## Measurement is theory-laden part 3

In my two previous posts in this series I pointed out that measurement is theory laden: you need an explanation of what is happening to bring about the results. Without such an explanation you can’t work out what the results of a measurement mean.

One example where I think naive ideas about measurement have caused problems is in quantum mechanics. Many physicists seem to think that when you do a measurement the measurement has to reveal a complete picture of the state of the system being measured and otherwise it just doesn’t count. So if I see my toothbrush sitting in a plastic tumbler on my right then that measurement has the outcome it does because that’s where the toothbrush is and that’s all there is to it. In quantum mechanics measurement just doesn’t work that way.

According to quantum mechanics, there are multiple versions of the toothbrush and of everything else. Those multiple versions form layers that are approximately dynamically isolated from one another – they act like parallel universes. The whole of physical reality, which includes those parallel universes, but also has richer structure, is called the multiverse. A lot of physicists seem to think that they don’t actually see multiple versions of the brush, only one version exists and quantum mechanics must be modified to take account of this. However, quantum mechanics accounts for the fact that I only see one version of the brush without eliminating the other versions. What happens is that when I see the brush different versions of the brush produce different versions of me and those different versions of me can’t interact with one another directly. So there is no conflict between the existence of multiple versions of the brush and the fact that I only ever see one version of the brush.

The next thing physicists often say when they hear this explanation is that if I can only ever see one version of the toothbrush then the existence of the multiverse makes no difference to anything. One problem with this idea is single particle interference. That is, we can do experiments in which a single particle behaves as if there are multiple versions of it going along all of the possible paths through an experiment and those different versions interact with one another but we only ever see one of them at the end of the experiment. Are we supposed to think that all the versions we didn’t see just vanish at the end of the experiment, even when quantum mechanics implies that they don’t?

There are also experiments with macroscopic systems that can’t be explained without the multiverse, such as the EPR experiment. In one version of the EPR experiment, two photons are produced by the same source at the same time and head in different directions. Let’s call one of the photons photon A and the other photon B. A photon has a property called polarisation that has some similarities to angular momentum. In particular we can measure the polarisation along different directions. We measure the polarisation along a particular direction with a filter that only lets through photons polarised in that direction. For each photon, regardless of the direction in which we measure the polarisation the probability of it going through the filter is 50%. If we measure the polarisations of A and B along the same direction then we find that they match. If we measure the polarisations along different directions we find that they don’t match with a probability that depends on the angle between the directions in which we measure the polarisations. So whether the polarisations are later found to match or not depends on whether two detectors happen to have the same setting. We can put the detectors far enough apart so that no signal can travel at or below the speed of light from one to the other during the detection process. Some physicists have decided that this means the photons influence one another by some faster than light means during the detection process. Since the probability of any given measurement result on a single photon doesn’t depend on what happens to the other photon, there is no way to use this supposed link to send messages but nevertheless many physicists seem to think the link exists. This leads to a lot of confusion about how quantum mechanics can be consistent with relativity. This confusion is entirely unnecessary because the EPR experiment can be explained without any nonlocality.

The two photons are generated in the same process at the start of the experiment t = 1 and so the multiversal description of photon A at t=1 depends on the multiversal description of photon B at t=1. After they part the photons fly apart and evolve independently of one another. They then get measured. This, too, is an entirely local process with no funny business involving photons magically influencing one another. I’ll start by discussing photon A: everything I say about photon A applies to photon B with the photons labels switched around. What happens is this: the multiversal description of the measuring device for photon A comes to depend on the multiversal description of photon A. Since the multiversal description of photon A depends on that of photon B at t = 1, the multiversal description of the measuring device for photon A also depends on the multiversal description of photon B at t=1. Exactly what information about photon B is transmitted by photon A to the measuring device depends on what happens to photon A between the t=1 and when the measurement process is over. Now regardless of exactly what polarisation observable we choose to measure in 50% of the universes the photon goes through and in 50% it doesn’t. However, the multiverse doesn’t just consist of parallel universes and some of the multiversal information contained in photon A, including the information it contains about photon B, isn’t revealed by the measurement on photon A alone, i.e. – it isn’t reflected in the way the multiverse locally differentiates into non-interacting parallel universes. What happens instead is that hidden information is transmitted to the measuring device and then to other systems that interact with the measuring device and at some point in the future the information from photon A is transmitted to some system that contains information from measurements on photon B and the measuring results from photons A and B become correlated due to the hidden multiversal information the two photons contained about one another. The precise pattern of the correlation depends on what multiversal information was transmitted by each photon to the measuring devices and so depends on what happened to them between t=1 and when they were measured.

