Do electrons 'really' exist?
                         ____________________________

                              Azam Mashhadi 
                     Department of Educational Studies
                           University of Oxford, 
            15 Norham Gardens, Oxford OX2 6PY, United Kingdom 

                    azam.mashhadi@edstud.ox.ac.uk

                       (received: April 8, 1997)
 
Abstract
_________

	The concept of electrons has become so widely used that in everyday 
discourse they are usually given the same ontological status as chairs. 
However electrons are 'theoretical entites', and an individual's answer to the 
question of whether they 'really exist' is ultimately a reflection of the 
individual's philosophy of science.
 
I.  Introduction
_________________ 

	The history of science has many explanatory concepts that have been 
proposed to account for the observable features of things, such as white, 
light and cool. Such explanatory concepts have often associated with them 
hidden or unseen entities. As the philosopher of science William Wallace 
(1979: 56) expresses it:
 
	...the problem arises whether these entities are mere fictions 
	created by the mind, or whether they exist, or at least have 
	counterparts that exist, outside the mind. For instance, to 
	explain why some objects of experience are hotter than others, 
	it was early hypothesized that the hotter objects might 
	contain more of an invisible substance known as phlogiston....
	[Later] it was further proposed that heat might be caused by 
	the motion of the minute particles of which material substances 
	are composed, called molecules. [1]
 
II. Theory-independent observations?
____________________________________

	Hapgood:     So you did. It's crazy. 
	Kerner (unmoved):    Oh, yes...but compared to the electron 
		it is banal. Frankly, compared to the electron 
		everything is banal. And the photon and the proton 
		and the neutron...Yelizaveta, when things get very 
		small they get truly crazy, and you don't know how 
		small things can be, you think you know but you don't 
		know. 
			Tom Stoppard (1988: 35), Hapgood   [2]
 
	The question of whether or not electrons 'really' exist, involves a 
question not just about electrons but also about whether it is possible to 
make an observational claim that is not theory-dependent or theory-laden. Can 
it be argued that in addition to, say, having a negative charge and a very 
small mass, electrons are objects that are 'out there in the external world'? 
It is possible to stand back and consider the claims of the 'electron game' 
(i.e. its methods, predictive success etc.). The question then arises on what 
basis could it be decided what the theory of electron is about, other than 
being about electrons? Hanson (1972)[3] and Thomas Kuhn (1970) both argue that 
it is not possible to do so:
 
	...there is, I think, no theory-independent way to reconstruct 
	phrases like "really there"; the notion of a match between the 
	ontology of a theory and its "real" counterpart in nature now 
	seems to me to be illusive in principle." 
			Kuhn (1970: 206)  [4]
 
III.  The reality of electrons
______________________________

	The electron is an extraordinarily useful concept in the explanation 
of electromagnetic phenomenal. Robert Millikan thought of the electron as a 
discrete corpuscle of unitary electric charge, whose action in the famous oil 
drop experiment designed to measure the charge on the electron could actually 
be seen. Millikan (1950: 80) in his Autobiography  remarks: 

	He who has seen that experiment and hundreds of investigators 
	have observed it, [has] in effect SEEN the electron ....But the 
	electron itself, which man has measured ...is neither an 
	uncertainty nor a hypothesis. IT IS A NEW EXPERIMENTAL FACT 
	that this generation in which we live has for the first time 
	seen, but which anyone who wills may henceforth see. [5] 

Gerald Holton (1978: 28) points out that the use of the beautiful 'Millikan oil 
drop experiment' ,which is now routinely part of physics courses, in the 
classroom needs to be viewed with caution:
 
	Such class activities, however, are really only pedagogic 
	exercises to bolster belief in the electron, rather than serious 
	tests of belief. Even so, it is quite difficult to obtain "good data." 
	According to one instructor's recent analysis of class experience: 
	"In spite of the improvements in the Millikan oil-drop apparatus...
	the experiment remains perhaps the most frustrating of all the 
	exercises in the undergraduate laboratory." [6] 

Wallace (1979: 59) points out that the electron is regarded by most scientists 
as having an extra-mental existence.
 
