Australian materialism didn’t begin with David Armstrong. That honour goes to the first Australian philosopher of note, Samuel Alexander. But in Armstrong, materialism (or physicalism as he calls his more mature view) has found its most articulate and persuasive advocate. As David Stove notes in his remarks commemorating Armstrong’s retirement, there is in fact hardly any comparison. Armstrong’s influence has been enormous. The department where he taught for decades was known around the world simply as Armstrong’s department. Fifty years after his appointment to Sydney’s fabled Challis Chair of Philosophy, he remains Australia’s most important philosopher. Without qualification, he has been one of the twentieth century’s most influential thinkers.
Armstrong was born in Melbourne in 1926. After serving in the Royal Australian Navy from 1944 to 1946, he took his undergraduate degree in philosophy at Sydney University. He graduated with the University medal in 1950. Like many Sydney students of his generation, Armstrong was influenced immensely by the iconoclastic philosopher John Anderson, holder of the Challis Chair from 1927 to 1958. As Armstrong wrote in Quadrant in 1983, “Anderson had an answer to every conceivable question. It was ‘No.’” (The quip is said to have originated with the poet James McAuley.)
As Armstrong tells it, Anderson’s personality exhibited itself, not just in its intellectual reach, but also in its audacity: “Every icon was to be smashed: God, immortality, free will, moralism, the common good of society. … Every canon of contemporary educational thought was flouted. Yet it was all very inspiring. One stood on the shoulders, or, indeed, the necks, of the mighty philosophers of the past.”
After graduation, Armstrong read for a B.Phil. degree at Oxford under the supervision of H.H. (“Perception”) Price. Arriving at Exeter College where his grandfather had served as Rector from 1928 to 1943, he found himself unwilling to abandon the realism and empiricism he had picked up from Anderson. Even so, he gained some appreciation for the precision of Oxford analysis, while never accepting that analysis alone could be the whole of philosophy.
Following his graduation he taught for a year at Birkbeck College within the University of London. While there he attended Michael Oakeshott’s lectures, taking from them a new appreciation of the evolution and flexibility of traditions, an insight that eventually found its way into his paper “The Nature of Tradition.”
Anxious to return to Australia, he took a job lecturing at Melbourne University in 1956. He stayed in Melbourne for eight years, completing his Ph.D. there in 1960 under the supervision of Camo Jackson. In 1964 he was appointed the Challis Professor of Philosophy at Sydney, a position he held for 28 years.
Since then, Armstrong has held visiting appointments at numerous universities, including Stanford, Yale, Notre Dame, the University of Wisconsin, the University of Texas, the University of California at Irvine, and the University of Graz in Austria; but since returning from London, Australia has always been his home. He is a Foundation Fellow of the Australian Academy of the Humanities and following his retirement in 1991 he became a corresponding Fellow of the British Academy. In 1993 he was appointed an Officer of the Order of Australia.
At the heart of Armstrong’s intellectual work is his uncompromising defence of physicalism, the view that the world is nothing but a single spatio-temporal system, a single causal nexus bounded by space and time and fully describable in terms of (a completed) physics. This view commits Armstrong to three inter-related theses. First, he is committed to naturalism, the view that the world contains no supernatural or extra-natural parts such as gods or angels. Second, he is committed to materialism, the view that the world contains no (natural but) non-material entities such as vital forces or Cartesian minds. Third, he is committed to physicalism, the thesis that all (material) phenomena, whether mechanical, chemical, biological or social, are ultimately reducible to the physical. Armstrong’s metaphysics (or theory of being) and his epistemology (or theory of knowledge) are thus both wholly physical in outlook. Minds, spirits, numbers, propositions, possibilia, fictional entities, ideal standards of value – all are either to be reduced to the physical or abandoned.
Philosophy thus finds itself on a continuum with science. While science does the heavy lifting of observation, working tirelessly to discover the “geography and history of the universe” (taking geography in this context to include all space and history to include all time, including the future), philosophy works to clarify the concepts and other basic building blocks that science uses. As Einstein famously remarks, just as philosophy, when isolated from science, becomes empty, “science without epistemology is – insofar as it is thinkable at all – primitive and muddled.”
Armstrong’s definitions of naturalism, materialism and physicalism are especially useful in that they keep clear the distinction between the world as it is and the world as it is perceived. W.V. Quine’s competing definition, which identifies naturalism with the thesis that all knowledge is scientific knowledge, makes this distinction harder to maintain. Even so, for both Armstrong and Quine, philosophy remains a close working partner of the natural sciences.