For more technical detail see Information Flow in Entangled Quantum Systems and Does Quantum Nonlocality Exist? Bell’s Theorem and the Many-Worlds Interpretation.

What is needed to understand measurement in quantum mechanics is a more subtle idea about the role measurement plays in our understanding of the world. A measurement is an interaction whose results are relevant to whether we should accept or reject a theory. This doesn’t require that there is only one version of me after the measurement. A theory should be judged by whether it is a good explanation and whether it successfully predicts the results of experiments, not by whether it matches a naive and parochial intuition about how measurement should work.

## Nicholas Dykes has not replied to my criticism

Nicholas Dykes claims that  he has not replied to my criticism. I have criticised his non-reply reply.

## Measurement is theory-laden part 2

In my previous post in this series I discussed the idea that all measurement is theory laden and gave an example of a bad explanation of a measurement. In this post, I will give a good example, from the special theory of relativity. The point is to illustrate  that a good explanation consists of taking an idea seriously and working out its consequences, not of sweeping apparently strange implications under the rug. Doing that is an error since either those new implications are false and your idea is a dud or they are true and you have discovered something new and important. You can’t find out which of those two possibilities is true without working out the consequences of the idea.

First, two definitions that will be relevant. An frame of reference is a set of physical systems used to measure the motion of other systems. An inertial reference frame (IRF) is a frame of reference in which objects that do not suffer some external force move in straight lines. Empty space far away from any masses is a good approximation to an inertial frame. If you measure everything relative to your car while it is accelerating that won’t be a good approximation to an inertial frame because you will see things accelerating when no forces act on them.

Special relativity uses two assumptions.

(1) All IRFs are the same with respect to the laws of physics. For example, if two people use different IRFs, they will both see that objects obey conservation of momentum.

(2) The speed of light in empty space has the same value in all IRFs, denoted by c.

The second assumption looks a bit strange. If you were to get in your car and drive down the road, the cars coming in the opposite direction would be moving at a different velocity relative to you if you speed up or slow down. If you’re driving at 30mph with respect to the pavement and the chap driving in the opposite direction is also travelling at 30mph then you will see him coming at you at 60mph. But you can consistently work out the consequences of these assumptions and that’s part of what matters when it comes to doing experimental tests. (It is not the only thing that matters since some consistent and well worked out ideas don’t have empirically testable consequences.)

I will illustrate two consequences of these assumptions to illustrate what I’m talking about. The consequences in question are that if an object is moving at constant velocity (moving at a constant speed and in a constant direction) with respect to an IRF will act as if it is shorter along the direction in which you are moving than in an IRF in which it isn’t moving and any clocks attached to that object will run slower. This happens in such a way as to make measurements of the speed of light come out the same in both IRFs.

Suppose that you have a clock X that is at rest in an IRF S. This clock consists of two mirrors A and B, a distance L apart with a pulse of light bouncing between them. Each time the light pulse bounces off one of the mirrors it causes a clock attached to mirror A to tick. In the frame S the time T between ticks is 2L/c.

