Common Sense and Reid’s Razor

by Michael Davidson

One of the problems in philosophy is how to set standards by which philosophical theories might be evaluated. Various philosophers have proposed razors, ie philosophical principles that can be used to cut away and discard other philosophical principles and ideas. Perhaps the best known are Ockham’s Razor and Hume’s Fork. Another razor is ‘common sense’. This term has unfortunately become a pejorative in some philosophical and ‘scientific’ circles along with ‘folk psychology’ which means explanations of the behaviour of people in terms of their beliefs and goals, rather than in ‘scientific’ terms such as neurophysiology. One objection to the term ‘common sense’ is that though everyone presumes to have it, it seems to be remarkably absent in others, and it lacks any agreed definition.

Another objection is that our best physics (ie quantum mechanics and relativity) “defies common sense” and since this physics describes how the world is, common sense can and should be discarded as inconsistent with reality. The astrophysicist John Barrow, for example, defines common sense as

“a description that crystallises from what is already known, and implies a certain unwillingness to admit any change, …the implication being that any deviation from it would be uncommonly senseless”.(Barrow 1988)

Similarly the biologist Lewis Wolpert contends

“that ‘natural’ thinking – ordinary day-to-day common sense – will never give an understanding about the nature of science. Scientific ideas are with rare exceptions counter-intuitive: they cannot be acquired by simple inspection of phenomena and are often outside everyday experience. Secondly, doing science requires a conscious awareness of the pitfalls of ‘natural’ thinking. For common sense is prone to error when applied to problems requiring rigorous and quantitative thinking; lay theories are highly unreliable.
. . .I would almost contend that if something fits in with common sense it almost certainly isn’t science. The reason is that the way in which the universe works is not the way in which common sense works.
. . . common sense thinking is quite unsatisfactory [for science]. It is quite different from scientific thinking lacking the necessary rigour consistency and objectivity.
. . . One of the strongest arguments for the distance between common sense and science is that the whole of science is totally irrelevant to most people’s day to day lives.” (Wolpert 1992)

This view seems to promote the alienation of science from the rest of human activity. If science is antithetical to ‘common sense’ it does not follow that because something is contrary to ‘common sense’ it must be true. In another part of the book, Wolpert states that he is ‘a common-sense realist’ ieI believe there is an external world which I share with others and which can be studied.” but holds that his philosophical position is irrelevant to his scientific activities.

In both these examples ‘common sense’ seems to mean the frequent notions that people have about the world particularly in those areas in which they have little or no experience. Appeals to common sense certainly ought to be more careful and more specific about what particular principle is held to be ‘sensible’ and ‘common’. But neither ‘frequent beliefs’ nor ‘common sense’ are a single principle.

The foremost ‘common sense’ philosopher was probably the Scottish philosopher Thomas Reid (1710 – 1796). Reid acknowledged Francis Bacon and John Locke as his predecessors. Reid’s standing as a philosopher diminished at the hands of Kant who was dismissive of common sense as

“but an appeal to the opinion of the multitude, of whose applause the philosopher is ashamed, while the popular charlatan glories and confides in it.” (Kant 1783)

The most well-known ‘common sense philosopher’ of the twentieth century was G E Moore (1873-1958), through his defence of common sense in an essay.(Moore 1925) Karl Popper also claimed that his philosophical theories did not clash with common sense nor with science (Popper 1983). Commitment to ‘common sense’ is of course no guarantee of having it.

Defining what we mean by common sense is not easy. Generally we define it by those things which are not it, for example when someone does something we consider stupid. If we look up the two words in the dictionary we find:

common: shared (as in ‘common property’); open or free to all (as in ‘common land’); frequent (as in ‘a common event’); inferior (as in ‘a common dwelling’).
sense: sensation (as in ‘sense of pain’); understanding (as in ‘it makes sense’); sound reasoning and judgement (as in ‘to speak sense’); opinion or sentiment (as in ‘the sense of the meeting’).

With four possible meanings each of ‘common’ and ‘sense’, (plus some minor meanings) we have plenty of room for misunderstanding and misrepresentation. The form of common sense that is usually dismissed as useless is ‘frequent opinions’ or ‘frequent notions’. Many frequent notions are false and misleading. That is no news. A different reading of the term ‘common sense’ is “the power of reasoning and judgement possessed by people in general and open and free to all.” Very often when this power is brought to bear on frequent notions they are seen to be the falsehoods they are. What is missing from frequent false notions is exactly this power. Obviously I do not mean to say that all mankind are capable of discourse on quantum mechanics; but I do mean to say that most people given the inclination, aptitude and application would be able to appreciate the subject. The sciences are built on this power presumed to exist for all. Not everyone can be an Einstein and trail blaze, but we assume that everyone with an inclination can follow. In the sciences, at least, there are no private lines to God.

‘Common sense’ is for reasons mentioned an unfortunate term. A possible alternative term is ‘good sense’ which perhaps escapes the connotation of “everybody knows (that which turns out not to be so)”, and perhaps sees the term more as an epistemological one than a metaphysical one. It is difficult to see how any principle can stand once we throw out good sense as a starting point.

Reid defined common sense as “that degree of judgement which is common to men with whom we can converse and transact business” (Reid 1785a) I have no quarrel with this definition. To try to avoid the unfortunate connotations of the term ‘common sense’ I refer to this as ‘Reid’s Razor’. Take a philosophical or scientific principle that is being applied to a particular situation: ask yourself whether you would be able to converse rationally and transact business with that person assuming that principle governed the situation or persons involved. If not dismiss the principle as erroneous or at least deeply suspicious. For example, suppose someone proposes that things-as-they-appear-to-be are not things-as-they-really-are. I do not think I would buy a used car from this man.

