The Material and Spiritual Rationales Are Inseparable

There are sound spiritual reasons for the ecological and environmentalist perspective—for minimizing pollution and harm to ourselves, to future generations, to the earth. Are these consistent with the material reality and aspirations of chemistry and chemical industry? One would like to think they are. But what of the realities? I want to take a hard, personal look at this fundamental tension. And also search for what is special about Green or Sustainable Chemistry, facing up to the obstacles confronting the field. And, while reaching for a measure of transformation, a multifaceted Green Index, to come back to a moral perspective on our creative activities. Chemists and chemical engineers are prone to believe that the general public does not recognize the contributions that chemistry has made to our health and our standard of living. And we often cringe at the perception that others blame us (and the great industries that employ us) for fouling our own nest, the infinity of ways we have found of affecting adversely our bodies and the earth by producing on the megaton scale the unnatural. Each of these adverse opinions can be productively discussed—both with the people whose adversarial or anguished arguments chemists react to, and with the chemists’ exaggerated and defensive response to them. The facts remain that the industries that transform matter (to which chemistry is central) have flourished to an extent that is staggering. They’ve played an essential material role in prolonging life, and while not making people any happier, they have provided spiritual value. The value I’m thinking of is not in creating the materials for CDs and books, ancillary tools to spiritual satisfaction, but in providing partial, yet unprecedented knowledge of the world. And the transformative industries are also responsible for an immense quantity of hazardous waste. The scale of their fecund creative enterprise is such that the major cycles of the world are perturbed. More than half the N and S atoms in our bodies have seen the inside of a chemical factory. And C, O, and H atoms too, through agriculture, food preparation, and sewage treatment.

Qualitative Thinking in the Age of Modern Computational Chemistry, or What Lionel Salem Knows

The achievements of modern computational chemistry are astounding. It is reasonable today to handle billions of configurations, and to achieve chemical accuracy, kilocalories say, in calculating binding energies and geometries, in ground and transition states of reasonably complex molecules. There is no question that the enterprise of computational theoretical chemistry is successful. Now Lionel Salem and I grew up and developed scientifically in the climate of the very same computer which made all this possible. Russ Pitzer taught me to punch cards; I still miss the sound of the key punch. The extended Hückel method, which several of us developed in the Lipscomb group, would have been impossible without modern computers. But I took a different turn, moving from being a calculator in the framework of semiempirical theory, to being an explainer, the builder of simple molecular orbital models. I was and am still doing calculations, but my abiding interest is in the construction of explanations. And also in thinking up moderately unreasonable things for experimentalists to try. In existing as a scientist, meaning that my work was of continuing interest to other chemists, I was helped in that I moved into whatever part of chemistry I did, just a little ahead of the heavy guns of computational chemistry. So I switched from organic to inorganic molecules just when organic molecules became reasonably calculable. Recently I’ve been less fortunate, for when I moved to solids and surfaces I came back into heavy fire—physicists had been doing calculations on these materials for a long time. And they were (are) hardly likely to believe that one-electron calculations and a chemical viewpoint are of value. I want to make some observations on computational quantum chemistry, perforce influenced by my prejudices. Given the advances in the field, any molecule I can calculate (without geometrical optimization), with the simplest extended Hückel approximation, can be done so much better by most computational chemists. So why don’t I feel threatened; why is there a role for people of my ilk? Or for Lionel. Actually, I do feel threatened and bypassed! But that’s just an emotional reaction, and my aging figures in it.

What Might Philosophy of Science Look Like If Chemists Built It?