Now suppose there is another IRF S‘ that is moving at a speed v with respect to S at a right angle to the pulse of light bouncing between the mirrors:

The distance between the mirrors in S isn’t going to change because that distance is at right angles to the direction in which the clock is moving. The time it takes the clock to tick in S‘ is T‘. The light takes T‘/2 to hit the mirror B in S‘ and during that time the mirror has moved vT‘/2. The light then takes another T‘/2 to hit the first mirror again at position C. So using Pythagoras theorem the total distance the light travels in S‘ is

$AB + BC = 2\sqrt{L^2+(vT'/2)^2}$.

The total distance travelled by the light pulse must be cT‘ because the speed of light doesn’t change between the two frames, so

$cT' = 2\sqrt{L^2+(vT'/2)^2}$

and a bit of rearrangement gives:

$T' = \frac{2L}{\sqrt{c^2-v^2}}$.

Since L = cT/2 we can write

$T' = \frac{T}{\sqrt{1-v^2/c^2}}$

Now,

$1 > \sqrt{1-v^2/c^2}$

because v < c so the amount of time it takes for the clock to tick increases.

Now suppose that we consider another frame S” moving  at speed parallel to the direction in which the light travels in the clock:

Since the far end of the clock is moving away from the light pulse it has to travel farther than the length of the clock in S” to get to the mirror at the far end of the clock:

$L'' + vt'' = ct''$.

When the light pulse is travelling back from the far end of the clock to where it started, it travels a shorter distance:

$L'' - vu'' = cu''$.

The total time is

$T'' = u'' + v'' = \frac{2L''c}{c^2-v^2}=\frac{2L''/c}{1-v^2/c^2}$.

The time measured in S‘ and S” will be the same so:

$T'' = \frac{T}{\sqrt{1-v^2/c^2}}$

$L'' = L\sqrt{1-v^2/c^2}$

and so moving objects will act as if they are shorter.

On the scales of speed and distance we use in everyday life these effects are very small, but they can be measured for particles travelling near the speed of light and they have been found.

Followers of Karl Popper say that measurement is theory-laden. This means that every time you do a measurement you are making assumptions about how the measurement works. This implies that the idea of our knowledge being derived from measurement makes no sense since knowledge is required for measurement.

However, this is often left a bit abstract, so I thought I would provide an example in which you can be led astray by bad ideas about measurement.

Isaac Newton, despite making great contributions to our understanding of how the world worked, also came up with some confused ideas about absolute space and time. I will illustrate these ideas with quotes from an English translation of Newton’s scholium on absolute space and time.

First, Newton states that he thinks motion can’t just be relative motion:

Only I must observe, that the common people conceive those quantities under no other notions but from the relation they bear to sensible objects. And thence arise certain prejudices, for the removing of which it will be convenient to distinguish them into absolute and relative, true and apparent, mathematical and common.

Newton clarifies:

Absolute space, in its own nature, without relation to anything external, remains always similar and immovable. Relative space is some movable dimension or measure of the absolute spaces; which our senses determine by its position to bodies; and which is commonly taken for immovable space; such is the dimension of a subterraneous, an aerial, or celestial space, determined by its position in respect of the earth. Absolute and relative space are the same in figure and magnitude; but they do not remain always numerically the same. For if the earth, for instance, moves, a space of our air, which relatively and in respect of the earth remains always the same, will at one time be one part of the absolute space into which the air passes; at another time it will be another part of the same, and so, absolutely understood, it will be continually changed…

