In science, if you know what you are doing, you should not be doing it. In engineering, if you do not know what you are doing, you should not be doing it.
—Richard Hamming
What’s the difference between science and engineering?
Five years ago, I would have said something along the lines of “engineers study known unknowns, scientists study unknown unknowns” (with apologies to Donald Rumsfeld), or made a distinction between expanding the frontiers of knowledge (science) and settling already-explored territory (engineering).
These thoughts seem broadly consistent with what others think. Boston University’s College of Engineering says:
Engineers are not a sub-category of scientists. So often the two terms are used interchangeably, but they are separate, albeit related, disciplines. Scientists explore the natural world and show us how and why it is as it is. Discovery is the essence of science. Engineers innovate solutions to real-world challenges in society. While it is true that engineering without science could be haphazard; without engineering, scientific discovery would be a merely an academic pursuit.
And the National Society of Professional Engineers says:
Science is knowledge based on observed facts and tested truths arranged in an orderly system that can be validated and communicated to other people. Engineering is the creative application of scientific principles used to plan, build, direct, guide, manage, or work on systems to maintain and improve our daily lives.
As I’ve started thinking more about the structure of the modern research system, and what its proper scope and purpose should be, I’ve grown increasingly skeptical of these distinctions. The claim I want to make in this post is that, following the above definitions of engineering, most chemistry is engineering. I don’t think this is bad! In fact, I think that many chemists could benefit from borrowing from an engineering mindset, and should consider incorporating this perspective in their self-conception.
I want to return to the BU and NSPE definitions, because I think they’re concise and well-written, and take as gospel that scientists “explore the natural world and show us how and why it is as it is,” while engineers “innovate solutions to real-world challenges in society” (we’ll revisit issues of definition later). In short, developing something you want other people to use makes you an engineer. Which branches of modern organic chemistry are science, and which are engineering?
Method development—one of my core interests—seems like a good candidate for “engineering.” Researchers in this space identify unsolved problems in organic synthesis, develop methods or catalysts to solve these problems, and then (in many cases) advertise, license, & sell their solutions to consumers! (If you don’t believe me, just look at the “Organic Synthesis” tab of the Sigma-Aldrich Professor Product Portal.) If these products weren’t molecules and were instead mechanical gadgets, nothing about this would be obviously scientific.
And the problems chosen are identified almost purely on the basis of what might be useful to potential users. There’s no clearer illustration of this than the recent gold rush to identify synthetic routes to bicyclic arene bioisosteres, which are useful in medicinal chemistry. Five years ago, I can’t think of a single paper making these compounds; now, I can find nine in high-profile journals just from the past year or so (1, 2, 3, 4, 5, 6, 7, 8, 9).
Mechanistic and physical organic chemistry—another love of mine—present a tougher case, since in most cases the outcome of the studies is only knowledge. But I’m still not sure that this makes this field scientific! Let me illustrate why with an example.
An automotive engineer may be confused by why a given transmission is not working. He/she may formulate a hypothesis, take the transmission apart, perform various experiments on its constituent pieces, validate or disprove the initial hypothesis, and generally conduct a thorough mechanistic investigation to understand the origin of the problem. But does that make him/her a scientist?
The answer, I think, is no. The subject matter is not scientific, so no amount of scientific thinking can make the work science. Similarly, I’d argue that investigating the mechanism of a system invented and developed by humans—like a Pd-catalyzed cross-coupling reaction—doesn’t count as science. (Does application of the scientific method automatically make one a scientist? See below for a continued discussion.)
In contrast, something that I think is a truly scientific area of investigation is the study of enzyme structure and function. Despite extensive study and many Nobel prizes, we’re still learning about how enzymes operate and how they achieve such extraordinary reactivity and selectivity. (For an example of this sort of work, see Arieh Warshel’s review on electrostatic effects in enzyme catalysis, and references therein.)
I don’t think I understand all areas of chemistry well enough to fairly judge whether they’re better understood as engineering or science, so I’ll leave this as an exercise to the reader: What motivates your research? Are you mainly driven by a desire to understand the natural order of things, or do you aim to develop technology to make the world better? Both are important, and neither answer is bad—but if your main goal is inventing a new molecule, material, algorithm, or medicine, you might consider thinking of yourself as more of an engineer than a scientist.
Since the claim that “most chemistry is engineering” is weird, we might consider alternative definitions to solve this problem.
One appealing definition: “a scientist is anyone who uses the scientific method.” As I discussed above, in the case of the automotive engineer, lots of people use the scientific method who clearly aren’t scientists: engineers, yes, but also detectives, doctors, and many other people. Indeed, according to this definition almost anyone who acquires data to shed light on a problem is “doing science.” So I don’t think this is a very good definition.
Another definition might be: “if you’re closely involved with science, you’re a scientist, even if the work you’re doing isn’t literally pushing the frontiers of knowledge forward.” I’m sympathetic to this definition, but I still find it hard to separate scientists and engineers here. What makes an engineer optimizing a new flow reactor less of a scientist than the chemist optimizing a new catalyst? Are they both scientists? What about people who work on chip design and fabrication, or people who design analytical instruments, or people who use them? I can’t find any clean way to divide scientists from engineers that recapitulates the conventional usage of the terms.
I think the root of this confusion is that the nature of scientific fields has changed over the past half-century. Organic chemistry hasn’t always been largely engineering; a century ago, the structure of natural products and the nature of the chemical bond were mysteries, truly the domain of science, and these issues were studied by chemists. As we’ve grown to understand our field better and better, our work has shifted from science to engineering—the true mysteries in chemistry are now few and far between, and the challenge facing today’s chemists is how to use centuries of accumulated knowledge to better society. But because of our lineage, we think of ourselves as scientists, and have managed to disguise the true nature of our work so well that we’ve deceived even ourselves.
By this point, it should be obvious that I don’t think science is superior to engineering. In fact, I’m glad to work in an area that’s largely engineering! But the way that an engineer ought to approach their work is different from the way a scientist ought to approach their work. In writing this piece, I came across a 1996 article by Frederick Brooks, who argued that computer science was better understood as an engineering discipline and defended the importance of this claim:
If our discipline has been misnamed, so what? Surely computer science is a harmless conceit. What’s in a name? Much. Our self-misnaming hastens various unhappy trends.
First, it implies that we accept a perceived pecking order that respects natural scientists highly and engineers less so, and that we seek to appropriate the higher station for ourselves. That is a self-serving gambit, hence dubious….
Second, sciences legitimately take the discovery of facts and laws as a proper end in itself. A new fact, a new law is an accomplishment, worthy of publication…. But in design, in contrast with science, novelty in itself has no merit. If we recognize our artifacts as tools, we test them by their usefulness and their costs, not their novelty.
Third, we tend to forget our users and their real problems, climbing into our ivory towers to dissect tractable abstractions of those problems, abstractions that may have left behind the essence of the real problem.
I think Brooks’s summary is simple and elegant. If we judge the value of our work based on the utility of our tools, rather than the novelty of our ideas, we’ll spend our time on different problems and get excited about different advances. There’s room for both scientists and engineers in chemistry—but at the margin, I think our field would benefit from becoming less like science, and more like engineering.
Thanks to Michael Nielsen, Joe Gair, Ari Wagen, and Michael Tartre for editing drafts of this post. Michael Tartre sent me the Richard Hamming quote, and Phil Brooks sent me his grandfather’s article.