Hilary Putnam, the Philosopher of Science Who Didn't Mind Refuting Himself

He was well-grounded in physics and mathematics but strongly resisted the dominance of scientism, and was known for his ability to turn on his own arguments when he thought the facts merited reinterpretation.

Professor Hilary Whitehall Putnam, recognised as one of the foremost analytic philosophers of the 20th century, died on March 13, 2016, at the age of 89. He retired as Cogan University Professor at Harvard University in 2000 after having served there since 1965.

Putnam was well-known for his breadth of thinking, so much so that he is compared with the versatility of Aristotle. Many of his arguments in the central domains of philosophy are provocatively construed and vividly presented. Such contributions have changed the character of philosophical thinking over the past few decades with radically altered positions and new conceptual moves. What characterises him most is his immunity to dogmatism precisely because of his penchant for self-questioning and a willingness to change his mind on the perennial problems of philosophy.

Putnam probed extensively into issues in metaphysics, epistemology, philosophy of mathematics, philosophy of physics, philosophy of language, philosophy of mind, ethics and value theory. His intellectual career begins with working, along with three other mathematicians, toward a solution of the tenth problem of David Hilbert. And together with Martin Davies, he developed the Davies-Putnam algorithm for the Boolean satisfiability problem.

In the philosophy of science, Putnam subscribed to scientific realism, the belief that theoretical claims of science are to be taken as describing reality – that science aims to produce true descriptions of things in the universe. This realist position is buttressed by his ‘no-miracle argument’, the claim that (in his words) “realism is the only philosophy that does not make the success of science a miracle”. What explains the extraordinarily successful scientific theories in empirical prediction and intricate causal control of nature would be a miracle if not for their approximation to the truth about reality.

Although Putnam was very well-grounded in physics and mathematics, he strongly resisted the dominance of ‘scientism’ – the view that all genuine knowledge is ultimately reducible to that of the natural sciences. This resistance was his criticism of logical positivism, according to which the sole basis of knowledge is that which can be scientifically verified. Indeed, Putnam had taught a course at Harvard titled ‘Non-scientific Knowledge’ that discussed the wisdom that comes from ethics, aesthetics and religion.

The fact-value entanglement

Scientism involves the orthodox belief that science’s cognitive validity depends on its absolute reliance on objective facts, and hence science is value-free. Against this orthodoxy, Putnam insists on fact-value entanglement in the discourse of science. While choosing between different theories and paradigms, the scientist’s choice is not just based on bare facts, but also on values like explanatory simplicity and theoretical elegance.  

The fact-value entanglement is true, for Putnam, of discourses like ethics and politics. Ethical and political judgments cannot trade only in evaluative assertions, in as much as value judgments themselves embody factual claims. If, for example, an ethico-political comment is made to the effect that some particular candidate is corrupt, the comment is not just a judgment of value-criticism but is equally founded on facts about the activities and attitudes of the candidate.

Much as Putnam had shot into prominence for his rejection of the fact-value dichotomy so endemic in philosophy since David Hume down to contemporary analytic philosophy, he was famous for several original ideas on central issues like mind and body, meaning and truth, and knowledge and scepticism. In the philosophy of mind, he was famous for the functionalist view that a mental state is to be defined in terms of the relation of an internal state to sensory input and behavioural output of a system. In other words, being a mind is to be understood as having internal states that are what they are because of their functional role in the input-output relational complex.

Putnam was eminently recognised for his theory of meaning – according to which meaning in language cannot be explained in terms of internal mental states like ideas and mental images. “Meaning just ain’t in the head” is how he had put the point. Rather, what we mean by a word is crucially determined by its causal relation to the external world. This theory is famously known as semantic externalism; it is the same theory that had become an argument for the possibility of knowledge against scepticism. If externalism is true about meanings in language, it is also true about the meanings of perceptual language, which purports to be knowledge-claims about the external world.