Thomas Reid (1710 – 1796)
Reid goes on to list a number of principles that he holds to be contingently true (but not necessarily true all the time) (Reid 1785b)

1) Everything of which I am conscious really exists
2) The thoughts of which I am conscious are the thoughts of a being which I call myself, my mind, my person.
3) Events that I clearly remember really did happen.
4) Our personal identity and continued existence extends as far back in time as we remember anything clearly.
5) Those things that we clearly perceive by our senses really exist and really are what we perceive them to be.
6) We have some power over our actions and over the decisions of our will.
7) The natural faculties by which we distinguish truth from error are not deceptive.
8) There is life and thought in our fellow-men with whom we converse.
9) Certain features of the face, tones of voice, and physical gestures indicate certain thoughts and dispositions of mind.
10) A certain respect should be accorded to human testimony in matters of fact, and even to human authority in matters of opinion.
11) For many outcomes that will depend on the will of man, there is a self-evident probability, greater or less according to circumstances.
12) In the phenomena of Nature, what happens will probably be like what has happened in similar circumstances.

According to Reid, anyone who doubts these principles will be incapable of rational discourse and those philosophers who profess to doubt them cannot do so sincerely and consistently. Each of these principles, if denied, can be turned back on the denier. For example, although it is not possible to justify the validity of memory (3) without reference to premises that rest on memory, to dispense with memory as usually unreliable is just not philosophically possible. Reid qualifies some of these principles as not applying in all cases, or as the assumptions that we presume to hold when we converse, which may be contradicted by subsequent experience. For instance with regard to (10) Reid believes that most men are more apt to over-rate testimony and authority than to under-rate them; which suggests to Reid that this principle retains some force even when it could be replaced by reasoning.

I endorse Reid’s principles as normally true and what we must assume to be true to engage in argument and discussion. But, as Reid acknowledges, not all may be true all the time. I thus see Reid’s principles as epistemological rather than metaphysical. Psychologists might point to such things as optical illusions, false memory, attentional blink, hallucinations and various other interesting phenomena which might throw some doubt over some of Reid’s assertions. But these are nonessential modifiers that if entertained as falsifications of these principles would lead to the collapse of all knowledge. Very few philosophers have not acknowledged that the senses can deceive us or that reason is fallible, but to say the senses consistently deceive or that reason is impotent is too big a sacrifice. That the senses can deceive and reason is fallible is good reason to be cautious in our conclusions but not a good reason to dispense with observation and reason all together. Whereas it may be true that

“we are the sort of creatures who cannot help but believe some things that are false,” and “There seems to be no guarantee that our epistemic capacities really give us access to the world,” (Jamieson 1991)

it does not follow that everything we believe is false, nor that our most cherished beliefs – 1 to 12 above – are entirely false.


Barrow J (1988) The World within the World, Oxford University Press, p54
Jamieson D (1991) Method and Moral Theory in Singer P (ed) A Companion to Ethics Blackwell p 476-487
Kant I (1783) Prolegomena to any Future Metaphysics transl J Fieser p6 available at
Moore GE (1925) A Defence of Common Sense in Muirhead JH (ed) Contemporary British Philosophy (2nd series), available at
Popper K (1983) Realism and the Aim of Science Routledge p131
Reid T (1785a) Essays on the Intellectual Powers of Man, Essay 6 Chapter 2 available at (p217)
Reid T (1785b) Essays on the Intellectual Powers of Man, Essay 6 Chapter 5 ibid p240-51
Wolpert L (1992) The Unnatural Nature of Science Faber & Faber pp xi,11,12,16,106,487

The Self: The greatest trick your mind never played

by Michael Davidson

The 23 February 2013 special issue of the New Scientist featured a series of short articles entitled “The Self: the greatest trick your mind ever played“. These provide various arguments as to why ‘the self’ – ie ‘you’ – is deluded into thinking it exists when in fact it doesn’t.the self

The first thing to note is that of the seven small articles, two are by the philosopher Jan Westerhoff and three are written or partially written by “New Scientist consultants”. Two other authors are named but their credentials are undisclosed. I will only comment here on Westerhoff’s articles.

Westerhoff briefly reviews some of the philosophical arguments that tell us that ‘the self’ is an illusion. Either ‘the self’ is like
1) a continuous thread which “runs through every single moment of our lives, providing a core and a unity for them.” or
2) it is just “the continuity of overlapping mental events” – somewhat like a rope which has no single fibre running the length of the rope but still holds together as a rope.

The argument against the first model is that what we normally consider to be ‘the self’ undergoes numerous changes through our lives – such as “being happy or sad, being able to speak Chinese, preferring cherries to strawberries, even being conscious.” The continuous self, then, is “so far removed from everything constituting us that its absence would scarcely be noticeable.”

The argument against the rope model is that there is no constant part therein that we can identify with.

Since these two models are flawed we are urged to conclude that a continuing ‘self’ is really an illusion. The simpler course is to think of better models. The fact that our moods, tastes, abilities etc change through our lives does not seem to be a great strike against a simple entity – attribute – ability model. The puzzle – if it be a puzzle – of how an entity can change its attributes and remain the same entity has come down to us from the ancient Greeks as the paradox of the ‘Ship of Theseus’. The idea is that as the various planks that make up the ship are replaced because of decay, it is possible eventually that no part of the original ship remains. Is it then the same ship? Such paradoxes are thus not confined to ‘the self’.

Westerhoff states that even if there is no continuing self perhaps there is a self in the here and now – ie the self is where all the senses come together.

But this apparency of the unity of conscious experience can be disrupted as seen in an experiment which is described but not referenced. This experiment was first reported by Kolers & von Gruneau (1). In it two coloured dots (one red, one green) are displayed on a screen in quick succession in different locations. According to the article the dot appears to move steadily between the two locations and change colour somewhere between. This immediately presents a paradox, since the apparent spot cannot change colour before it arrives at the second location. The apparency of motion caused by a succession of closely related images is called the ‘beta phenomenon’ and is the fortunate basis of the multi-billion dollar movie industry.

The colour changing illusion is not seen by everyone. I personally do not see it and psychologist Nelson Cowan (2) reports that he sees the moving object as colourless.

