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Milesian philosophy of physical explanation


To: Sean R.
From: Geoffrey Klempner
Subject: Milesian philosophy of physical explanation
Date: 23rd November 2011 11:48

Dear Sean,

Thank you for your email of 16 November, with your essay for the first three units of the Ancient Philosophy program, in response to the question, ''The possibility of a physical explanation of the nature of the world and how it came to be was a philosophical discovery.' -- how come?'

This is a very good essay which to a large extent succeeds in answering the question. You make good use of your study of Thales and Anaximander, and you also quote Russell in support of your argument.

I do sense a certain degree of strain in the way you have framed your argument, beginning with Russell's question, whether there is 'any knowledge in the world which is so certain that no reasonable man could doubt it', then admitting in your last paragraph that 'there may never be a knowledge of the world which no reasonable man could doubt', while upholding the value of 'philosophical doubt and inquiry'.

The question, as it stands, has a hint of paradox, and this partly accounts for the difficulty. Seeking a physical explanation of the nature of the world is physics, not philosophy. Physicists, or scientists generally, proceed by means of hypotheses which they not only test for internal consistency, but also compare with actual observation. A physical theory can be wrong, not because it commits any errors in logic, but simply because the question put to nature receives an answer which contradicts the answer that was expected.

Philosophy is the art of reason, and its results, such as they are, do not need to be corroborated by experience. A philosophical claim, if false, is false because of an error of reasoning or logic. (We do not always find the error.)

One of the things philosophers are interested in, however -- and it is one of the aspects of philosophy which most occupied Russell -- is the theory of knowledge or 'epistemology'. One of Russell's books is entitled, 'Human Knowledge, Its Scope and Limits'. You can reason about knowledge or its possibility, and such reasoning is itself not directly tested by experience, because it is presupposed whenever we test a theory against experience. In that book, as well as in his more accessible work 'Problems of Philosophy', Russell seeks to persuade the reader by means of reason. He is not putting forward a scientific theory.

At this point, one needs to insert a caveat, because one of the major themes in contemporary analytic philosophy has been the denial of an absolute divide between the methods of science and the methods of philosophy. The American philosopher W.V.O. Quine in his essay 'Epistemology Naturalized' asserted that 'there is no First Philosophy' (in the sense of Descartes' 'Meditations on First Philosophy'). Epistemology is a scientific inquiry, just like any other.

In other words, there is a debate here about the scope of philosophy: whether it is ultimately different from science, as Descartes thought, or whether it is in some sense continuous with science as Quine argues. In this topic, Russell is closer to Descartes than to Quine, even though his discoveries in the field of symbolic logic have played a major part in the development of Quine's views.

There is no hint of this debate in the work of the earliest philosophers, because the question simply hadn't arose. And yet it was not long before the split between physics and philosophy became apparent. You quote my claim that there are 'two thoughts' involved in the idea that the 'universe conforms to reason'. The first thought is that nature obeys laws, making it possible for us to put questions to nature and receive truthful replies (any false conclusions are the result of our ignorance or ineptitude). That's consistent with what the Milesians believed. The second thought, however, is that there are necessary truths about the world which can be discovered by reason alone. You don't need to consult experience, because there could not be a universe which did not conform to those truths.

An example would be the belief that the principle of causality is necessary and knowable a priori. That is something that the philosopher Kant tried to prove. This claim is not accepted today, at least by the majority of physicists. Einstein expressed his conviction that 'God does not play dice with the universe', but he did not attempt to prove this by means of reasoned argument. For him, it was a principle of scientific 'faith'.

At the time of the Presocratics, the split between physics and philosophy arose with the Eleatic school, Parmenides, Melissus and Zeno. Physics deals with mere appearance. Whereas reality, or what 'Is', is something totally different. That we live in a world of plurality, movement and change is a mere illusion.

Philosophy gave birth to physics. Yet the child of philosophy has now grown up and become independent, to the point where physicists such as Stephen Hawking openly challenge the continuing validity of philosophy as a discipline. See my answer to Alan (who is actually, on of my Pathways students taking Ancient Philosophy!) at

All the best,