.
00:52:29.520 It's so tempting, it might even cause someone to write a blog post about how Popple
00:52:32.600 was wrong about falsification, and those that have read beyond the popularing headlines
00:52:36.840 are terribly naive about how science actually works.
00:52:40.320 So let me leave this episode with some words directly from Popper himself.
00:52:44.360 I'm going to read from unended quests, an intellectual autobiography, on page 42.
00:52:50.160 Popper writes there, that quote, my main idea in 1919 was this, if somebody proposed
00:52:56.800 a scientific theory, he should answer, as Einstein did, the question, under what conditions
00:53:05.360 In other words, what conceivable facts would I accept as reputations or falsifications
00:53:12.640 I'm skipping a little any right, any rights, he says, I still uphold this, but when a little
00:53:19.560 later I tentatively introduce the idea of falsifiability, or testability, or a futability
00:53:24.640 of a theory as a criterion of demarcation, I very soon found that every theory can be immunised.
00:53:31.720 This excellent term is due to Hans Albert, against criticism.
00:53:35.480 If we allow such immunisation, then every theory becomes unfulsifiable, thus we must
00:53:40.600 exclude at least some immunisations, so I just pause there, end quote.
00:53:46.960 In 1919, he is already considering objections to the falsification criterion, the people
00:53:55.880 today who claim that falsification is too simple an idea in the philosophy of science,
00:54:05.640 and a tribute and moreover attribute that position to Popper, haven't read Popper, given
00:54:12.840 that he considers these so-called immunisations, given that he considers ways in which the
00:54:17.880 falsification criterion can itself be problematic, and not as straightforward as a naive
00:54:24.080 falsificationist might think, so I'll continue to read Popper.
00:54:29.280 On the other hand, I also realised that we must not exclude all immunisations, not
00:54:34.360 even all which introduced ad hoc auxiliary hypotheses.
00:54:38.760 For example, the observed motion of Uranus might have been regarded as a falsification
00:54:43.520 of Newton's theory, instead the auxiliary hypothesis of an outer planet was introduced
00:54:51.200 This turned out to be fortunate, for the auxiliary hypothesis, is a testable one, even
00:54:55.560 if difficult to test, and it stood up to tests successfully.
00:54:59.760 All this shows, not only that some degree of dogmatism is fruitful, even in science,
00:55:04.880 but also that logically speaking falsifiably, or testability, cannot be regarded as a very
00:55:12.360 Later, in my logic to Foshang, the logic of scientific discovery, I dealt with this problem
00:55:18.360 I introduced degrees of testability, and these turned out to be closely related to degrees
00:55:23.680 of content, and surprisingly fertile, increase of content became the criterion for whether
00:55:28.520 we should or should not, tentatively adopt an auxiliary hypothesis.
00:55:33.360 In spite of the fact that all this was clearly stated in the logic of scientific discovery
00:55:37.160 of 934, a number of legends were propagated about my views.
00:55:42.560 First, that I had introduced falsifiability as a meaning criterion rather than as a criterion
00:55:47.880 Secondly, that I had not seen that immunisation was always possible, and had therefore
00:55:52.760 overlooked that since all theories could be rescued from falsification, none could simply
00:55:59.520 In other words, mine results were, in these legends, turned into reasons for rejecting
00:56:06.080 And I'll just make this personal reflection here on this idea that it's a very simple concept
00:56:13.320 that Poppa pointed out that the criterion of demarcation is not a criterion of meaning.
00:56:20.360 So although he was saying that this separates science from non-science, that the ability
00:56:25.400 to do an experiment demarcates the scientific enterprise from other kinds of knowledge, it's
00:56:32.920 not saying that nothing else has any meaning, or isn't useful, quite the contrary.
00:56:37.520 After all, Poppa was very interested in political philosophy, political science, political
00:56:47.880 He didn't think that philosophy was meaningless, that's why he was spending most of his
00:56:51.960 Those things are important, so when people talk about, let's say, multiverse theories
00:56:58.040 that are not the quantum multiverse theory, these cosmological multiverse theories, theory
00:57:04.720 where I would call it the megaverse, the idea that there are other universes out there
00:57:09.240 that have different physical laws, this is a very different kind of multiverse to the
00:57:14.680 multiverse that quantum theory forces us to understand the world through.
00:57:21.120 These are the megaverse theories where there might be universes out there with different
00:57:27.280 There are some physicists who are very upset about the fact that these might be ruled out
00:57:33.600 I would say, well, they're not testable, there's no testable prediction.