Armstrong’s physicalism requires defence partly for external and partly for internal reasons. Externally, it needs to be shown that physicalism gives a better account of the world than do its non-physical competitors (for example, creationism). Given the enormous predictive and explanatory success of science, this debate is now virtually closed. Internally, however, naturalism requires additional defence, since many scientific theories appear to commit us to more than just tables and chairs, genes and DNA molecules, black holes and elementary particles. Even some of history’s best scientific theories have sometimes appeared to commit us, in varying degrees, to a variety of non-physical (and perhaps non-natural) entities, including non-physical minds, abstract mathematical entities, biological forces, and non-actual fictional and modal entities. Defending physicalism requires that such entities be shown to be either reducible to more basic physical objects or capable of elimination.
It was in this context that Armstrong began his work on perception and the mind, as well as on wider issues in metaphysics. Like Bertrand Russell and Ludwig Wittgenstein, he eventually was to conclude that the world is a totality of facts (things standing in relation to one another), not just of things. He also was able to give (at least nascent) physicalist accounts of not just minds, but also knowledge, laws of nature, mathematics and possibilia.
For many, Armstrong is best known for his defence of a forerunner of functionalism, the most widely accepted theory of mind today. If a slogan is needed for Armstrong’s earlier view, it is that mind equals brain. Put in slightly different terms, Armstrong’s basic thesis was that mental states can be identified with brain states or, more properly, with states of the brain and central nervous system. Just as one need not postulate non-physical souls or vital forces to understand life as a purely physico-chemical phenomenon, one need not postulate non-physical minds to understand the mental. Initially this theory was known as the causal theory because, unlike Gilbert Ryle’s behaviouristic reduction of consciousness (the theory it was designed to replace), it allowed for a common-sense two-way causal interaction between mind and body. Later the theory came to be known as central state materialism or simply as the identity theory.
In response to the puzzle of why, if mental states are identical to physical states, we don’t experience them as such, Armstrong introduced the analogy of the headless-woman magic trick. In the illusion, a woman is placed on stage against a black background, suitably lit. Unknown to the audience, a black cloth is placed over her head and it then appears that she has no head. As Armstrong points out, this illegitimate shift from “I cannot perceive that the woman has a head” to “I perceive that the woman has no head” is very similar to Descartes’ mistaken shift from “We are not introspectively aware that mental processes are brain processes” to “We are introspectively aware that mental processes are not brain processes.”
As Armstrong remarked some years later, had he given the matter just a little more thought, he would also have adopted the functionalist’s addendum that an important distinction needs to be made between type-type and token-token identities of the mental and the physical. As he explains, “A few moments’ thought about the matter would have shown me that there were problems in identifying, say, the type pain with a certain physiological type. Even if every pain is a purely physiological state, it is not at all obvious that that which plays the causal role of pain in different minds, different species, etc., must always be the same sort of physiological event.”
Related to Armstrong’s theory of mind is his theory of perception. Troubled by the argument from error, most philosophers prior to Armstrong accepted one form of representation theory or another. Since perceptions can sometimes fail to be veridical (the water on the glimmering highway turns out to be a mirage, the star we see in the sky in fact disappeared millions of years ago), many philosophers have accepted the view that we are acquainted in our minds, not with the object itself, but with a mere copy or representation of the object. Armstrong, in contrast, argues in favour of direct realism, the claim that, when successful, perceptions allow us to be directly acquainted with the objects being perceived. Once again, the theory relates closely to genuine physical, causal connections between ordinary objects and the brain.
Armstrong’s theory of belief then follows quite easily. Rather than adopting a linguistic theory, Armstrong adopts instead a physicalist account in which belief (and other mental concepts) are to be identified with a particular type of causally efficacious brain state. Following a tradition initiated by David Hume and later developed by Frank Ramsey, beliefs are the “maps by which we steer.” They are the brain states that commit us (or which under different circumstances would commit us) to action. The theory is once again part of Armstrong’s rebellion against behaviourism. Beliefs are not to be thought of as being identical to behaviour. Instead they are the causes of behaviour.