But this experiment is apparently seen of great significance in destroying the idea that ‘the self’ is the confluence of the senses whereby we get a whole view of the world – what Aristotle termed ‘the common sense’. There are innumerable other optical illusions which show that our perceptions are modulated by our sensory apparatus but these don’t evidently have the same significance. It is no surprise that the senses can be deceived by sufficiently unusual and specifically engineered events but this does not mean that our perceptions are always wrong. Indeed if they were not usually good enough we would have no criteria for determining when they deceive and human beings would have been winnowed by natural selection millennia ago. We usually can recognise illusions as illusions.

A third aspect of ‘the self’ which needs to be explained (away) is the apparency of conscious will, ie that we are agents – “the thinker of our thoughts and the doer of our deeds.” The empirical finding on which this argument relies is an experiment by Wegner & Wheatley in 1999 (3). Approx 50 volunteers were asked to move a cursor around a screen by controlling a mouse and stop the cursor on one of about 50 small images. The mouse was shared with an accomplice of the experimenters via an ouija board arrangement, and unbeknownst to the volunteer the accomplice was instructed to force a stop on particular objects at particular times. The volunteers were asked to stop on the same particular objects and then to rate how much they were actually involved in causing the stop (between 0% = ‘I allowed the stop to happen’ to 100% = ‘I intended to make the stop’). What was variable was the interval of time from the forced stop and the moment when the object was named to the volunteer. When the object name was presented between 1 and 5 seconds before the stop, the volunteers rated their intentions at 60%+-5% as opposed to when the word was presented 30 secs before or 1 sec afterwards (45% +-5%). The result is significant at the 5% level, though 45% and 60% indicates the participants weren’t particularly certain either way. The Westerhoff article however gives no hint of this uncertainty, implying a much more definite result than is in fact the case.

Wegner & Wheatley concluded that conscious will is only an apparency – similar to magic in that the magician presents an apparent causal sequence whilst the real sequence is something else. People do what they do not through conscious will but as the result of various genetic, unconscious, neural, cognitive, emotional, social and possibly other causes. This (according to Wegner & Wheatley) is the ‘core assumption‘ of psychological science. Evidently the conclusion follows from the assumption rather than the empirical facts.

The conditions of the experiment are such that the volunteer thinks that the experimenter’s accomplices are volunteers like himself. It is not known how he views the other person: as a competitor, a team player, a spectator etc. The times where the accomplice did not manage to force the stop on the particular object chosen at the desired time (which seemed to be between 22% and 47% for any one participant) were excluded from the analysis. So there are a number of question marks as to what this experiment means. The philosopher Eddy Nahmias (4) comments “When all is said and done, Wegner has offered no evidence or arguments against this proposal: certain brain processes have the property of being consciously represented to the agent as mental states we describe as beliefs, desires, intentions and actions (for instance, my brain is currently going through the processes which I experience as something like ‘I think this proposal makes sense’. Type out the words, ‘This proposal makes sense.’ and so on). How is it that these brain processes have these experiential properties is currently a mystery… But if these processes did not have their representational properties then they would not have the causal powers they have.” I comment further in chapter 12 of my e-book “Rethinking the Mind”.

In a separate article “When are you? – you are being tricked into thinking you live in the present” Westerhoff describes an experiment by Eagleman & Sejnowski (5). Five participants sat in front of a computer screen on which a small ring moved around a large circle at one revolution per second. When the ring was in a certain position of its trajectory (9 o’clock) a white disk was flashed at the 9’oclock position +- 7° and the subjects were asked to indicate whether the flash was above or below the ring when it was perceived. In this way an estimate of how much the flash was displaced from the perceived position of the ring at the time of the flash could be made. Each participant saw the flash when the ring was displaced by around 5°. When the direction of travel of the ring was reversed at the time of the flash the percept was displaced by a similar amount in the new direction of travel. By changing the time at which the reversal takes place upto 80 millisecs after the flash the perceived position of the flash can be manipulated. This indicates that “the percept attributed to the time of the flash is a function of the events that happen in the ~80 millisecs after the flash.”

According to Westerhoff “All this is slightly worrying if we hold on to the common-sense view that our selves are placed in the present. If the moment of time we are supposed to be inhabiting turns out to be a mere construction, the same is likely to be true of the self existing in that present.” This seems to be a drastic conclusion for the sake of 80 millisecs. High class athletes find it difficult to react to the starting gun in less than 180 millsecs but athletes are not considered to be zombies as a result. Similarly the apparent fact that our present moment is stretched over 80 millisecs does not entail that there is no ‘self’.

The whole approach seems to be an example of what Francis Bacon (1561-1626) identified as the human habit of accepting data that agrees with one’s own prejudices or those of the philosophical schools and rejecting data that disagrees. This was demonstrated in an experiment (6) in which 24 proponents and 24 opponents of capital punishment were shown the results of two studies that showed evidence for and against capital punishment as a deterrent.   Since the studies were fictional (unbeknownst to the 48 students) they could be ‘engineered’ to produce positive or negative findings from exactly equivalent protocols, and could be presented in either order to eliminate the effects of sequence.   Needless to say, the subjects felt that the studies confirming their view were more scientifically valid than those opposing.   Furthermore they were more convinced that their view was correct after reviewing both pieces of evidence than before, regardless of the order in which the two studies were viewed (p < 0.001).

This series of short articles in the New Scientist hold to a materialist philosophy as the starting point. Since materialist notions fail to find any reason why there should be a ‘self’ then the ‘self’ must be denied as an illusion or delusion. All forms of materialism have philosophical difficulties, as do all forms of non-materialism, such as dualism. What is required is a neutral approach that takes the empirical data and forms theories of limited applicability and from there predict and control phenomena in that area to gradually widen the theories.

Assuming the answer to the mind-body problem in advance (materialism) and limiting the search to only the empirical data that seems to confirm this philosophical view is not only self-confirming but anti-science.