Implicit in the title might be two presumptions. The first one, that there is (or should be) a single philosophy of science, is not a claim I intend—I do think one should look for a common core, in a way that allows for differences. The second presumption, that philosophy of science, as it is construed today, would be different if it were based on chemistry, is what I wish to examine. And behind that latter supposition is the notion that philosophers of science, their professionalism and good will not impugned, nevertheless are likely to construct their worldview of science based on the sciences they know best. These are usually the sciences that they studied (a) as a part of their general education, or (b) the science they came from, so to speak, if they made their transition to philosophy at some later point in their career. I have not made a rigorous examination of the education of philosophers of science. But my anecdotal feeling is that, for those who entered the profession directly, an exposure to mathematical logic is more likely than to geology or chemistry. And, for many of the philosophers of science who came to their field after an initial scientific career, their scientific expertise was likely to be in the first instance physics, after that biology, and rarely chemistry. I will argue that this matters, for chemistry is different. There are exceptions. In the English-writing community, the most striking one is Michael Polanyi, a very distinguished physical chemist. In the French philosophical community, Pierre Duhem, Emile Meyerson, Gaston Bachelard, and Hélène Metzger had professional chemical backgrounds. Bernadette Bensaude-Vincent has argued convincingly that this background shaped their philosophical outlook, in contrast with the analytic philosophers of their time. In recent times the situation may have changed. A subfield of “philosophy of chemistry” has emerged, with annual meetings and two journals (Foundations of Chemistry, Hyle). The practitioners of this field are more likely to have had substantive experience in chemistry.

Why Buy That Theory?

The theory of theories goes like this: A theory will be accepted by a scientific community if it explains better (or more of) what is known, fits at its fringes with what is known in other parts of our universe, and makes verifiable, preferably risky, predictions. Sometimes it does go like that. So the theory that made my name (and added to the already recognized greatness of the man with whom I collaborated, the synthetic chemist of the 20th century, R. B. Woodward) did make sense of many disparate and puzzling observations in organic chemistry. And “orbital symmetry control,” as our complex of ideas came to be called, made some risky predictions. I remember well the day that Jerry Berson sent us his remarkable experimental results on the stereochemistry of the so- called 1,3-sigmatropic shift . It should proceed in a certain way, he reasoned from our theory—a non-intuitive way. And it did. But much that goes into the acceptance of theories has little to do with rationalization and prediction. Instead, I will claim, what matters is a heady mix of factors in which psychological attitudes figure prominently. A simple equation describing a physical phenomenon (better still, many), the molecule shaped like a Platonic solid with regular geometry, the simple mechanism (A→B, in one step)—these have tremendous aesthetic appeal, a direct beeline into our soul. They are beautifully simple, and simply beautiful. Theories of this type are awesome in the original sense of the word—who would deny this of the theory of evolution, the Dirac equation or general relativity? A little caution might be suggested from pondering the fact that political ads patently cater to our psychobiological predilection for simplicity. Is the world simple? Or do we just want it to be such? In the dreams of some, the beauty and simplicity of equations becomes a criterion for their truth. Simple theories seem to validate that idol of science, Ockham’s Razor. In preaching the poetic conciseness and generality of orbital explanations, I have succumbed to this, too.

Some Heretical Thoughts on What Our Students Are Telling Us

There is a time, twice a year, when those of us who teach introductory courses sit down in a comfortable chair, pour ourselves a middling portion of single malt Scotch whisky, and begin to read the comments that students write about our teaching. For the overall ratings, numerical in nature, we can bear to wait—the computer will dutifully compile these single point undifferentiating indicators. What we settle down to read are the “free-style comments,” where the students are encouraged to write (anonymously, of course) what they think of the book, the exams, and, of course, of the lecturer. Many, not all, universities give students the opportunity to express themselves in this way. Some of us have learned to avoid asking silly questions with predictable responses, such as “What is the best part of the course?” So we sit down, perhaps turning on some Chopin to complement the whisky, and face those student responses. Many are positive, as (with a trace of mild astonishment) “I didn’t think I’d like chemistry, but Prof. Coppola made it fun!,” “I actually enjoyed going to the lectures,” or “I didn’t get a very good grade, but I sure learned a lot.” It’s not always easy for a student (or us) to say a word of praise, to give thanks graciously harder still. Positive feelings generally wash over us leaving small marks. Happiness is often diffuse. But pain is sharp—the small pain of a torn cuticle, the stronger incapacitating pain of a broken bone. Or, negating the validity of the familiar litany “sticks and stones . . . ” the mental anguish of reading an evaluation such as “Prof. Hoffmann spends all his time on digressions, relating chemistry to politics, history, God knows what else. Who cares how hemoglobin or catalytic converters work? I want to know what’s on the MCATs.” Or “I got an A by memorizing equations and doing exam problems that were exactly like the problems that I had seen on the previous tests . . . ” Or, “As far as I am concerned I did not need to go to class.”