For Armstrong, knowledge is then, as in all traditional theories, a specific kind of true belief. What distinguishes it from other kinds of true belief is its simple reliability. Unlike traditional theories from the time of Plato to the present, knowledge need not be justified. For an agent, A, to know belief, B, B must be true; but A need not know what justifies him in believing that B is true. All that is necessary is that the belief reliably track the phenomenon in question. A broken clock will be right twice a day, but this alone (assuming the clock were able to believe the time it represented) won’t give it knowledge. In contrast, a thermometer that reliably tracks its ambient temperature would have knowledge (assuming once again that it also had the requisite ability to believe).
Having dealt with the mental, by the late 1970s Armstrong began to turn his attention to a more detailed analysis of the physical. Specifically, he began to ask what makes physical objects similar or dissimilar. The obvious answer is that similar objects are so in virtue of their shared properties and relations; dissimilar objects are so in virtue of their different properties and relations. The issue again goes back to Plato, but unlike Plato (who accepted the existence of a wide range of properties, whether instantiated in the physical world or not), Armstrong worked to develop a view in which only physical properties and relations need be posited. If science requires an electron to have a negative charge, then it’s a good bet the property of having a negative charge exists. If science requires multiple electrons to share the exact same negative charge, then it’s a good bet the property is a universal, the kind of property that is capable of being in two distinct places at once. Armstrong then applied his theory of physical universals to a series of traditionally challenging puzzles.
On its face, the idea of truth seems relatively straightforward. The sentence “The cat is on the mat” is true just in case there is, in the world, a cat, a mat and a suitable relation existing between the two. The sentence “These two glucose molecules have bonded together” is true just in case there is, in the world, an appropriate pair of glucose molecules together with the shared relation of being bonded together. It is this kind of simple observation that motivates what has traditionally been called the correspondence theory of truth, the theory that a sentence is true if and only if it corresponds to some fact in the world. However, as Armstrong and others (notably C.B. Martin, Kevin Mulligan, Peter Simons and Barry Smith) have pointed out, mere correspondence is not an especially informative notion. A more accurate way of explaining why “The cat is on the mat” is true is that it is made true by the cat, the mat, and the relation that holds between them. But if this is so, it appears that for any truth there will have to be a truthmaker, some fact in the world that makes the truth true. For Armstrong, these facts are physical and not linguistic. It will be one and the same physical fact that makes both the sentence “Hawaii is north of Tahiti” and the sentence “Tahiti is south of Hawaii” true.
Several puzzles now arise. If every truth requires a truthmaker, what is the truthmaker for the (presumably) true sentence, “If Socrates hadn’t been found guilty, he wouldn’t have been executed.” Assuming this sentence is true, what makes it true? Surely there is no possible but non-actual world in which Socrates is not found guilty and so not executed?
Similarly, what makes it true that a window is disposed to break if hit by a stone? Is there a group of nonexistent worlds in which the window breaks as a result of its being hit by a stone? Do the actually existing stone and glass have dispositional powers in addition to their categorical properties?
Armstrong’s answer to this type of question is that nothing needs to be postulated over and above an object’s physical properties. Dispositions are identified, not with some mysterious powers, but with ordinary physical properties and relations. Glass is disposed to break when hit by a stone because of its actual molecular structure.
In a similar way, mere (non-actual) possibilities are identified with in-principle re-combinations of actually existing elements of the (physical) world. Unicorns are possible (even if non-actual) because the basic building blocks of the world (individuals, properties and relations) could have been rearranged in such as way that unicorns evolved. A five-sided square is not possible because no such re-arrangement would ever result in such a configuration.
It is in this same context that Armstrong uses his theory of universals to develop a non-regularity theory of laws of nature. Here Armstrong’s goal is to develop (contra Hume) a necessitarian, but still fully naturalistic, account of why laws of nature are more than mere statements of regularity. In Armstrong’s account, laws of nature are relations of necessity or probability between universals. For example, consider Newton’s law that every object in a state of rest or uniform motion will remain in that state of rest or uniform motion unless it is acted upon by an external force. Not wanting to accept Hume’s suggestion that such regularities are mere coincidences, Armstrong holds that physical objects are necessarily disposed to act in this way, provided of course that we understand dispositions once again as resulting from an object’s actual physical properties.
The result of all this intellectual work has been that Armstrong, along with so many others of his generation including his good friend David Lewis, have changed the way philosophers do philosophy and see the world. As Armstrong has said on more than one occasion, he has found it a genuine pleasure to spend his life, as D.C. Williams once put it, “grubbing around in the roots of being.”