1. Kolers PA & von Gruneau M (1976) Shaper and Colour in Apparent Motion Vision Research vol 16 p 329-335.

2. Cowan N (1995) Attention and Memory an Integrated Framework OUP p237

3. Wegner D & Wheatley T (1999) Apparent Mental Causation Source of the experience of Will American Psychologist vol 54 no 7 p 480-492 available at

4. Nahmias E(2002) When Consciousness matters Philosophical Psychology vol 15(4) p527-554

5. Eagleman DM & Sejnowski TJ (2000) Motion Integration and Postdiction in Visual Awareness Science vol 287 p2036

6. Lord CG, Ross L & Lepper MR (1979) Biased assimilation and attitude polarisation: The effects of prior theories on subsequently considered evidence Journal of Personality & Social Psychology vol 37 p2098-2109 available at

Can we really trust Scientists?

by Michael Davidson

Let us assume for the sake of argument that there is a subject or activity known as ‘science’.   Not just a bunch of separate activities grouped together because of a certain ‘family resemblance’.   What supposedly makes ‘science’ special is the ‘scientific method’.   This guarantees that the findings of ‘science’ are true.

The Royal Society  is one of the premier scientific societies in the world.   It was founded in 1660 with the motto “Nullius in verba” – “take nobody’s word for it”.   The original members credited Francis Bacon (1561-1626) with the inspiration to found their society.

Bacon’s idea of the scientific method was to proceed from repeated observations to general principles.   This process is called ‘induction’.   Induction is defined as the process whereby a premise of the form “All observed A’s are B” leads to a conclusion of the form “All A’s are B”.     Over time we can induce more and more general laws of nature.   From these laws we can then predict new facts and find out if they are true by experimental test.

Isaac Newton (1642-1727) claimed to have arrived at his laws of motion and gravitation  from the empirical observations made by  Kepler and Galileo (and his own experiments).

Unfortunately the philosopher David Hume (1711-1776) later showed that the idea of induction is flawed.   No finite number of observations such as
this object near the surface of the earth falls with acceleration g
can guarantee that
all objects near the surface of the earth fall with acceleration g“.   Aristotle (483-322BC) would have said: “some does not prove all” and would have pointed at fire and smoke which rise.

In view of this logical difficulty with induction, we can divide scientific method into two separate parts.:
a) how to get from observations to principles – the problem of discovery, and
b) how to justify the principles arrived at – the problem of justification.

The second part is relatively easy.   Once we have a principle we can point to all the observational and experimental evidence that is consistent with the principle.   But how we create theories is often considered a personal subjective process which logic does not illuminate.

William Whewell (1794-1866) coined the term ‘scientist’ in 1834.   He maintained that ‘scientists’ do not proceed by induction but
Success seems to consist in framing several tentative hypotheses and selecting the right one.”[1]
Observation and experiment are thus directed by the various alternative hypotheses, rather than being collected in some kind of magpie fashion as Bacon seemed to suggest.

A key step is the isolation and clarification of a concept:
Scientific induction is always guided by a concept which proves its worth by binding facts together in such a way to enable us to see significant generalisations that had previously escaped us.

Science thus depends on the creative process of forming concepts and hypotheses.   Since ‘scientists’ are human beings, their prejudices can skew the discovery of hypotheses.   Francis Bacon had already recognised and classified several such prejudices:
accepting data that agrees with one’s own ideas and dismissing data that does not;
jumping to conclusions too hastily;
the use of vague words;
clinging to fashionable ideas rather than subjecting them to test.

A 1979 experiment demonstrates the first prejudice.  24 proponents and 24 opponents of capital punishment were shown the results of two studies that showed evidence for and against capital punishment as a deterrent.

The studies were fictional (unbeknownst to the 48 students).   They were ‘engineered’ to produce positive or negative findings from exactly the same ‘evidence’.

Needless to say, the students felt that the studies confirming their view were more scientifically valid than those opposing.   Furthermore they were more convinced than before that their view was correct after reviewing both pieces of evidence .   This was regardless of the order in which they saw the two studies.[2]

There are well established concepts and principles in the sciences such as ‘the conservation of energy’ in physics, the ‘evolution of species’ in biology, the periodic table of the elements in chemistry, ‘uniformitarianism’ in geology and much much more besides.

But when we get to the forefront of research in any area of science there is great controversy.      The status of
‘string theory’ in physics[3];
sociobiology in biology [4];
morality in neuroscience (or vice versa) [5];
‘artificial intelligence’ in computer ‘science’[6]
and many others are topics of hot debate.
The story you get depends on which side of the debate the story teller sits.

The pronouncements of famous scientists on topics outside their sphere and much of what passes for ‘science’ in the press is more properly described as scientism.   Scientism is an exaggeration of the efficacy of science, the claim that the only knowledge is ‘scientific’ knowledge.

The only genuine claims according to this view are those that can be confirmed by the ‘scientific method’, though how this claim can be confirmed by the scientific method is not explained.   This claim gives rise to an exaggerated belief that we understand more about the world than we actually do.   Since the only knowledge is scientific, on this view, science tells us about the way the world really is (ie metaphysics).

Metaphysics is the branch of philosophy which deals with the ultimate nature of reality: “what kinds of things exist?” and “what is their nature?”   Metaphysics should be confined to inductive hypotheses from the various sciences and be described as metaphysical rather than ‘scientific’.

Scientists tend to see the world as explained by their particular science. Thus physicists see the world as entirely described by physics.   Neuroscientists see the world in terms of our brains.    Biologists see the world in terms of our evolutionary history.   And so on.   We only need to study one subject x to find that “all is x”.     “All is x” is metaphysics.

The difference between scientific and metaphysical hypotheses according to the modern philosopher Robert Almeder is that scientific hypotheses are “explicitly empirically testable”. It is possible to state detailed test conditions which would confirm or deny the hypothesis.

But philosophical hypotheses are only “implicitly empirically testable”. That is,  there might be some available data which would confirm or deny the hypothesis but nobody is currently able to specify what those data might be or how to get them.[7]

Thus if there is no conceivable way we can prove a ‘scientific’ claim then the claim is metaphysical not scientific.

Extrapolating from scientific evidence to metaphysical world views is not wrong provided we label it as ‘metaphysical’ rather than ‘scientific fact’.

Thus we have such ‘scientific facts’ as
‘mind is brain’[8],
‘there is no such thing as free will’[9],
‘concepts are nonsense.’[10]
These are aspects of the fashionable philosophical theory called ‘materialism’.

