Saturday, April 25, 2020

Logical Positivism

According to some, modern science has conquered the world. Some scientists, and some others, have been so impressed by the achievements of science that they believe that everything is a scientific problem and that all scientific problems can be solved. It is just a matter of time, effort and the application of the scientific method.

Other problems that people have, such as decisions over life and death, whether to fall in love (insofar as that might be a decision), how to bring up children, whether to read this novel or watch that television program can all, under this model, be solved by scientific means. A quick brain scan to establish which areas light up with activity when you think about your proto-beloved and you can get the go-ahead for a relationship. The reason we do not do this is that the technology is not quite there yet, and it might take a while to obtain relevant results.

That does not stop some people, of course, from arguing that more or less everything is subject to scientific control and experiment. Nothing else exists – our thoughts about our beloved are ‘nothing but’ brain activity. How we get for a bunch of jumping neurons to a conscious thought about our beloved (or whatever else, of course) is never really explained. Science is reductionist, on the whole, so we can drill down from thoughts to neurons hopping, but not the other way terribly successfully.

The ultimate in this sort of thinking was perhaps the philosophical movement known as Logical Positivism. For various reasons the proponents of this set of ideas (it was not really a single, coherent, movement) was that everything had to verifiable or it could be ruled out as legitimate discourse. The English version of this was promulgated by A. J. Ayer in Language, Truth and Logic, first published in the 1930s. The work introduced the idea of the verification principle, that a proposition is said to be verifiable in the strong sense if and only if its truth could be conclusively established in experience. In the weak sense, a proposition is verifiable if experience could render it probable. This was tremendously influential in Anglo-American philosophy.

The problem is that the verification principle rules out a lot of our normal experience and understandings. ‘Murder is wrong’ is not probable nor can it be verified by experiment – you cannot go an murder a sample of people and establish that it was wrong to do so in each and every case. The world simply does not work the way this philosophy would like it to. Logical Positivists had to resort to ideas such as emotionalism, arguing that a statement such as ‘Murder is wrong’ cannot be verified (a relief to those of us who would rather not see philosophers on the street murdering people) but is an emotional response instead. Our moral world is reduced to our emotional reactions: ‘Murder is wrong’ is at the same level as ‘I love Bach’. Surely something has gone wrong here.

There are other problems as well, of course. Intentionally, Logical Positivists had a tendency to rule that religious statements were non-sense assertions and then, by linguistic sleight of hand aver that religion was nonsense. Now, of course, some religious statements are nonsense, but no more than statements made in other walks of life such as politics or science. The removal of metaphysics, religion and morality from the realm of sense suggests that the whole agenda is a bit flawed.

The verification principle, in its bald form, is ‘no statement is true unless it is a tautology, evident from the senses or self-evident’. Thus, ‘here is a tree’ is verifiably true, as is ‘all unmarried men are bachelors’. As we have seen, ‘murder is wrong’ is not verifiable, but then nor is ‘I love you’ ‘I will meet you tomorrow at five o’clock’ or ‘God sustains the world’. None of these latter statements would usually be regarded as nonsense, however – they are intelligible, even if we cannot agree with them.

The problem is with the verification principle itself. In fact, the principle is self-stultifying. Itself it is neither a tautology, self-evident not evident from the senses. According to its own lights, then, the verification principle is nonsense, or at least, non-sense. I doubt that there are many philosophers in the world who would subscribe to it anymore, and few in the last fifty years or so who would take is terribly serious, except as an example of how philosophy can go badly wrong.

The influence of logical positivism is, however, still widespread in the education system and among some rather, perhaps, philosophically naïve scientists. To be fair, it takes a while for such problems to work their way out of a system. If the current crop of teachers were trained by people who had been trained by those who subscribed to logical positivism, perhaps we should not be surprised that it has a rather long half-life. Similarly, most scientists are philosophically naïve. While there might be late-night undergraduate discussions about the meaning of quantum mechanics, science is simply not taught with an idea of the philosophical background to it.

We therefore land up with eminent scientists making pronouncements that would not be out of place on a logical positivist’s platform. Among these might be ideas that the existence of God or the usefulness of prayer should be subject to experiment. One of two of these ideas have been tried out, of course, such as having people in hospital prayed for and seeing if they recover more quickly than others, or praying that God would strike the subject with lightening to prove He exists.  This is all rather naïve (not to say silly) but can be taken rather seriously by those who subscribe to a logical positivist or total empiricist position.

The real failure in such thought systems is not of science, or of theology or philosophy, but of individuals failing to note that all positions actually return to metaphysics, some set of underlying beliefs that cannot be justified, verified or claimed as being universally true in all times and places. We stand on thousands of years of the evolution of human thought, and we do not arrive at the ‘big questions’ without some background knowledge and understanding. If we start to assume that the place where we stand the only coherent one, then we have not just lost any argument with those who differ from us, we have rather lost our ability to be in the discussion at all.

