Etemad Newspaper Interview with Hossein Dabbagh on 'Thought Experiments'

Thought experiments are among those tools of philosophizing through which philosophers in various branches, including ethics, religion, mind, metaphysics, etc., can advance their arguments. In truth, thought experiments are not themselves arguments, but rather they can constitute the premises of an argument. I agree with Daniel Dennett, the American philosopher of mind, that thought experiments cause our philosophical intuitions to leap and to accept the content of the thought experiment in question. In Dennett's words, thought experiments are a kind of "intuition pumps."

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1. Let me begin the discussion with this point that, fundamentally, one of our ways of knowing the world is through thought experiments. In your view, how do thought experiments help us know the external world? In other words, how is the abstract-minded philosopher or the meticulous, observation-oriented scientist convinced, through designing an experiment and then confirming or refuting it, to make a judgment about nature or reality?

Thought experiments are among those tools of philosophizing through which philosophers in various branches, including ethics, religion, mind, metaphysics, etc., can advance their arguments. In truth, thought experiments are not themselves arguments, but rather they can constitute the premises of an argument. I agree with Daniel Dennett, the American philosopher of mind, that thought experiments cause our philosophical intuitions to leap and to accept the content of the thought experiment in question. In Dennett's words, thought experiments are a kind of "intuition pumps." It is as if thought experiments try to recount complex and intricate philosophical matters to us in simpler language through "storytelling," in such a way that their affirmation suddenly rushes upon us. What is meant by intuition in these expressions is the "seeming" of a matter, or, in the terms of our scholars of legal theory, a kind of "approbation" (istihsan). For example, Edmund Gettier, the American epistemologist, in a famous and epoch-making article, tries to convince us by telling a story that knowledge is not justified true belief.

Karl Popper, philosopher of science, believed that thought experiments provide us with epistemic access to the world around us in three ways. In his book The Logic of Scientific Discovery, he introduces three types of thought experiments: heuristic, critical, and apologetic. Heuristic thought experiments seek to construct and illustrate a theory, whereas critical thought experiments, functioning as a reductio ad absurdum, attempt to undermine an established theory. Finally, apologetic thought experiments support established theories. James Brown, a Canadian philosopher of science, later reduced Popper's classification into two categories: "constructive" and "destructive," adding numerous other subdivisions under each of these headings. For example, under destructive thought experiments, at least three further types can be distinguished from one another. The first type concerns those thought experiments that aim to refute a theory by demonstrating a contradiction. The best example of this is Galileo's thought experiment, which rejected Aristotle's theory of heavy and light bodies. Frank Jackson's "Mary's Room" thought experiment, by the Australian philosopher of mind, is another example that shows physicalism is untenable. The second type of such thought experiments relates to situations where a thought experiment attempts to show that the theory in question conflicts with the rest of our beliefs. For instance, Schrödinger's cat thought experiment demonstrates that Bohr's quantum theory is, at the very least, in conflict with our basic beliefs, such as the idea that a cat cannot be both alive and dead at the same time. The third type concerns thought experiments that intend to refute the main hypothesis of the thought experiment itself. For example, in the "Violinist" thought experiment by Judith Jarvis Thomson, an American moral philosopher, she shows that although the "right to life" applies to everyone, even a fetus, abortion is morally permissible. Constructive thought experiments, as their name suggests, seek to help establish something by providing examples and illustrations. Consider, for instance, the "Chinese Room" thought experiment by John Searle, an American philosopher of mind and language. He attempts, in defense of artificial intelligence, to show that computers, like humans, can possess consciousness and minds. Furthermore, Newton's thought experiments about the motion of the moon and Maxwell's demon concerning the second law of thermodynamics (entropy) are also prominent examples of constructive thought experiments.

It is clear that all these experiments—despite the various disputes about them—share one thing in common, and that is that they attempt to demonstrate something about what is going on in the external world. But it should not be forgotten that some thought experiments speak about the external world itself at a higher level. For example, the Twin Earth thought experiment by Hilary Putnam, an American philosopher of mind and language, tries to defend a kind of direct or naive realism against sophisticated realism.