Materialism is not an essential feature of a science.   Some ‘scientists’ classify any endeavour that questions materialism  as ‘pseudo-science’.  They brand as taboo any investigation into the efficacy of such things as ‘alternative medicine’, parapsychology, spiritualism, etc.

George Orwell (1903-1950) in his celebrated essay on literary style, dated 1945[11], classified ‘science’ as a meaningless word because it has had several meanings and has been used “more or less dishonestly”.

The intervening half century or so has not crystallised the meaning at all.   The words ‘scientific’ and ‘scientist’ have  been hijacked by so many that they are now almost devoid of meaning.   They add only some kind of mystique to whatever pronouncement follows.

I am not ‘anti-science’.      I  believe in the power of the human imagination to frame hypotheses, to make tentative inductions, to predict effects and make experimental tests.   This leads us to theories whereby we can make broad predictions and control our environments through technology.   My beef is with the prevalence of sweeping ‘scientific’ pronouncements without adequate evidence.

Thus the answer to my question “Can we really trust scientists?” is  ‘sometimes’.   Here are a few criteria:

Is the scientist
a) speaking in his or her area of expertise?
b) not generalising into the realm of metaphysics?
c) steering clear of controversies within the field – or at least makes clear his or her position on such?
d) reviewing the evidence for his or her thesis?
e) speaking  in ordinary language?
f) proposing or endorsing something that is ethical?
If so there is a good chance you can trust him or her with the information.

These are criteria that do not just apply to scientists.
There are no special considerations for scientists. The physicist Richard Feynman said it more succinctly: “Science is the belief in the ignorance of experts.”[12]

An interesting and relevant blog about the misuse of statistics is



  1. Whewell W  (1841,1996) The Philosophy of the Inductive Sciences vol 2 Routledge  p467
  2. Lord CG, Ross L & Lepper MR  (1979) Biased assimilation and attitude polarisation: The effects of prior theories on subsequently considered evidence Journal of Personality & Social Psychology vol 37 p2098-2109 available at
  3. Smolin L  (2006) The Trouble With Physics: The Rise of String Theory, The Fall of a Science, and What Comes Next Houghton Miflin, Boston
  4. U Segerstrale  (2000) Defenders of the Truth: The Battle for Science in the socio-biology debate and beyond Oxford University Press
  5. Horgan J  (2010) Be wary of the righteous rationalist: We should reject Sam Harris’s claim that science can be a moral guidepost Scientific American 11 Oct 2010   available at
  6. Searle J (1980) Minds Brains and Programs Behavioural and Brain Sciences 3 p417
  7. Almeder R (1998) Harmless Naturalism: The Limits of Science and the Nature of Philosophy Open Court p166
  8. Dennett D (1991) Consciousness Explained Allen Lane p33
  9. Blakemore C  (1988) The Mind Machine BBC Books p7
  10. Watson JB  (1920) Is Thinking merely the Action Of Language Mechanisms?British Journal of Psychology, 11, 87-104.   available at
  11. Orwell G (1945) Politics and the English Language Penguin
  12. Feynman R (1969) What is Science? The Physics Teacher Vol. 7, issue 6

The Woman who changed her Brain

by Michael Davidson

Book Review
(first published in Journal of Scientific Exploration 2012 vol 26 no 3
subsequently published in EdgeScience no 12

The Woman who Changed her Brain: Unlocking the Extraordinary Potential of the Human Mind by Barbara Arrowsmith-Young. Square Peg, London 2012.ISBN 978-0-2240-9518-1 & Free Press New York 2012 ISBN 978-1-4516-0793-2. 268pp incl index. also available as a Kindle e-book ISBN 978-1-4516-0795-6.

This book describes the difficulties experienced by Barbara Arrowsmith-Young of growing up with severe learning difficulties; the means whereby she found the techniques, not to live with those difficulties, but to actually address and resolve them; and how she has brought those techniques to children and adults through her 35 Arrowsmith Schools now established in various parts of Canada and the US.

Barbara grew up in Peterborough, Ontario, where for the first 26 years of her life, she “lived in a fog”. She could make no sense of the relationship between the hour and minute hands of a clock, so could not tell the time. She could not add or subtract double digit numbers; had difficulty reading; got the wrong words for common objects; could not tell the difference between the right and left hands; was accident prone; kept getting lost and could not tie her shoelaces.

Barbara could however remember (parrot) accurately the 9:00 o’clock news and was evidently gifted with a remarkable memory and sense of determination. These abilities got her through school and university. The change came in graduate school when she happened across Alexander Luria’s 1972 classic The Man with the Shattered World: The History of a Brain Wound which described the cognitive deficits of a brain injured soldier from WWII. Barbara identified with the soldier among whose difficulties was the inability to tell the time following his brain injury. Around the same time she came across some work by Mark Rosenzweig (1968) which demonstrated that the brains of rats could physically change in response to stimulation. If it was possible for rat brains to change then maybe it was possible for human brains to change also.

She created flash cards with pictures of clocks and studied every day for up to twelve hours each day, gradually making the tasks more complex (like adding second hands and day hands) and demanding faster response. She does not say how long she worked at this but it appears to have been several months. Eventually the fog cleared, she not only could tell the time but points of logic, grammar and maths now made sense. Now she could suddenly understand, not merely parrot, the TV news programs.

Not all her difficulties were resolved by the clock exercises so she developed new cognitive exercises to address each difficulty in turn based on knowledge of the functional anatomy of the brain. These exercises are now routinely used in the Arrowsmith program.

Since individual parts of the brain are involved in multiple activities, a defect in one part may have multiple consequences. Therefore the first step is to isolate which part is causing the manifest difficulty through psychological testing. These component cognitive deficits are described on the Arrowsmith website and in the book. There is sufficient detail that it would be possible to isolate which of the 19 brain functions isolated is in deficit for a relative or acquaintance, though probably not as accurately as with the formal tests.