Saturday, April 18, 2020


A particular view of the world and of science, in particular, is empiricism. In some senses it is a British phenomenon – Locke, Berkley and Hume are generally regarded as the ‘British empiricists’, and their influence does pervade the British, and plausibly, the English speaking world. That is not to say that the three agreed. Berkley rose to be a bishop, Hume was possibly an atheist, and Locke is often regarded at the forefather of Deism. Even within that, Hume regarded Berkley as a sceptic and Locke died having a Psalm read out to him. Even Hume was either too cautious or too sceptical of his own ability to discourse on a deity to be particularly clear as to his religious convictions.

Paul Avis observes (Avis, P. (2014) In Search of Authority: Anglican Theological Method from the Reformation to the Enlightenment, London, T & T Clark.) that recent historiography has attempted to understand figures who are recognised as precursors to the modern, scientific, worldview as atheists or, at least, sceptics to such a degree as their own religious beliefs are underplayed. For example, there is no evidence that Sir Francis Bacon was an atheist – he was brought up as a Puritan and never seems to have strayed far from the Church of England as founded. A thorough search of his writings can turn up ideas that might be seen as opposing Christian doctrine, but that is also true of most theologians. Expressing an idea which is opposed to orthodoxy is not, in itself, an admission of unorthodoxy, heresy or anything else. It might be being intellectually honest.

Within the world of empiricism, it is a bit hard to make the ‘leap’ to God. The empirical is based on those things which we can perceive. Hume is very clear – everything we can conceive is either based on perception (I can hear the birds singing) or memory (I hear this cheeping noise and I know that birds make that noise, so I know the birds are singing). Everything else is a product of putting these things together – perceptions and our memories of them.

There are problems here, naturally. Essentially, the danger of strict empiricism is that we start without knowledge of the world and do not seem to be able to obtain any. So we have to start from knowing something (that the world exists) which means that not everything can be a perception. Foundationalism, the idea that knowledge must start with something we can know incorrigibly, cannot be strictly correct. The mind cannot be a blank sheet on which the world is inscribed, together with our ways of connecting those impressions.

Science is, in some of its forms, a type of empiricism. There is an idea in the philosophy of science called ‘constructive empiricism’, whereby a theory is empirically adequate if what it predicts is true. Hence, we can live happily with a theory which uses the concept of an electron, so long as it predicts things which are true (say, about electric currents flowing which we can measure). We do not have to believe in the existence of electrons at all.

The problem here is that physicists, in general, do believe in the real existence of electrons. Their theories might be empirically adequate and, as we have seen, ultimately unprovable, but most physicists actually believe that there are in the universe entities which we label electrons. There is a great deal of evidence to suggest that electrons do exist as entities, and that evidence arises from different experiments and theoretical endeavours.

Electrons are, of course, very small (actually, they have no measurable radius, and are usually taken to be mathematical points). At such a small scale they behave oddly, counterintuitively. The scale of action of a single electron is so small that we cannot imagine it, imagine what is going on at that level or what an electron might see. All we can do is apply some ideas of quantum mechanics and mathematics and compare the results with what we see at the human scale. We cannot ‘understand’ an electron.

Our knowledge of what is true in the world is therefore not as great as we might like, or might be led to believe. That does not stop us, of course, from behaving as if many things are true, such as believing that it is raining at the moment, or that if I fall I shall hurt myself. We need to know a lot of things that are true in order to survive at all. Imagine how difficult life would get if we needed to convince ourselves every mealtime that it is true that we need to eat to survive. Some psychological cases along those lines exist, and they are often tragic, but fortunately, most of us will simply have something to eat because we are hungry.

There are a lot of things, therefore, tied up in what we know, what we believe to be true. Sense perceptions are some of them, a big factor, but they are not the only factor. One day I was driving to work in the dark and I say in front of me two rear lights from a van, one on the extreme left of the inside lane of the dual carriageway, one on the extreme right of the outside lane. I thought ‘that is a very wide van’. Immediately, however, the idea of a two-lane wide van was rejected by some other part of my mental apparatus and I looked again and noted the car which was blocking my sight of both the other rear lights. Perception is important but does not rule without question.

It is part of philosophical folklore history that Hume shocked Kant out of his ‘dogmatic slumbers’ into his idealism, although I cannot, for the moment, put my hands on the book that downplays Hume’s influence. Nevertheless the problem remains. Kant’s idealism does not really solve the problem, but places it within us. All we can perceive is the phenomenal and that perception is essentially the same problem as that tackled by Hume, the problem of getting from perception to our minds, and from perception to what is “out there”.