Molecular Beauty

My wife and I were on our way to Columbus, Ohio. After I settled on the airplane, I took out a manuscript I was working on—typical for the peripatetic obsessive chemist. Eva glanced over and asked, “What are you working on?” I said: “Oh, on this beautiful molecule.” “What is it that makes some molecules look beautiful to you?” she asked. I told her, at some length, with pictures. And her question prompted this essay. What follows is an empirical inquiry into what one subculture of scientists, chemists, call beauty. Without thinking much about it, there are molecules that an individual chemist, or the community as a whole, consider to be the objects of aesthetic admiration. Let’s explore what such molecules are, and why they are said to be beautiful. In the written discourse of scientists, in their prime and ritual form of communication, the periodical article, they’ve by and large eschewed emotional descriptors. Even ones as innocent as those indicating pleasure. So it is not easy to find overt written assertions such as “Look at this beautiful molecule X made.” One has to scan the journals for the work of the occasional courageous stylist, listen to the oral discourse of lectures, seminars, the give-and-take of a research group meeting, or look at the peripheral written record of letters of tenure evaluation, eulogies or award nominations. There, where the rhetorical setting seems to demand it, the scientist relaxes. And praises the beautiful molecule. By virtue of not being comfortable in the official literature—in the journal article, the textbook or monograph—aesthetic judgments in chemistry, largely oral, acquire the character of folk literature. To the extent that the modern-day subculture of chemists has not rationally explored the definition of beauty, these informal, subjective evaluations of aesthetic value may be inconsistent, even contradictory. They are subfield (organic chemistry, physical chemistry) dependent, much like the dialects, rituals or costumes of tribal groups. In fact the enterprise of excavating what beauty means in chemistry seems to me to have much of the nature of an anthropological investigation.

How Symbolic and Iconic Languages Bridge the Two Worlds of the Chemist: A Case Study from Contemporary Bioorganic Chemistry

Chemists move habitually and with credible success—if sometimes unreflectively—between two worlds. One is the laboratory, with its macroscopic powders, crystals, solutions, intractable sludge, things which are smelly or odorless, toxic or beneficial, pure or impure, colored or white. The other is the invisible world of molecules, each with its characteristic composition and structure, its internal dynamics and its ways of reacting with the other molecules around it. Perhaps because they are so used to it, chemists rarely explain how they are able to hold two seemingly disparate worlds together in thought and practice. And contemporary philosophy of science has had little to say about how chemists are able to pose and solve problems, and in particular to posit and construct molecules, while simultaneously entertaining two apparently incompatible strata of reality. Yet chemistry continues to generate highly reliable knowledge, and indeed to add to the furniture of the universe, with a registry of over ten million well-characterized new compounds. The philosophy of science has long been dominated by logical positivism, and the assumptions attendant upon its use of predicate logic to examine science, as well as its choice of physics as the archetype of a science. Positivism thus tends to think of science in terms of an axiomatized theory describing an already given reality and cast in a uniform symbolic language, the language of predicate logic. (See especially the locus classicus of this position, Carnap’s book.) The authors of this paper wish to question certain positivist assumptions about scientific rationality, based on an alternative view brought into focus by the reflective examination of a case study drawn from contemporary chemistry. Our reflections owe something to Leibniz,2a Husserl,2b Kuhn,2c and Polanyi,2d and draw upon the earlier writings of both authors, Hoff mann3a and Grosholz.3b We will offer a nonreductionist account of methods of analysis and synthesis in chemistry. In our view, reality is allowed to include different kinds of things existing in different kinds of ways, levels held in intelligible relation by both theory and experiment, and couched in a multiplicity of languages, both symbolic and iconic.