For example, the facility for “motor symbolic sequencing” is involved in reading, writing and speaking. People with impairments to this facility often misread texts, their handwriting is poor and copying text is slow and inaccurate. Spelling of the same word can vary from instance to instance. They often make apparently arithmetical errors but in reality they are making motor errors due to thinking the right answer but writing another. In severe cases they may have difficulty communicating ideas because they ramble and leave out much information, making it difficult for others to follow.

There are some hints also of the kind of exercises that could resolve the various difficulties but clearly attendance at one of the Arrowsmith schools is advised.

One of the exercises for the above symbolic sequencing deficit is to trace Chinese (or other foreign) characters with the right (dominant) hand whilst wearing an eye patch over the left eye. The idea is to stimulate the left supplementary motor area responsible for the hand-eye coordination. The several motor symbolic sequencing disabilities mentioned above tend to resolve without being directly addressed.

The exercises are arranged in sequence to gradiently address the difficulty. The tasks must be neither too easy nor too hard so that the student has to, and is able to, make a conscious effort to engage with the task. Once the difficulty is resolved the change is permanent.

The average student is usually enrolled for 3 to 4 years but progress is maintained through the period so if a student is unable to complete the three to four year program, they nevertheless benefit for every year they are in the program. In one study (Lancee 2005) of 79 students aged between 5 and 19 (average 11) who were assessed on 15 standard educational attainment tests for reading, writing, comprehension and arithmetic, 29 had between 1 and 7 scores below the 25th percentile, the lower end of the normal range. These students were considered to have the least severe learning difficulties. The average attainment in this group was at the 15th percentile at entry but after one year the average was at the 41st percentile. Even the 10 most severely affected students at intake (all 15 test scores below the 25th percentile) with average attainment at the 5th percentile had average attainment at the 25th percentile after 3 years. Age, gender and IQ do not evidently affect the rate of progress significantly.

It must be stressed that these cognitive exercises are not the same kind of thing as the computerized “brain training exercises” that are the current fad and evidently form the basis of a multi-million dollar industry. A six week study (Owen et al 2010) of 11,430 participants who ‘brain trained’ several times each week showed that there was no evidence that the training led to any improvement in untrained tasks or any general improvement in cognitive functioning. Improvement was observed on the specific tasks trained only. Evidence that some exercises aimed at ‘surface abilities’ over a six week period are ineffective is not evidence that some exercises aimed at specific ‘atomic abilities’ for several hours per day over several months to several years are not effective.

Cognitive learning difficulties can lead for those affected to social isolation and exploitation thus compounding the difficulties. Emotional and arousal problems that may arise through this mechanism are not addressed by the Arrowsmith program. Of course emotional and arousal problems can occur through psycho-social mechanisms in those not affected by learning difficulties. A wholly different approach to these appears to be needed.

What is interesting about the efficacy of these cognitive exercises is what they say about the philosophy of mind. Since they are based on an understanding of the correlations between brain anatomy and brain function they may seem to give physicalists no cause for concern and even vindication of their ‘mind is brain’ stance. But as we are constantly reminded ‘correlation does not prove causation’. The puzzle in philosophy of mind is how physical processes can give rise to consciousness. There have been numerous ‘solutions’ to this puzzle, including the idea that consciousness has no causative powers and influences the workings of the body (and brain) with the same power as “the steam-whistle which accompanies the work of a locomotive engine … without influence upon its machinery.”(Huxley 1912) This stance known as ‘epiphenomenalism’ is commonly held in some philosophical (Pauen, Staudaker & Walter 2006), neuroscientific (Soon et al 2008) and psychological (Wenger & Wheatley 1999) circles. It is flatly contradicted by the fact that the Arrowsmith exercises are done with conscious effort. It may not be psychokinesis but the evidence is that the brain is changed by the continued effort of a conscious mind. At least that is the simplest and most direct explanation.

The Arrowsmith program deserves to become known and applied world wide. I hope the organisation Barbara Arrowsmith-Young has put together will be able to cope with the demand and the inevitable criticism and conflict that will follow.

Arrowsmith website:
accessed 2012/06/14

Huxley TH (1912) Method and Results Macmillan : p240 available at accessed 2012/06/14

Lancee WJ (2005) Report of an Outcome Evaluation of the Arrowsmith Program for Treating Learning Disabled Students (available on the Arrowsmith website )

Owen AM, Hampshire A, Grahn JA, Stenton R, Dajani S, Burns AS, Howard RJ & Ballard CG (2010) Putting brain training to the test Nature vol 465 (7299) p775–778 available at accessed 2012/06/14

Pauen M, Staudacher A & Walter S (eds) (2006) Journal of Consciousness Studies vol 13 no 1-2

Rosenzweig MR, Love W & Bennett EL (1968) Effects of a Few Hours a Day of Enriched Experience on Brain Chemistry and Brain Weights Physiology & Behaviour vol 3 p819-825

Soon CS, Brass M, Heinze H-J & Haynes J-D (2008) Unconscious determinants of free decisions in the human brain. Nature Neuroscience vol 11, p543-545

Wegner D & T Wheatley T (1999) Apparent Mental Causation Source of the Experience of Will American Psychologist vol 54 no 7 p480-492 available at

The Logical Leap

by Michael Davidson

Book Review
(first published in Journal of Scientific Exploration 2011 vol 25 no 4)

The Logical Leap: Induction in Physics by David Harriman. New York: New American Library, 2010. 275pp, incl index. $16.00 (paperback) ISBN 978-0-451-23005-8

The so-called problem of induction has been with us since David Hume first drew attention to it in the mid 18th century. The problem is that we infer from a number of similar events laws of nature that are universal. We infer the idea of a cue ‘causing’ a billiard ball to move, by observation of many similar events of cues striking billiard balls. Therefore we suppose that the next time we strike a billiard ball with a cue that the ball will move in a similar way. But, says Hume, there is no valid chain of reasoning that can lead to that conclusion (there is no valid Aristotelian syllogism that leads from ‘some’ to ‘all’). We can introduce an axiom “the future resembles the past” or “nature is uniform in certain regards”, but by so doing we are arguing in a circle:

“all inferences from experience suppose . . . that the future will resemble the past, and that similar powers will be conjoined with similar sensible qualities. If there be any suspicion that the course of nature may change, and that the past may be no rule for the future, all experience becomes useless, and can give rise to no inference or conclusion. It is impossible therefore that any arguments from experience can prove this resemblance of the past to the future; since all these arguments are founded on the supposition of that resemblance” (Hume 1748).