Absolute motion is the translation of a body from one absolute place into another; and relative motion, the translation from one relative place into another. Thus in a ship under sail, the relative place of a body is that part of the ship which the body possesses; or that part of the cavity which the body fills, and which therefore moves together with the ship: and relative rest is the continuance of the body in the same part of the ship, or of its cavity. But real, absolute rest, is the continuance of the body in the same part of that immovable space, in which the ship itself, its cavity, and all that it contains, is moved. Wherefore, if the earth is really at rest, the body, which relatively rests in the ship, will really and absolutely move with the same velocity which the ship has on the earth. But if the earth also moves, the true and absolute motion of the body will arise, partly from the true motion of the earth, in immovable space, partly from the relative motion of the ship on the earth; and if the body moves also relatively in the ship, its true motion will arise, partly from the true motion of the earth, in immovable space, and partly from the relative motions as well of the ship on the earth, as of the body in the ship; and from these relative motions will arise the relative motion of the body on the earth. As if that part of the earth, where the ship is, was truly moved towards the east, with a velocity of 10010 parts; while the ship itself, with a fresh gale, and full sails, is carried towards the west, with a velocity expressed by 10 of those parts; but a sailor walks in the ship towards the east, with 1 part of the said velocity; then the sailor will be moved truly in immovable space towards the east, with a velocity of 10001 parts, and relatively on the earth towards the west, with a velocity of 9 of those parts.

Newton also thought that it was possible to measure this absolute motion:

It is indeed a matter of great difficulty to discover, and effectually to distinguish, the true motions of particular bodies from the apparent; because the parts of that immovable space, in which those motions are performed, do by no means come under the obser- vation of our senses. Yet the thing is not altogether desperate; for we have some arguments to guide us, partly from the apparent motions, which are the differences of the true motions; partly from the forces, which are the causes and effects of the true motions. For instance, if two globes, kept at a given distance one from the other by means of a cord that connects them, were revolved about their common center of gravity, we might, from the tension of the cord, discover the endeavor of the globes to recede from the axis of their motion, and from thence we might compute the quantity of their circular motions. And then if any equal forces should be impressed at once on the alternate faces of the globes to augment or diminish their circular motions, from the increase or decrease of the tension of the cord, we might infer the increment or decrement of their motions; and thence would be found on what faces those forces ought to be impressed, that the motions of the globes might be most augmented; that is, we might discover their hindmost faces, or those which, in the circular motion, do follow. But the faces which follow being known, and consequently the opposite ones that precede, we should likewise know the determination of their motions. And thus we might find both the quantity and the determination of this circular motion, even in an immense vacuum, where there was nothing external or sensible with which the globes could be compared. But now, if in that space some remote bodies were placed that kept always a given position one to another, as the fixed stars do in our regions, we could not indeed determine from the relative translation of the globes among those bodies, whether the motion did belong to the globes or to the bodies. But if we observed the cord, and found that its tension was that very tension which the motions of the globes required, we might conclude the motion to be in the globes, and the bodies to be at rest; and then, lastly, from the translation of the globes among the bodies, we should find the determination of their motions. But how we are to obtain the true motions from their causes, effects, and apparent differences, and the converse, shall be explained more at large in the following treatise. For to this end it was that I composed it.

So Newton imagines an experiment involving two globes in empty space connected by a cord undergoing circular motion with respect to absolute space. The tension in the cord between the spheres increases if the globes move faster with respect to absolute space. So by measuring the tension in the cord you can tell how fast the globes are moving with respect to absolute space.

There a few problems with this proposal. First, the real universe isn’t like that, it actually has other stuff in it. Second, if there was such a universe, nobody would be able to measure the tension in the cord because there would be nobody around to measure it. Third, the globes are accelerating so at most this experiment would refute the idea that accelerated motion is motion relative to other bodies.

Newton also describes another experiment that he actually did and sounds a lot more plausible:

The effects which distinguish absolute from relative motion are, the forces of receding from the axis of circular motion. For there are no such forces in a circular motion purely relative, but in a true and absolute circular motion, they are greater or less, according to the quantity of the motion. If a vessel, hung by a long cord, is so often turned about that the cord is strongly twisted, then filled with water, and held at rest together with the water; thereupon, by the sudden action of another force, it is whirled about the contrary way, and while the cord is untwisting itself, the vessel continues for some time in this motion; the surface of the water will at first be plain, as before the vessel began to move; but after that, the vessel, by gradually communicating its motion to the water, will make it begin sensibly to revolve, and recede by little and little from the middle, and ascend to the sides of the vessel, forming itself into a concave figure (as I have experienced), and the swifter the motion becomes, the higher will the water rise, till at last, performing its revolutions in the same times with the vessel, it becomes relatively at rest in it. This ascent of the water shows its endeavor to recede from the axis of its motion; and the true and absolute circular motion of the water, which is here directly contrary to the relative, becomes known, and may be measured by this endeavor. At first, when the relative motion of the water in the vessel was greatest, it produced no endeavor to recede from the axis; the water showed no tendency to the circumference, nor any ascent towards the sides of the vessel, but remained of a plain surface, and therefore its true circular motion had not yet begun. But afterwards, when the relative motion of the water had decreased, the ascent thereof to-wards the sides of the vessel proved its endeavor to recede from the axis; and this endeavor showed the real circular motion of the water continually increasing, till it had acquired its greatest quantity, when the water rested relatively in the vessel. And therefore this endeavor does not depend upon any translation of the water in respect of the ambient bodies, nor can true circular motion be defined by such translation.

But this experiment only refutes the idea that the force on the water is determined by its motion relative to the objects that immediately surround it.

The fact that the water rises up the side of the bucket has nothing to do with absolute space and time. Rather, the water rises up the bucket because it is accelerating with respect to the gravitational field. Newton didn’t find that explanation, Einstein did that. Newton wasn’t looking for a good explanation because he thought he had already found it and proved it by doing measurements.

One moral of this story is that you should be critical of the explanations behind measurements.

## Against Censorship

Censorship is a bad idea. It is the use of force or confiscation of property or money or threats thereof to stop the expression of an idea.

Censorship is a bad idea regardless of the content of the idea for a couple of reasons.

If the idea is bad, by censoring it you prevent people who know better from answering it. This, too, prevents the improvement of ideas.

Sometimes a person will think an idea is bad even though it is good. If you censor such an idea you prevent the improvement of ideas. There is no infallible way to distinguish when you are right about an idea being bad from when you’re wrong, so this is always possible.

Traditionally, there have been many objections to free speech.

First, there is the question of whether you can shout fire in the crowded theatre when there is no fire and you’re not an actor on stage. If you shout fire in a theatre then you are doing a wrong to the people who came to watch the play, and possibly also to the theatre owner. What you are saying is not the problem, the wrong that you are doing in that context is the problem.

Second, shouldn’t people be able to control the content of their blog or YouTube account? Should they not be able to prevent you from posting comments that they dislike? Yes, they should but that’s not censorship. You can start your own blog or YouTube channel or whatever. And in any case, like the theatre owner the blog or channel owner has no obligation to use his property to support your speech. If you feel bad about this that’s your responsibility, not his.

Third, what if somebody is inciting people to violence, should we not censor him? In this case, the problem isn’t the ideas the speaker is expressing, rather he is participating in a criminal conspiracy to commit assault or murder or something like that. If the police get a tip that somebody is planning an armed robbery and raid the robbers’ hideout and stop them from making further plans, they are not interested in stopping the robbers’ speech per se, but the robbery.

Recently, the British government has proposed a plan to make internet service providers require people to block porn websites unless their customer asks them not to.

Some people have said this is a bad idea, but many of them have given the wrong argument. They say: “We agree that it is laudable to deny children (under 18s) access to porn, but this is a bad way to do it.” These people are wrong, it is not at all laudable to deny children access to porn.

“But people under 18 can’t deal with porn because they don’t have the appropriate context to deal with it,” I hear you cry. This is puzzling. Whatever the appropriate interpretation of porn might be if the child can look for porn when he’s interested in it, that will give parents an opportunity to help the child the appropriate interpretation.