David Stove’s tribute to Armstrong upon his retirement in 1991 was both generous and moving. It was also true. Armstrong’s influence on philosophy has been enormous, and rightly so. In a country that has been home to so many good philosophers, including Frank Jackson, J.L. Mackie, David Stove, John Passmore, Graham Priest, Peter Singer, Michael Devitt, Philip Pettit, Kim Sterelny, David Chalmers, Huw Price, Peter Godfrey-Smith, Paul Griffiths, Michael Smith, Alan Hájek, Bob Meyer, Richard Routley, Greg Restall, Mark Colyvan and many others, Armstrong (along with two other giants, John Anderson and J.J.C. Smart) has been a dominating figure.
Over the years, Armstrong has also been a great defender of both scientific and humanistic learning. His leadership during the political disturbances within the philosophy department (and later the philosophy departments) at Sydney University has been so ably recounted by James Franklin in his history of Australian philosophy, Corrupting the Youth, that it is hard to justify spending more time going over old ground.
It is also true that Armstrong has been a major figure in advancing what Keith Windschuttle has called the Sydney line, that brilliant combination of realism and empiricism, wedded with an unyielding resistance to moral, cultural and cognitive relativism.
If there is an error in Stove’s tribute, it is in saying that Armstrong’s influence on the general culture of Australia has only been slight. It was an honest mistake. Despite Armstrong’s many years of teaching, his regular contributions to Quadrant and his unyielding defence of scientific and humanistic learning, there is a sense in which Armstrong has always remained cloistered within the walls of philosophy. In Stove’s word, Armstrong was from start to finish a pure philosopher.
Even so, with an additional quarter century of hindsight, there is also a clear sense in which the influence of Armstrong’s ideas on Australian culture has been unrivalled. In a nutshell, Armstrong’s influence on Australian culture has been enormous simply because his influence on world culture has been enormous.
At least within the western world, Armstrong’s version of physicalism, if not quite the received wisdom of the age, has been so remarkably influential that it is hard to imagine it having greater impact. It may be that the proximate cause of people now believing that minds are physical comes from the success of various brain scans and other forms of medical technology, but the distal cause comes from the influence of philosophers and scientists working in the 1950s and 60s who made the mere suggestion of such technology not only possible but plausible. Among such writers, few if any have been as successful as Armstrong in developing such a comprehensive physicalist account of the world.
 David Stove, “David Armstrong, Challis Professor of Philosophy in the University of Sydney, 1964-91,” Quadrant, this issue.
 D.M. Armstrong, “An Intellectual Autobiography,” Quadrant, January/February 1983, 91.
 D.M. Armstrong, “An Intellectual Autobiography,” Quadrant, January/February 1983, 91-92.
 D.M. Armstrong, “The Nature of Tradition,” in Liberty and Politics, O. Harries (ed.), Sydney: Worker’s Educational Association of N.S.W. and Pergamon Press (Australia), 1976, 7-19. Reprinted in D.M Armstrong, The Nature of Mind and Other Essays, St Lucia: University of Queensland Press, 1980, 89-103.
 D.M. Armstrong, What is a Law of Nature? Cambridge: Cambridge University Press, 1983, 3.
 Albert Einstein, “Remarks concerning the Essays Brought together in this Co-operative Volume,” in Paul Arthur Schilpp (ed.), Albert Einstein: Philosopher-Scientist, New York: Harper & Brothers Publishers, 1949, 683–684.
 D.M. Armstrong, “An Intellectual Autobiography: Part II,” Quadrant, March 1983, 71.
 D.M. Armstrong, “An Intellectual Autobiography: Part II,” Quadrant, March 1983, 71.
 D.M. Armstrong, Belief, Truth and Knowledge, Cambridge: At the University Press, 1973, 4.
 D.C. William, quoted in D.M. Armstrong, Universals: An Opinionated Introduction, Boulder, San Francisco, London: Westview Press, 1989, 139.
 James Franklin, Corrupting the Youth, Sydney: Macleay Press, 2003, esp. Ch. 11. Cf. W.F. Connell, G.E. Sherrington, B.H. Fletcher, C.Turney and U. Bygott, Australia’s First, Volume 2: 1940-1990, Sydney: The University of Sydney and Hale & Iremonger, 1995, 164-170.