Saturday, April 11, 2020

Science and Truth

Truth, or at least knowledge, can be thought of as ideological. There is knowledge, that is, justified true beliefs that were obvious to our ancestors but are anything but to us. The position of women in society is one of them, although the historical record shows that that seems not to have been quite as robust as the (male) commentators of the time would have claimed.

There are also claims that science is ideological. After all, the ‘scientific revolution’ was a Western innovation and was dominated by males. A certain quantity of scepticism is therefore aimed at the claims of science, with suggestions that it is inherently sexist, racist and so on. I am not expert enough to comment on the sexism and racism that is (or was: let us hope that things are improving) extant in the history of science, but it does sometimes seem that those women who did achieve anything in the sciences are lauded simply by being rare.

Ideological claims about science go beyond the accusations of modern cultural suspicions. Science can start to claim hegemony overall knowledge, and at that point, it either starts to look a bit silly or becomes dangerous. An example of this is some misconceived ‘experiments’ designed to determine whether prayer (presumably to the Christian deity, but I forget the details) ‘works’. This entails a great deal of difficulty and a large number of assumptions about prayer, the deity in question and what on earth a prayer working would look like. Some things, it seems, cannot be subjected to the empirical study the natural sciences are based on.

In fact, consider a few other options. Try designing an experiment to see if your partner loves you. Can this be reduced to a set of variables which can be controlled against? I very much doubt if any such experiment could be conducted and, of course, if you did conduct such an experiment and got a positive result, you would then have to conduct another one to see if, after the experiment, they still loved you.

As another issue, consider the experiments required to determine the truth of ‘I shall meet you under the clock tomorrow at noon.’ In advance, there are few empirical activities you could undertake to establish the truth of this statement. You could, I suppose, evaluate the history of the speaker, rating them for accuracy, reliability and so on. You could enforce upon them a lie detector test. None of these would seem to be as accurate as simply believing them to be telling the truth and waiting for them to turn up tomorrow, under the clock at midday.

It is not, therefore, simply in religious behaviour that the claims of some scientists to be the sole source of knowledge start to look silly. Human relationships, on the whole, cannot be so evaluated. As can be imagined, even science itself is a product of a set of human relationships, and these are, in general, not measured. We are back to the question of ideology in science again. By assumption, and simply to get anything working at all, some stuff has to be excluded – in this case, the humanity of the observers.

The idea of modern science is that experiments can be repeated and, when that is done by a different set of people, they will get the same result. This is quite hard to achieve, due to constraints of time, money, personnel and equipment, but it can be done. Early in my career as a scientist I came up with an unexpected result and published it, without any explanation of how it came about (because I did not know) although it was supported by one set of calculations (although not by two others). Another research group did happen to have the time, equipment and interest to try it out. Doubtless, they also had a degree of scepticism about my results as well. They reported their results at a conference which I attended and confirmed them.

The example is of something which is assumed in modern science but often does not happen. As with the coherence theory of truth, if the new result coheres with the expectation often there is not much interest or confirmation. If the result defies the rest of the subject, then researchers around the world start checking up on it. Sometimes flaws are found; sometimes the new results or ideas are confirmed. That is how science develops.

Bayes’ theorem is in use here. The probability of a hypothesis given a set of evidence is regarded as the probability of the hypothesis without the evidence multiplied by the probability of the evidence being true given the hypothesis, divided by the probability of the evidence being true. The more evidence there is given the hypothesis, the bigger the probability of the hypothesis being true (it is easier to see this in the formula, and hard to type about; see


This is of course precisely what happened in the case of my observation: someone repeated the experiment and obtained the same result. The probability of the result being true was therefore increased, and the probability of the calculation which gave the same answer as my result being true was raised as a result. The result is in the literature, although so far as I know it has not been fully explained as yet.

There are, naturally, problems with Bayes’ theorem, but I do not think we need to go into them. What I have described is the normal process of science, but I dare say you have spotted a problem. We are talking in a rather loose way, about the theorems and experiments being ‘true’. The point here is that the science can never make the probability of the hypothesis given the evidence one; the hypothesis can never be said to be absolutely true. There is no proof in science; only in mathematics can things be said to be proved and even then there are problems.

Normally, this lack of proof does not matter one jot. There is sufficient experience, other evidence and coherence with other results and theory around to enable us to make reasonable judgments about what is true and what is not, even if the truth is ‘overwhelmingly probable’ rather than ‘proven’. But often that is not how the rhetoric of science works – words like ‘proven’ and ‘shown’ are bandied around in the media and some scientists fall for their own claims about the power of science.