The people who use the “context” excuse for censorship may not understand how porn should be interpreted. They say things like: “porn should be used as a way for people in loving relationships to spice up their sex.” Many people in romantic relationships and marriages end up suffering, so at minimum there is something wrong with the way people enact such relationships. So given that people are bad at relationships perhaps they should question the idea that they’re right about all of the issues concerned, including how to use porn.

“But people under 18 can’t understand porn,” the critic objects. If a child looks at porn and doesn’t have any understanding of what he’s seeing at all then he’ll get bored and go do something else.

But what if more teenagers get pregnant as a result of watching porn? People under the age of 18 can find out about sex in ways other than looking at porn. People under 18 found out about sex even before the internet was invented. Also, people often use porn for masturbation so why would more porn lead to more teen pregnancy?

But porn degrades women doesn’t it? If that is true, that is not just a problem for people under 18 and so can’t be a reason for preventing them specifically from getting access to porn. And in any case, the stuff women do in porn is also done by men and transexuals and midgets. While it might be a good idea to have debates about porn, we should have an open debate featuring serious arguments both for and against porn.

I think an unstated reason for the opposition to people under 18 watching porn is precisely that some of them might enjoy it. They should be working hard in school and becoming badminton champions and stuff like that. In other words, people under 18 should be doing what other people want them to do, not using their own judgement. It is disgraceful that the same adults who often chide children for not using their initiative are so keen to deprive them of opportunities to exercise their own judgement about what they should think. Anybody who wants a more rational world should be appalled by the British government’s attempt at thought control.

## Nicholas Maxwell’s bad moral philosophy

Nicholas Maxwell seems to like to think of himself as a great moral thinker, but actually he is has no good insights and seems to want to set himself up as a Platonic philosopher king.

Let’s start with his vision of one supposed problems in current affairs. He talks about a “long-standing problem of the rapid growth of the world’s population” (p. 4 of this paper). In other words, more people = badness. The truth is that high birth rates happen in dirt poor places that have bad institutions such as oppressive and corrupt governments, poor protection of property rights and that sort of thing. (Matt Ridley’s book The Rational Optimist discusses this particular issue well but I don’t endorse it in general.) It is quite revealing that he claims this is a matter of population. He doesn’t see every person as a potential creative problem solver who could make the world a better place in all sorts of major or minor ways. Rather he sees their existence as problematic and acts as an apologist for their oppressors by not even mentioning the existence of said oppression.

On reading a summary of his political agenda it becomes clearer that Maxwell is even worse than this disgraceful stance makes him sound:

Natural science needs to create committees, in the public eye, and manned by scientists and non-scientists alike, concerned to highlight and discuss failures of the priorities of research to respond to the interests of those whose needs are the greatest – the poor of the earth – as a result of the inevitable tendency of research priorities to reflect the interests of those who pay for science, and the interests of scientists themselves.

This is terribly muddled. First, science can’t reflect both what the poor currently want, what scientists currently want and what the rich currently want. For example, many poor people want to use fossil fuels and Maxwell thinks this will cause some sort of catastrophe as a result of global warming. What would be needed is a serious discussion of the political economy of current scientific institutions. Maxwell apparently has no interest in this since he doesn’t discuss it.

Rather, he wants to create a world academic government and a world government:

The world’s universities need to include a virtual world government which seeks to do what an actual elected world government ought to do, if it existed. The virtual world government would also have the task of working out how an actual democratically elected world government might be created.

Democratic institutions are problematic enough in a single country where politicians can be relatively more accountable without engaging in the pretence that such an institution can work for a world government. There is also a lot of disagreement on basic issues like whether it’s a good idea to murder Jews in the world (to judge by propaganda put out by the Palestinian Authority) never mind on complex issues like global warming. Maxwell apparently has nothing to say about any of these problems.

Maxwell is not wise or insightful. He is apparently totally oblivious to many of the most serious problems facing the world and of serious problems in his own worldview.

Nicholas Maxwell has promoted bad epistemology. As an example of this I will use his paper Popper, Kuhn, Lakatos and Aim-Oriented Empiricism.