2. Can one speak of good and bad thought experiments? Is there a criterion for such a judgment? If the answer is yes, what is the nature of this criterion itself? Philosophical or scientific?

In my view, it is entirely conceivable to speak of appropriate/effective and inappropriate thought experiments, just as we characterize various arguments as good or bad. For example, Galileo's thought experiment is truly a very successful one. But if you ask what criterion exists for judgment here, it must be said that it is precisely the same criterion that exists for various arguments. Some thought experiments have the capacity to be tested by experience. For instance, Galileo's thought experiment has this capacity, and through empirical testing, one can pronounce it effective. But not all thought experiments are like this; that is, the hand of experience does not caress them. For example, Thomson's violinist thought experiment is not like this. The philosopher or the individual who is the audience for such an experiment strengthens their "imagination" to conceive of such an experiment in their mind. These kinds of thought experiments, which lack an empirical test (or at least have not been tested by experience so far), are exactly like parts of an argument. As long as no objection has been raised against your thought experiment as a premise of an argument, you are entirely rationally justified in evaluating your thought experiment as effective and good. This does not mean that you cannot do so even if your thought experiment is opposed. For example, I believe Thomson's thought experiment, despite all the opposition it has faced, has turned out to be successful.

Another point that must be considered is that, whether we like it or not, destructive thought experiments used as reductio ad absurdum usually turn out better than constructive ones. For example, suppose you believe in classical or act-consequentialist theory in ethics. I can clearly design a thought experiment for you in which, according to your theory, a doctor is morally permitted to take the lives of five people to save one, and this is contrary to our basic moral beliefs. This thought experiment simply undermines the strength of your theory and, in this respect, is a good experiment. But it must be admitted that sometimes judging the goodness or badness of thought experiments becomes somewhat difficult. For example, Frank Jackson designs a good thought experiment to refute physicalism. In response, Daniel Dennett designs another good thought experiment to refute his thought experiment. Both arguments seem to be good arguments, although I have more sympathy for Jackson.

Finally, the acceptance of thought experiments by the philosophical community should not be forgotten. Some thought experiments, due to their strength, find a place in the hearts of philosophers and empirical scientists and are considered self-evident, to the extent that philosophers no longer see a need to argue for them. For example, John Rawls's "original position" thought experiment is one of the good experiments that enjoys high acceptance among philosophers. Although Rawls's successors and students (like Scanlon and Parfit) try to develop his thought experiment, no one doubts the thought experiment in its entirety.

3. Is there a difference between thought experiments in the world of philosophy and scientific thought experiments? What are the differences?

If by "scientific" here you mean empirical science, then of course it must be said that there are differences between thought experiments in philosophy and the empirical sciences. The most important difference is that thought experiments in the empirical sciences—as their name suggests—are mostly concerned with the sensible world and empirical theories, whereas thought experiments in philosophy (for example, in ethics, philosophy of religion, and metaphysics) are sometimes so abstract that they have no place in the sensible world. For instance, the thought experiments of Galileo's falling bodies, Newton's bucket, Einstein's elevator, and so on, are concerned with the material world and the theories of empirical science, even though some of them cannot be empirically tested. In contrast, the thought experiments of Rawls or Putnam that I mentioned are so abstract that no empirical test will ever touch them. There are exceptions, of course. Sometimes one can find thought experiments in philosophy that are empirically testable, or thought experiments in the empirical sciences that are not. For example, Peter Singer's "Drowning Child in the Pond" thought experiment, which shows we are morally obligated to help others even in distant countries, is entirely empirically testable. On the other hand, Einstein's thought experiment about someone running at the speed of light cannot be tested empirically—at least not yet.

But the similarities should not be overlooked. Despite some differences between thought experiments in philosophy and the empirical sciences, both are products of the imaginative faculty of a philosopher or someone seeking to reason. By strengthening their imagination, the designer of a thought experiment tries, through telling metaphorical or even real stories, to turn the audience's mind in a direction it has not gone before.

4. Is there any intellectual or scientific activity that has not made use of thought experiments? It seems chemistry or anthropology have not had a suitable relationship with this tool. What is the reason?