The Say of Things

In search of a chemical conversation, we are on a farm in Uniow, a little Ukrainian village in Austro-Hungarian Galicia, just before the onset of World War I. In the farm yard we see a big, steaming, lead-lined iron pot. The men have mixed some potash in it (no, not the pure chemical with composition KOH from a chemical supply company, but the real ash from burning good poplar) and quicklime, to a thickness that an egg—plenty of eggs here, judging from the roaming chickens—floats on it. Elsewhere in the yard, women are straining kitchen grease, suet, pig bones, rancid butter, the poor parts skimmed off the goose fat (the best of which had been set to cool, cracklings and all). This mix doesn’t smell good; they would rather toss the kitchen leavings and bones into the great iron pot, but the fat must be free of meat, bones, and solids for the process to work. They are making soap. Not that we had to go that far, near where one of us was born, for soap was prepared in this way on farms from medieval times until the twentieth century. Fat was boiled up with lye (what the potash and quicklime made). The reaction was slow—days of heating and stirring until the lye was used up, and a chicken feather would no longer dissolve in the brew. One learned not to get the lye on one’s hands. The product of a simple chemical reaction was then left in the sun for a week, stirred until a paste formed. Then it was shaped into blocks and set out on wood to dry. And inside the steaming pot, deep inside, where the fat and the lye are reacting? There is the conversation we are after, a hellishly animated molecular conversation. The lye that formed was an alkaline mixture of KOH, Ca(OH)2, and NaOH. In the vat one had hydroxide (OH-) ions, and K+, Ca2+, Na+ all surrounded in dynamic array and disarray by water molecules. Contaminants aside, the fat molecules are compounds called esters, in which an organic base, glycerol, combines with three long-chain hydrocarbon chains.

Trying to Understand, Making Bonds

In 2007, on the occasion of my 70th birthday, Bassam Shakhashiri organized a symposium for me at the Boston meeting of the American Chemical Society. The session was entitled “Roald Hoffmann at 70: A Craftsman of Understanding.” I began my talk with thanks to many. That section has been shifted to the end of this chapter. I was born in a happy young Jewish family in unlucky times, 1937. In that war, most of us perished, 3800 of the 4000 Jews of Złoczów, now Zolochiv in Ukraine. Among those who were killed were my father, three of four grandparents, three aunts, and so on. I just want to show you three photos which relate to that time, one old and two recent. The last 15 months of the war we were hidden by a good Ukrainian man–Mikola Dyuk, the schoolteacher in the small village of Univ. The first year we were in an attic of the schoolhouse, the second year in a storeroom with no windows, maybe 6 x 10 feet, on the ground floor. Here are two photos from 2006, when my sister, my son, and I visited Univ. Here is the attic in which we were hidden, with its one window. The storeroom, a passageway, another ground floor room are gone, rebuilt into a new classroom of Univ’s school. It’s a chemistry classroom. Such is fate. Under the plank floor we dug a bunker to sit in if the police came to the house. I was five and a half when we went in. And nearly seven when we went out. Here’s a photo of me, a few months after we came out. We survived. Some of us. Good people helped us, I tell their story. I am also the speaker for the dead—the three million Polish Jews who were killed do not have good stories to tell, or photos to show. We built a new life, in refugee camps where I read of Marie Curie and George Washington Carver, and then came to America in 1949.

Science and Crafts

I came to Penland to write. The craft s were dear to me; first textiles, especially bobbin lace, which my wife made and collected, and taught me to look at. Then the Japanese ceramics to which Kenichi Fukui and Fred Baekeland introduced me. Followed by the protochemistry of dyeing with indigo from snail and plant sources, to me still the ideal bridge between science and culture. The tribute is to be seen around my house—my children’s inheritance consumed as much by crafts as “high” art. So it was easy to accept an invitation to come to Penland and write. Who knew what would come—I wanted to write poems, perhaps an essay. For the poems I’ve needed nature—not so much to write about as to shake me loose from the everyday worries of the (exciting) daily life I had in Ithaca. Nature was a path to concentration; I expected to find a different nature in the foothills of the Blue Ridge Mountains. I would watch the crafts process. Maybe someone would even let me try something. Or ask me to tell them of the chemistry of their craft. I, in turn, would craft my poems out of the green hills. But this is not what happened; here’s what happened: I walk into Billie Ruth Sudduth’s basketry class, and there’s the whole group dyeing their canes, steaming pots of synthetic dye. I ask someone what they are doing, and she says, “Well, I’m getting ready for the upsetting,” and then seeing the puzzled look on my face, patiently explains this old, wonderfully direct basketry term for bending the canes forming the base of a basket over themselves, so that they stand up. I walk uphill to the iron shop, clearly more of a macho place, watch an intense young man, lawyer become sculptor as it turns out, hammer out a hand on a swage block. Ben tells me that it’s possible to burn away the carbon in the steel, and the iron would “burn” too, oxidize, in too hot a flame.