The brain in a vat

The two most widely cited philosophical thought-experiments owed to Putnam in the context of meaning and knowledge are the ‘Twin Earth’ case and the ‘Brain in a Vat’ (BIAV) case. The latter thought experiment is exploited in articulating epistemological externalism, which is meant to undercut epistemological scepticism. The BIAV argument builds on the science-fictional supposition that your brain has been removed from your body and placed in a vat of nourishing fluids that keep the disembodied organ alive. The brain is then connected to a supercomputer whose program produces electrical impulses that stimulate the brain so as to generate illusions of a perfectly normal scenario, say, the sight of a tree in front of you.

If you are a BIAV, then your tree-experience is qualitatively indistinguishable from that of normal tree-perceiver. But clearly your computer-induced experience as of a tree is not an experience of a tree because, in the BIAV situation, there are no trees. And if the BIAV situation is conceivable and you have no way of knowing that right now you are not a BIAV, then your claim to know that there is a tree in front of you is just an illusion of a tree. This is the argument of epistemological scepticism.

Putnam’s refutation of scepticism consists in his demonstrating that the BIAV argument is necessarily false because it is self-refuting. If I am a brain in a vat, then my utterance of ‘brain’ or ‘vat’ does not refer to a brain or a vat because this utterance is causally connected to neither brains nor vats. This argument follows from Putnam’s semantic externalism – that the meaning of a word is determined by its relation to the external world. Now, if it is true that I am a brain in a vat, then the sentence ‘I am a brain in a vat’ is false because ‘brain’ and ‘vat’ here do not refer to brains and vats (but visualisations of them). Putnam therefore draws the conclusion that the BIAV argument is inconsequential to a defence of epistemological scepticism.

More in the manner of Bertrand Russell and William James, Putnam preferred to project the image of philosophy as reasserting its traditional role of guiding, edifying and inspiring human life. Four of his last works – Realism with a Human Face (1990), Words and Life (1994), Jewish Philosophy as a Guide to Life: Rosenzweig, Buber, Levinas and Wittgenstein (2008) and Philosophy in the Age of Science: Physics, Mathematics and Skepticism (2012) – are a testimony to that reassertion.

It is interesting and rather unusual to note that Putnam lived at a commune in Cambridge, Massachusetts. He was an active supporter of the American Civil Rights Movement of the 1960s and 1970s, and had organised movements that opposed American military intervention in Vietnam. At Harvard, he had affiliated himself, in the capacity of an official Faculty Advisor, with Students for a Democratic Society and joined the Progressive Labour Party, an offshoot of the Communist Party.

It is also noteworthy, as far as Putnam’s academic association with India is concerned, that he had delivered the last Skype talk of his life, titled ‘Thought and Language’, in 2015 at an international conference on the philosophy of Hilary Putnam held at the Indian Institute of Technology, Mumbai.

Putnam’s academic career is marked by constant self-criticism and intellectual restlessness as he kept on revising his major views and even rejecting earlier views in favour of a new outlook. When he was ridiculed by some critics for changing his mind, Putnam responded in confident self-defence: “A philosopher’s job is not to produce a View X and then, if possible, to become known as Mr. View X or Ms. View X.”

Two striking encomiums generated by Putnam’s demise deserve to be quoted. Martha Nussbaum of the University of Chicago wrote in the Huffington Post that Putnam was “one of the greatest philosophers this nation has ever produced.” She compared him to Aristotle in the range of his “creative and foundational contributions”. Noam Chomsky of MIT, who was Putnam’s high-school-mate in Philadelphia, complimented him by saying that he was “one of the finest minds I’ve ever encountered.”

Indeed, the world’s philosophical community in particular and intellectuals in general will miss one of the most versatile and fertile minds the last century had produced in the West.

Bijoy Boruah is professor of philosophy in the Department of Humanities and Social Sciences, Indian Institute of Technology, Delhi.