This problem of being unable to get from past observations to some necessarily true
general principle is known as the “problem of induction”.

Induction is contrasted with deduction, which is moving from some true premises inevitably to true conclusions. Aristotle formulated the laws of logic which showed which kind of deductions (syllogisms) lead to correct conclusions, regardless of the actual objects to which the various premises refer. The ubiquitous example is “All A’s are B; C is A; Therefore C is B.” Thus “All men are mortal; Socrates is a Man; Therefore Socrates is mortal.” The point is that the deduction is valid whatever is substituted for A, B and C. The deduction is not necessarily true if the premises are not true: “All men are women; Socrates is a man; Therefore Socrates is a woman”. There is thus a distinction in Aristotelian logic between the validity of an argument and the truth of the conclusion. Aristotle came to his universal laws of logic by a process of induction. First he examined a great many arguments and arranged them into 192 possible forms, removing the particulars to which the arguments referred. Aristotle then isolated 14 valid syllogisms out of the 192 (later expanded to 19 out of 256) which give true conclusions if the premises are true. Although a syllogism may be valid and true it does not necessarily get you very far. Take for example the valid syllogism “no women are immortal; some people are women; therefore some people are mortal.” All the valid syllogisms have “all” or “no” in one or the other of the premises. But the only way such premises can be arrived at is by induction or by definition (as in mathematics).

Yet science proceeds from individual experiments and observations to general principles. It is to the problem of when and why the inference from ‘some’ to ‘all’ is legitimate; “in short, how can man determine which generalizations are true (correspond to reality) and which ones false (contradict reality)”; (p 7) that Harriman sets his mind in “The Logical Leap” subtitled “Induction in Physics”.

To answer the question Harriman relies on the Objectivist philosophy of Ayn Rand (1905-1982, author of the novel “Atlas Shrugged”, where she describes her philosophy in detail, other works of fiction and numerous philosophical essays). This takes for granted the validity of sense perception and causality (p9). Sense perception is our only contact with reality. From sense perception we find out what exists in the world: tables, chairs etc. “We form concepts by grasping similarities that make a group of existents stand out against a background of different existents.” (p10). The concepts formed in this way do not imply that all existents grouped into a concept are the same: their differences are quantitative. For instance, tables have different surface areas, different heights and different numbers of legs. “When we form a concept, our mental process consists in retaining the characteristics but omitting their differing measurements.”(p10)

Concepts are hierarchical. “The meaning of first-level concepts can be made clear simply by pointing to instances.” (p12) For higher level concepts we need definitions which must be empirical statements that specify the distinguishing characteristics and condense our knowledge of them. A concept however cannot be equated with its definition:

“The concept ‘temperature’ had the same meaning for Galileo and Einstein ie both men referred to the same physical property. The difference is only that Einstein knew much more about this property; he understood its relation to heat, to motion, and to the fundamental nature of matter.”(p13)

Generalizations are also hierarchical, and all generalizations ultimately depend on first level generalizations: “all generalizations – first level and higher – are statements of causal connection… there is nothing to make any generalization true except some form of causal relationship.” (p21). Thus, contrary to Hume, we perceive causation directly in the case of the cue and the billiard ball, and in the case of high level generalizations we discover causes by experiment. We do not discover causes by simply counting regularities or finding correlations.

The above is a (condensed) version of Rand’s theory of concepts. The so-called problem of induction relies on prior concepts. “Deduction takes for granted the process of conceptualization. Induction is the conceptualizing process itself in action.” (p35) The process of making higher level concepts requires thought and is therefore not infallible. In fact it is quite difficult.

As an example of correct induction, Harriman cites Benjamin Franklin’s famous experiment with a kite in a thunderstorm which showed that lightening is essentially electricity. Franklin drew on a number of concepts:

“‘electricity’, ‘discharge’, ‘conductor’, ‘insulator’, ‘Leyden jar’. These concepts were made possible by and represent a wealth of earlier knowledge (which was also discovered by means of experiment). Without this conceptual framework, as we may call it, Franklin could only have stared uncomprehendingly at sparks and shocks. Given such a framework, however, he can at once identify what he is seeing: the kite apparatus is a long conductor, and thus the electrically charged thundercloud causes [the Leyden jar to become charged]. Once Franklin can identify what he is seeing in such terms, his conclusion – the generalization – follows directly.”.(p32)

Harriman then discusses at length the progress of scientific knowledge in astronomy, physics and chemistry by the ‘greats’ such as Copernicus, Galileo, Kepler, Newton, Lavoisier, Dalton, Maxwell and Mendeleev and brings out the mechanics of valid induction, though the accounts might be construed as rather Whiggish, wherein the later theory is accepted as correct, the good guys are the ones who got the answer right and the bad guys are the ones who tried to resist the right answer.

From this survey Harriman shows when induction is valid and delineates several fallacies which make induction appear invalid:
a) Dropped context: To say Newton’s laws are falsified by the development of relativity and quantum mechanics is to drop the context. They are true in the context of the mechanics of ordinary bodies and the motion of planets, in which context the laws were validly induced. (p8)
b) Substituting a regularity for a cause: Lavoisier thought that the presence of oxygen in a chemical compound was what made the chemical acidic. This was merely a regularity in those acids he studied and was not found in hydrochloric acid (then known as muriatic acid).(p196)
c) Inadequate experimental controls: Galvani thought that the reason a frog’s leg placed on a silver plate jerks when touched by a bronze hook was because electricity was stored in the leg. Volta thought the reason was contact of the different metals and the frog was irrelevant for the production of electricity. Galvani and Volta both performed variations of the experiment which ‘proved’ their point. Davy later showed that the frog’s leg provided a salt solution vital for the operation of the silver-bronze battery. (p200)
d) ‘Cognitive fixation’: The physicist Lord Kelvin ‘refuted’ the up-and-coming science of geology on the grounds that the age of the Earth, according to the then known physics, was too young for the formation of mountains as postulated by the geologists. Kelvin could not see that the facts of geology suggested another energy source apart from gravity on which he based his calculations. (p206)
e) ‘Cognitive promiscuity’: Pons & Fleischman proclaimed they had been able to obtain the ‘cold fusion’ of deuterium atoms in a room temperature electrolysis experiment, “despite weak evidence and a context that makes the idea implausible… A mind that is open to any ‘possibility’, regardless of its relation to the total context of knowledge, is a mind detached from reality and therefore closed to knowledge.” (p207)
f) ‘Theory stealing’: accepting a theory as an instrument for research whilst not believing that the theory refers to reality. This was the situation through much of the 19th century when many chemists did not believe that atoms actually exist, whilst still using the theory to guide their research. (p220)