00:57:37.080 But there are scientists, there are physicists who say, well, this is a problem for the
00:57:41.320 demarcation criteria, and this is a problem for falsification, because we should be able
00:57:49.480 If you don't understand the problem, what they're upset by is that we're going to regard
00:57:54.840 such a theory, a theory of other universes with different physical laws as metaphysical,
00:58:00.040 and that somehow that is, in a way, lessening that theory, no, it's not.
00:58:03.920 You can still go on and do your mathematics and do your physics of these alternate theories
00:58:17.240 Some people might be interested in the work of cosmologists Luke Barnes, he's from Australia,
00:58:23.360 and one of his projects is actually to look at the question of fine-tuning, and I think
00:58:28.720 There are other physicists who do this kind of thing, are the cosmologists who do this
00:58:33.400 They use supercomputers and simulations of universes with different laws of physics,
00:58:41.480 So, to a certain extent, they're kind of testable, let's see what happens in such a universe
00:58:46.240 where you've got different physical laws, and they do this for the purposes of fine-tuning.
00:58:50.480 Are any of those universes that they simulate able to support complex chemistry, life, and so on?
00:58:58.600 Whatever the case, it's no insult to call a particular theory or idea metaphysical.
00:59:08.800 It's scientism, rank scientism, to insist that if your theory cannot be tested by experiment,
00:59:15.920 that it nonetheless should be regarded as science, then you've got a bias.
00:59:21.720 You think that scientific knowledge is in some way superior to, better than certain other
00:59:26.360 kinds of knowledge which might be very legitimate.
00:59:41.840 There's no experiment that I can do to test whether or not I'm dreaming right now or not.
00:59:47.960 Maybe when I go to sleep at night and I have a dream, I'm dreaming within a dream.
00:59:58.600 My claim that all of that is nonsense, that we are not dreaming, we're not in a simulation.
1:00:11.120 My theory that all of that is quite correct that none of this is true, that in fact reality
1:00:20.840 That metaphysical theory is just as important as any scientific theory and I'm willing
1:00:25.880 to defend that metaphysical theory and it's no insult to call it metaphysical.
1:00:30.560 It's no insult to call a certain theory, a moral theory or a mathematical theory.
1:00:39.600 Now pseudo-science is an insult, but I wouldn't regard ideas about other universes with
1:00:46.120 different physical laws as being pseudo-science.
1:00:51.480 It could be fun, philosophically interesting.
1:00:54.520 You don't have to call it science and importantly you don't have to go throwing away
1:00:58.480 the criterion of falsifiability because there's one very esoteric area of theoretical metaphysical
1:01:07.080 cosmology that you happen to enjoy doing and exploring and thinking about.
1:01:13.320 It's only ever, and I'll just end on this, it's only ever the theoretical physicists
1:01:18.320 that have a problem with the falsification criterion.
1:01:26.760 The pharmacologists don't get into these debates.
1:01:29.360 It's only the theoretical physicists that get upset at pop-up and that should be very, very
1:01:36.280 It's because they operate right at the very margins of what science can do, and that's
1:01:43.000 They need to be pushing those boundaries, but they have to recognize when things are
1:01:48.040 testable and when things aren't testable because if they're not testable, then their
1:01:51.600 ideas can't be handed over to the managers at a large Hadron Collider or to the people
1:01:59.600 There's no observation that can ever show that any of their ideas are wrong.
1:02:05.680 If they can't, well, you're doing metaphysics.
1:02:07.520 It could be interesting, it could be entertaining, it could even inform research projects
1:02:11.360 in real science, but it's not science, and it's no big deal.
1:02:15.480 Anyway, there we have it in pop-a-zone words that he wasn't an eye of falsificationists.
1:02:21.280 He did understand it all, he understood the objections, he spoke with scientists, including
1:02:26.880 He spent his life defending that thesis, and if you take it seriously and really investigate
1:02:31.640 it, and think of all the ways, it, critical rationalism, might be false, and then read
1:02:36.920 what he said in his own words, you just might be convinced he was right.
1:02:40.840 Rather than convinced he was mistaken by a headline in a brief article that mangles what
1:02:54.160 If you're getting value out of these podcasts on my YouTube videos or website, why not
1:02:59.200 I've now got a Patreon account at Brett R. Hall, all one word, so that's Brett R. R.
1:03:05.280 for Robert Hall, all one word, or if you got on my website, www.bredhall.org, there's
1:03:11.200 a donate button now on my front page, if you'd like to make a small one-off donation.
1:03:15.600 Thanks for any support, as I'm trying to devote more time to this endeavour, bye bye.