Maxwell criticises Popper by saying he doesn’t take account of the use of metaphysical assumptions in science. Maxwell claims that science assumes that the real laws of science are unified and not ad hoc – let’s call this the unification principle. Popper, Maxwell claims, does not build this into his epistemology. As a result Popper’s epistemological claims are not justified. Popper has criticised justification and Maxwell doesn’t answer those criticisms so why does he keep going on about justification? Justification is not a minor theme, Maxwell bangs on about it incessantly. He doesn’t explain in what sense he is using the term or why anybody should care in the light of Popper’s refutation of the ideal of justification.

Maxwell claims that his unification principle is substantive and problematic because it constrains the laws of physics. But he provides no examples where it produces problems and so he solves no problems.

Maxwell claims that falsificationism does not account for the fact that scientists look for unified theories because it only justifies unification insofar as it is testable. But in The Logic of Scientific Discovery Popper discusses looking for universal theories at length in chapter III. This includes a discussion of universal terms and so on that explains that the whole of language except for proper names refers to things that are the same everywhere: water boils at 100 celsius at atmospheric pressure in containers of the right shape and so on.

He also explains why theories should not be ad hoc and Maxwell doesn’t really discuss this in detail. He provides a single example in which he claims that there is an ad hoc theory that Popper wouldn’t discard. But he doesn’t discuss how Popper’s prohibitions against ad hoc theories explained in chapter IV of LScD fail to exclude it. It is not good enough that a theory should just make correct and unambiguous predictions where it has been tested it has to to this in all the situations where it could be tested in principle. I doubt that there are any ad hoc propsosals that would satisfy this test. It’s hard enough to come up with any theory that matches reality never mind an ad hoc one.

For example, you couldn’t just say, as many physicists do, that quantum mechanics applies only to microscopic objects. You would have to specify the exact situations where it fails to apply and what happens in the transition from the regime where it does and the regime where it does not. They often apply the theory of decoherence to do this and then claim it shows that quantum mechanics doesn’t apply to macroscopic objects despite the fact that it is a consequence of quantum mechanics and so can hardly imply that quantum mechanics is false. Quantum mechanics actually applies to macroscopic objects too.

Maxwell also claims to synthesise the ideas of Popper, Kuhn and Lakatos. This is impossible because Popper refuted the claims of Kuhn and Lakatos: see Popper’s chapter in Criticism and the Growth of KnowledgeRealism and the Aim of Science and Popper’s discussion of Lakatos in Philosophy of Karl Popper. Kuhn and Lakatos both claimed that Popper thought it was possible to prove a theory wrong and that refutation played very little role in the history of science. Popper never claimed that it is possible to prove a theory wrong and pointed out that all refutations are conjecture from starting in LScD Chapter IV. Rather a refutation is treated like any other conjecture and can be conjecturally refuted. Popper also provided many historical instances in which theories have been discarded in the light of experimental evidence against them. To claim to mix a bunch of bad, refuted ideas with Popper’s ideas without refuting Popper’s criticisms is to mix philosophical food and philosophical  poison.

There may be some work to do on why the real laws of science allow the existence of criticism and why they seem to be comprehensible, matters that have discussed by David Deutsch in The Fabric of Reality, The Beginning of Infinity and his paper on constructor theory. Maxwell doesn’t shed any light on these problems.

Maxwell’s paper is full of bad arguments. In the next post I will refute Maxwell’s bad moral ideas.

UPDATE In this paper, Maxwell provides an example of a supposedly successful ad hoc theory: the standard laws of physics hold until a particular time like 8pm tonight after which gold spheres of mass greater than 1000 tons less than 1000 miles apart obey an Gm1m2/d^4 law rather than inverse square. This is outrageously ad hoc by Popper’s standards and is very problematic in the light of existing ideas about the laws of physics. Quite aside from anything else he doesn’t explain how to do relativistic corrections.