In the final chapter, Harriman turns his attention to quantum theory.

“As a mathematical formalism, quantum theory has been enormously successful. It makes quantitative predictions of impressive accuracy for a vast range of phenomena, providing the basis for modern chemistry, condensed matter physics, nuclear physics and optics. It also made possible some of the greatest technological innovations of the twentieth century, including computers and lasers. Yet as a fundamental theory of physics it is strangely empty… It gives a mathematical recipe for predicting the statistical behavior of particles but fails to provide causal models of subatomic processes.” (p248)

According to Harriman, the necessity of supposing that a single reality exists, that the human mind has a reasonably clear access to it, and that the scientist can explain it, has been surrendered not by reference to experimental facts (“the knowledge gained by experimental discovery of facts can never lead to the denial of knowledge and fact.”) but by the influence of post-Kantian philosophy,

“an enemy that operated behind the front lines and provided the corrupt framework used to misinterpret facts. By rejecting causality and accepting the unintelligibility of the atomic world, physicists have reduced themselves to mere calculating machines (at best) – and thus they are unable to ask further questions or to integrate their knowledge.”

Harriman does not discuss the double-slit experiment, the EPR experiments of Alain Aspect and others, the quantum Zeno effect, quantum computation and the various other puzzling phenomena in quantum physics. Harriman himself seems to be ‘theory stealing’ here in that he is willing to accept the benefits he lists from quantum theory without subscribing to the theory itself, nor addressing the really puzzling experimental facts on which the theory is based. There is no explanation of why quantum mechanics gives such precise answers whilst it does not correspond to reality.

I do not deny that modern physics is in something of a crisis. 96% of the universe as we know it consists of ‘dark matter’ and ‘dark energy’ which we have only the vaguest idea about. The two most successful theories we have: quantum mechanics and general relativity refer to completely different contexts and are deeply incompatible in those areas where perhaps they both apply (such as black holes). The effort to unify these two great theories has stimulated physicists to retreat into metaphysical speculation of great mathematical complexity (string theory) with as yet no hint of an experimental test.

In short, Harriman presents a reasonable theory of how a science can proceed by induction to true theories (provided you read ‘true’ as ‘true in context’ and not ‘absolute truth’). He shows, following Rand, that the problem of induction depends on prior concepts that had not been examined by Hume and that science is possible (contrary to the pessimistic conclusions of certain philosophers over the centuries). I am skeptical about his insistence that physics must conform to some pre-ordained form (which might be construed as ‘cognitive fixation’). As Neils Bohr said in response to Einstein’s insistence that “God does not play dice with the universe,”: “Do not tell God what to do.”

“Physics is the most universal of the natural sciences.” (p ix) and Harriman does not address the sciences such as biology, psychology, sociology which suffer from ‘physics envy’ but rely even more on statistics than quantum mechanics. It is here that his theory of induction might meet even tougher challenges.

Hume D (1748) “An Enquiry Concerning Human Understanding” Section IV part II.

A science of Mind?

by Michael Davidson

Is it possible to have a science of mind?   Is science necessarily materialistic so that we can only ever have a science of brain?   To answer this we need to understand what science is.

The English philosopher and statesman Francis Bacon (1561-1626) is sometimes credited as the “father of modern science” for his philosophical work, the “Instauratio Magna” (Latin: instauratio = to reform, to repair or renew; magna = great , hence the Great Restoration) which was only partially completed.

Bacon roundly condemned his predecessors: they have laid “down the law of nature as a thing already searched out and understood, [and] have therein done philosophy and the sciences great injury. For as they have been successful in inducing belief, so they have been effective in quenching and stopping inquiry.”

Bacon saw that the way the human mind is constituted makes rational enquiry and experiment difficult. We have a propensity to generalise too hastily. We accept data that agrees with our own ideas and dismiss data that does not. We use words that are too vague in meaning. We accept the dogmas of the various schools of philosophy without subjecting them to test.

It is time to reassert Bacon’s project, to roll back the tide of scientism that declares what is and what is not acceptable science, what can and what cannot be published on the grounds that we now know the laws of nature. This ‘scientific’ view declares that people are material objects subject to the same laws as the rest of the universe which we now thoroughly understand.  Human beings are machines.  There is no such thing as ‘free will’, it is a delusion foisted on us by electrochemical processes in the brain. But in that case how is it that we seem to have free will? Who or what is this ‘us’ that harbours such a delusion? How do electro-chemical impulses in the brain provide us with this rich perceptual world? Are we really the effect of our genes and upbringing – robots programmed to react in certain ways? Or is it the case that we really are agents, able to actually cause events?

My e-book “Rethinking the Mind” considers the evidence from multiple perspectives including the philosophy of mind, the sciences of physics, biology and neurology and the technologies of computers and psychiatry. I conclude that much of the ‘common knowledge’ in these subjects which describes human beings as physical objects whose thoughts are mere by-products of brain processes determined by the laws of physics and chemistry, is actually metaphysics masquerading as science.

A more considered approach requires a better understanding of what we mean by the word ‘science’, and an empirical approach to the phenomena of mind without insisting that the evidence should fit into some preconceived scheme.