Saturday, April 4, 2020

Coherence and Correspondence

Pontius Pilate’s question ‘What is truth?’ addressed to Jesus, of course, invokes an irony to readers of the Gospel of St John. A few chapters earlier, Jesus had told his disciples ‘I am the way, and the truth, and the light’ (John 14:6). At his trial, Pilate inquires of Jesus, the prisoner, ‘What is truth?’ The seeker asks the Truth the nature of truth.

Without getting into the complexities of how the truth could be embodied in a person, we can describe the truth in two general theoretical ways. The first is the correspondence theory and the second is coherence theory. The correspondence theory suggests that truth is not mind-dependent in any significant way. If I see a field, a field is before me. True propositions (‘I see a field’) correspond with reality (there is a field which I am looking at). There are, of course, many nuances of this theory which philosophers and others have delighted in engaging with, but for the moment we can say that the correspondence theory is a form of realism: what you see is what is there.

The coherence theory suggests that what is true coheres with other propositions. A true proposition is in agreement with many other justified true propositions. Those propositions, of course, are coherent themselves with other justified true propositions, and so on. The problem here is that all the coherent propositions might be wrong; the mental structure could be entirely coherent within itself but bear no relationship to the world.

Which of the theories is right? Well, it depends on what you mean but I suspect that, practically, both have elements of correctness in them. We do perceive and all of us believe that most of our perceptions are correct. I can perceive my cat and stroke her. I see her, feel her fur, hear her purring and so on, and these perceptions go together to make the proposition ‘this is my cat’ which I accept as true. I do not, unless I am writing like this, actually think like that. I recognise my cat (and she recognises me) and we interact. There is some correspondence of perception with the world; there is some coherence of perception with other justified truths. We do not really seem to have advanced very far.

Ideas of truth rapidly run into other, equally contested, ideas. Justification is one of them, as is belief. One idea of knowledge is that it is a justified true belief. That is, if I believe something that is both justified and true then I know something. Unfortunately, this idea was debunked by Gettier (Gettier, E. L. (1963) 'Is Justified True Belief Knowledge?', Analysis, vol. 23, no. 6, pp 121-123.) who showed that some, at least, justified true beliefs are not knowledge. Knowledge, then, is another contested concept.

These questions become rather more acute when we look at something that assumes knowledge, truth and justification. For example, an experiment in physics is built on a whole pile of other experiments, theoretical constructs and the relationship between the two. It is often said that theory is experiment laden and experiment is theory-laden, and that is true. The implications of that are far more significant than usually imagined, however.

Suppose I, as I used to, want to carry out an experiment in the spectroscopy of a plasma. This is just a jargon-ridden way of saying I want to look at the light emitted when I put a current through a low-pressure gas, helium in my case. The current causes the atoms to ionise, and the ions collapse into a thin pencil in the centre of the tube. As they have extra energy, the atoms and ions emit light at energies (frequencies) which are known from non-plasma experiments and from theoretical calculations. The shape and location of these spectral lines can be measured and this yields information about how the ions and atoms are affected by being in a plasma.

The experiment, then, rests on a large quantity of assumptions and beliefs. Atomic theory is one of them, which tells me where the spectral lines should be and also goes towards explaining the broadening and shift of them. But there are more theoretical and experimental items in the pile supporting this experiment – ideas about electrical currents and ionisation; about the detection systems; theories of how spectrometers work (the equipment used to spread the light out in wavelength so we can see the spectral lines); measurements of the calibration of the equipment; statistics about the repeatability of the results and so on.

The point here is not the details of the experiments I conducted (you have to be an enthusiast for that), but the mound of previous experiment, theory and testimony about those theories and experiments that there is. The testimony comes in the form of scientific articles that are peer-reviewed and published; in textbooks; in lectures, seminars, over coffee and by working with others in the same laboratory, learning how stuff is done. When the pile of stuff needed to understand a single experiment is considered, it starts to seem a bit remarkable that we can achieve anything like knowledge. No wonder that the claims of science often seem to be very cautious and modest. They have to be.

Truth, in a scientific context, is elusive. I cannot tell you what is true about an atom in a plasma. I can tell you something about how the light from that atom (and a large number of its colleagues) might be like, and what that may tell us about how the atoms are behaving in those conditions. I have a model, partly mathematical, partly in my head, of how these things work. But it is a model, it is not a description of how these things work. Often we forget that our scientific models are models, not descriptions of reality. Is a scientific (or any other sort of) model ‘right’?

The best a scientific model can do, really, is to predict some stuff (say the light emitted by a plasma) and we can see whether the prediction and what we measure match. Further, we can try to explain why they might not. I once received a note on an undergraduate laboratory experiment report praising me for my ability to ‘explain (away) the results’. As the foregoing suggests, I am still trying to work through the implications of that.

Contemporary Theology

What, you might well ask, is contemporary theology and why does it matter? I have been reading MacGregor, K. R., Contemporary Theology: A ...