IV.  The status of theoretical entities
_______________________________________

	The basic question to physicists and philosophers is whether particles 
such as atoms, photons and electrons have the ontological status of epicycles 
and phlogiston, or whether they exist extramentally in a way similar to that 
of such everyday objects as chairs. There is considerable debate in the 
literature on this central question. John Dewey, for instance, proposed a 
distinction between the statements 'theoretical entities are real' and 
'theoretical entities exist' (Morgenbesser, 1977: 76)[7]. Hodson (1982)[8] 
likewise argues that there is a distinction between our conceptual systems, 
which are liable to change being human products, and the actual world, to 
which our conceptual systems have some relation:
 
	The physical world is real and scientific theories are real, 
	but they are not identical (there is an ontological distinction 
	between them)...Similarly, 'electron' and 'magnetic field' are 
	real concepts, having an existence independent of individuals 
	and having relationships with other concepts whether or not 
	anyone appreciates that relationship. But in these cases we 
	do not know whether they actually exist or not. 
			Hodson (1982: 27)
 
	Grover Maxwell (1962: vii) in a paper on The Ontological Status of 
Theoretical Entities  advocates a position of extreme realism: 

	The thesis of this paper, bluntly put, is that electrons, 
	photons, and even electromagnetic fields are just as real, 
	and exist in the same full-blooded sense, as chairs, tables, 
	or sense impressions. [9] 

Derek Hodson (1982: 24) argues that:
 
	Even if we do reduce theoretical entities to mere prediction 
	devices the fact still remains that something causes things to 
	behave as they do. There is 'something out there', something 
	that exists and, in my view, science is an attempt to find out 
	what that 'something' is. Scientists are not just concerned with 
	successful predictions, they are concerned with what is. 
	...Theories work as well as they do, and predict successfully, 
	because the entities they involve actually exist.
 
	Ian Hacking (1984)[10] argues that since entities such as electrons 
are used as tools, as instruments of inquiry, then they are entitled to be 
regarded as real. Resnik (1994: 401) summarises Hacking's argument for entity 
realism:
 
	(1)  We are entitled to believe that a theoretical entity is real 
	     if and only if we can use that entity to do things to the world. 
	(2)  We can use some theoretical entities, e.g. electrons, to do 
	     things to the world, e.g. change the charges of nobium balls. 
	(3)  Hence, we are entitled to believe that some theoretical entities, 
	     e.g. electrons, are real.  [11]
 
	In an attempt to resolve the Gordian knot the philosopher Rom Harre  
(1961: 85)[12] has argued that stones and electrons belong to different 
ontological classes, and that both stones and electrons exist, but in 
different senses of TexistU. Harr  (1986)[13] stratifies the ontological 
status of realism into a set of three realms:
 
	Realm 1 is the realm of the directly accessibe material world of 
		objects and properties that can be sensed unaided. 
	Realm 2 is the realm of those things which can be accessed through 
		instrumentation. These are initially proposed through 
		logical reasoning. 
	Realm 3 is the realm of those things which are beyond sensory 
		experience and instrumentation but are accessed through 
		logical reasoning alone. 
			Monk (1994: 5) [14] 

Electrons would arguably belong to Realm 3 as its status is entirely that 
of a logically deduced reality.
 