I believe that wherever reasoning enters, thought experiments can also make their appearance. For this reason, it is natural to suppose that, in principle, any intellectual activity, whether in the humanities or the sciences, can use thought experiments. But which sciences have used this tool so far is an empirical-historical question. It is quite clear that I do not know the history of all sciences. However, as far as I know about the history of chemistry, it has, in fact, made use of thought experiments. For example, Kekulé, the German chemist, saw in his dream a snake biting its own tail, and this led him to conceive the chemical structure of benzene as a ring (hexagon). But you might object: can a dream even be considered a kind of thought experiment? We construct thought experiments consciously, whereas dreams come to us unconsciously. I understand this objection well. But let us, for the sake of advancing the discussion, broaden our understanding of thought experiments for now. That is, let us imagine that thought experiments, as a "gathering place," also encompass dreams and reveries. In this case, the presence and entry of metaphors into thought experiments becomes serious. In my view, within this expanded conception of the thought experiment, it might be said that since thinking without "imagination" and the use of metaphors is almost impossible, and metaphors have an unbreakable link with thought experiments, thinking without thought experiments is impossible. Although thought experiments are impossible without metaphors, one can name metaphors that are not thought experiments.

Let me also make a few points about anthropology. In my view, the history of thought concerning human nature is in fact replete with various thought experiments. Consider Hobbes's Leviathan or Machiavelli's The Prince. They clearly depict the condition of human beings in this world metaphorically through a thought experiment. Consider also Rousseau's discussion of the social contract. He attempts to explain the human condition in this world by imagining an "unwritten social contract." This reaches its peak with Hegel and Marx. Hegel imagined that all of history is propelled by what he called the "Absolute Spirit," and our relationship to it as human beings is like that of chess pieces to a chess player. When Marx divided different social classes and spoke of "alienation," he was practicing a thought experiment. These examples, and many others in the history of philosophy, all show how thinkers, when discussing the human condition in the present world, were inevitably compelled to delineate numerous thought experiments with the aid of metaphorical thinking.

The penetration and influence of thought experiments in Islamic philosophy is also worthy of consideration. The most obvious thought experiment in Islamic philosophy belongs to Avicenna. In his book The Cure, by designing an experiment called the "Floating Man," he tries to argue that the soul is immaterial and does not perish after the body's disintegration. But if we consider a broad conception of thought experiments, many metaphors in Islamic philosophy can also be considered a type of thought experiment. For example, Suhrawardi's various metaphors are exemplary in this regard. He saw God as the Light of Lights and this world as the manifestations of that light. It is clear that Suhrawardi, with this fine "imagination," delineates a thought experiment to advance his mystical argument.

5. What is the role of thought experiments in bringing the language of empirical science or philosophy closer to the language of the general public? Is this influence constructive, or does it cause people to "think" they understand exactly what scientific theories are saying?

As I mentioned above, most philosophers try to design thought experiments in a story-like fashion. One might say that thought experiments with more fluid narratives enjoy greater popularity. For example, consider Thomson's thought experiment on abortion, and how, with a fluid story, it makes a complex philosophical issue comprehensible to everyone. The storytelling nature of thought experiments makes it possible for those who have not studied philosophy to grasp certain complex arguments. As another example, consider Singer's thought experiment about helping others, which transcended the boundaries of the philosophical community; Singer himself presented it in his public lectures, and it was well received. For this reason, I think employing thought experiments is also a kind of "philosophy in simple language," and in this respect, it is constructive.

However, I have some doubts that thought experiments in science can necessarily aid public understanding. Some of Einstein's thought experiments are truly complex. The truth is that the general public does not need to understand scientific issues. For this reason, thought experiments in the empirical sciences should be left to scientists and philosophers of science. They know better how to interact with one another. What is important in this context is understanding those philosophical issues that grip us in everyday life, namely ethical issues. It is here that the thought experiments of moral philosophy can make ethical complexities understandable to everyone.

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PDF file of the Etemad newspaper interview with Hossein Dabbagh on "Thought Experiments"

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Thought Experiments in Conversation with Dr. Hossein Dabbagh

Thought Experiments, Etemad Newspaper, Issue 3084, 15/10/2014, Page 12 (Thought)

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