V.  Quantum mechanics and quantum reality
_________________________________________
 
	Classical physics replaced the question why with the question how. 
Answers to the latter question came in the form of descriptions of motion 
through space and time. The language of quantum mechanics replaces the 
question how with the question what.. What is the outcome of carrying out an 
experiment? Quantum mechanics does not provide a picture of how the outcome of 
an experiment comes about. It is, rather, a mathematical formalism that 
enables calculations to be carried out on what the outcome(s) of an experiment 
may be. Peterson (1985: 305) quotes a remark by Niels Bohr :
 
	There is no quantum world. There is only an abstract quantum 
	physical description. It is wrong to think that the task of 
	physics is to find out how nature is. Physics concerns only 
	what we can say about nature. [15]
 
	Do electrons exist? Are electrons some kind of 'thing', and how far do 
they resemble a lump of metal or other 'common-sense' objects? A scientific 
theory is usually viewed as consisting of a formal structure, in which 
theorems are derived from a limited number of axioms. Some of these theorems 
are interpreted by 'correspondence rules' as statements about things which can 
be observed. Such a structure can coordinate a range of empirical laws. The 
terms in the axioms, however, are not generally directly interpreted by being 
linked to observational reports or the result of measuring operations. 
'Electrons' are, on this desciption, theoretical terms which do not correspond 
to directly observed entities. Phenomena such as tracks in a bubble chamber 
consist of strings of bubbles, and not the 'particles' which are supposed to 
produce them. The question then arises as to do the theoretical terms refer to 
any kinds of 'entity' at all?
 
VI.  Conclusion
_______________
 
	A positivist would interpret the question 'Do electrons exist?' by 
replacing it with the question 'Does the theory of electrons make correct 
predictions?' An instrumentalist or pragmatic viewpoint would interpret talk 
about electrons as simply a convenient fiction for co-ordinating the results 
of observations. A realist interpretation would be that electrons really exist 
independently of theories. Since both instrumentalist and realist 
interpretations agree that the theory is successful a positivist would argue 
that is all that can be said. The answer and interpretation that is given to 
the original question of 'Do electrons really exist?' is therefore a 
reflection of the individual's philosophy of science and ultimately their 
stance on the nature of reality.
 
References
__________

[1]   Wallace, W.W. (1979): From a realist point of view: Essays on the
	philosophy of science (University Press of America: 
	Washington D.C., USA).
[2]   Stoppard, T. (1988): Hapgood (Samuel French: London).
[3]   Hanson, N.R. (1972): Patterns of Discovery  (Cambridge: Cambridge
	University Press).
[4]   Kuhn, T. (1970): The structure of scientific revolutions (2nd edn.)
	(University of Chicago Press: Chicago).
[5]   Millikan, R. (1950): Autobiography (Prentice-Hall: New York).
[6]  Holton, G. (1978): The Scientific Imagination: Case Studies
	(Cambridge University Press: New York).
[7]   Morgenbesser, S. (Ed.) (1977): Dewey and His Critics (Journal of
	Philosophy publication), pp. 76-165.
[8]   Hodson, D. (1982): 'Science - the pursuit of truth? Part II', School
	Science Review, Vol. 63, pp. 23-30.
[9]   Maxwell, G. (1962): 'The ontological status of theoretical
	entities', in H. Feigl and G. Maxwell (Eds.), Minnesota Studies 
	in the Philosophy of Science Volume III (University of Minnesota 
	Press: Minneapolis), pp. 3-27.
[10] Hacking, I. (1984): 'Experimentation and Scientific Realism', in J.
	Leplin (Ed.), Scientific Realism (University of California Press:
	Berkeley, CA.), pp. 154-172.
[11] Resnik, D. B. (1994): 'Hacking's Experimental Realism', Canadian
	Journal of Philosophy, Vol. 24, No. 3, pp. 395-412.
[12] Harr, R. (1961): Theories and Things  (Sheed and Ward: London).
[13] Harre, R.  (1986): Varieties of Realism (Basil Blackwell: Oxford).
[14] Monk, M. (1994): 'What do epistemology and ontology have to offer in
	considering progression in physics education?", paper presented 
	at the International Conference on Thinking Science for Teaching: 
	The Case of Physics (22-27 September 1994, Universi di Roma 
	"La Sapienza").
[15] Peterson, A. (1985): 'The Philosophy of Niels Bohr', in Niels Bohr: 
	A Centenary Volume,  A. French and P. Kennedy (Eds.) 
	(Harvard UniversityPress: Cambridge, MA).