If you are lost in the middle of the woods, you have a problem.

Assuming that you’ve ended up in this predicament without any navigational aids or food, you’ll have to start walking. Any direction is better than none: if you stay put, you’ll starve. And, once you pick a direction, you better keep going: if you keep changing your mind, you’ll just go in circles, and you’ll starve. Your problem, aside from the lack of food and abundance of predators, is in deciding which way to go: if all your options look the same, how are you supposed to decide?


That little parable is found in Descartes’ Discourse on the Method (1637). It’s an example of an old paradox of rationality and the difference between thought and action: How is it possible to behave rationally when there is no obvious reason to prefer one option over another? While sitting comfortably at your desk, you might ponder this difficulty at length. If you’re stranded in the woods and night is coming, it’s time to haul ass.

Otto Neurath, the polymath Austrian philosopher, proposed a solution to the problem in a paper titled “The Lost Wanderers of Descartes and the Auxiliary Motive” (1913). Imagine there are four wanderers. The first decides, based on her gut instinct, to go west. The second, following a bird he takes to be an omen, goes north. The third scoffs at the irrationality of the first two, weighs all the evidence and eventualities, and heads east, certain that he has made the right decision. The fourth examines the evidence, decides that it is not enough to justify a decision, and draws straws to pick a direction. She goes south.

Neurath condemns the third wanderer for his “pseudo-rationalist” pretensions: in the interest of appearing rational, he has forced a conclusion out of insufficient evidence “on the basis of inadequate premises of whose deficiencies he is unaware.” Even worse, because he thinks he has decided rationally, he is supremely confident in his decision, even though it is no more justified than any other. The hero of the story for Neurath is wanderer number four, who recognizes the limits of her rationality and supplements it with an auxiliary motive—an arbitrary aid to making decisions among options that, rationally speaking, are all equivalent.

As far as Neurath is concerned, the use of an auxiliary motive is not just a good idea — it is unavoidable. Decision making in the real world often requires quick judgments with partial information. Pressed for time and lacking all the facts (if it were even possible to collect all the relevant facts), people routinely draw on auxiliary motives, even when they claim to be acting rationally. Wanderer one uses the hazy guidance of her gut. Wanderer two uses the coincidental flight of a passing bird. Wanderer three, in spite of his claim to rationality, uses an accidental collection of environmental stimuli and half-baked arguments. Wanderer four is Neurath’s hero, because she not only uses an auxiliary motive but recognizes it as one.


Making technology is kind of like being lost in the woods. There are many possible directions to go. If you don’t do anything or keep changing course, you’ll never get anywhere. And, although companies that make it out of the woods may claim to have the secret to success, one tends to suspect that they just picked a direction, got lucky, and justified their decisions after the fact.

However, a popular way of talking about technical decision making that assumes it is supremely rational. Particularly in the case of “high-tech” things like airplanes or computers, we tend to imagine technologies as the result of a series of necessary choices. You may be familiar with montages of failed attempts at flight that show the various ways one should not build an airplane. In this dominant understanding, engineers are not really like our lost wanderers: only one path leads out of the forest, while the others are strewn with the wreckage of wacky almost-planes. Engineering is the science of finding that right path and following it.

This kind of story about engineering is usually preemptive (describing how we’d like technology to be made) or retroactive (justifying decisions that have already been made). When you look at technologies in the making, things are a bit different.

Airplane phylogeny, in Pierre Lemonnier, ed. Technological Choices (p. 408)

What you see when you look at technologies in the making are a tremendous number of choices among similarly plausible options. While the ability of planes to fly is a favorite example of how engineering is fundamentally “true,” there are in fact quite a few ways to design airplanes that will stay in the air. The rational pursuit of technical goals like flight, efficiency, or speed does not explain how engineers choose among options that are equally fast, efficient, or flightworthy.

In short, technical criteria cannot distinguish among all possible cases or tell you precisely what to do next. If you want to know how to make a technical decision or why existing technologies turned out the way they did, simple rationality is not enough: you need to look for auxiliary motives.


Neurath used the parable of the lost wanderers to describe scientific decision making. Given an experimental result, there will always be a number of explanations that are consistent with it. The choice among these hypotheses is underdetermined by the data. That is to say, as a scientist your hypothesis choice is not entirely determined by logic and the data you collect, but also by other things, like what equipment you have available in your lab, what you can get a grant for, or “hot” topics that will land your future article in a big journal. If those examples make auxiliary motives seem unscientific, then we might add Occam’s razor, which is just a classic auxiliary motive for preferring simple explanations over complex ones.

With the growing popularity of “data-driven” or “evidence-based” decision making in companies and government agencies, we are seeing more attempts at rationalizing decisions about technology—making organizations more scientific. However, as Neurath wrote about science, technological decision making is marbled with underdetermination. Potential paths cut every which way through the woods, and auxiliary motives, conscious or not, come into play at every step.

Data and evidence can be very useful, but we must be careful of the pseudo-rationalist assumption that they always point inevitably to a single course of action. Technical rationality alone cannot explain the series of decisions that produce technologies, although some critics and advocates of big-T Technology may pretend it does. Even decisions on the basis of the strongest evidence require auxiliary motives.

Auxiliary motives are not the kinds of things that can just be systematized and added to the model: they are the persistent arbitrariness that lurks just outside of all formal criteria. They are the context and culture that, having been marked as outside our object of interest, keep spilling back in. They are the irrationality that undergirds rationality, the informality that surrounds and supports formality. They are the backdoors and endpoint vulnerabilities of rationally “proven” systems.


This may sound like a depressing take on our ability to design and produce effective technologies. Instead of whiz-bang engineering that speeds us down the rails of progress, we have a bunch of nervous people lost in the woods, drawing straws and looking for omens, unable to make entirely rational decisions. But we can learn to live in the woods.

Living in the woods requires that we decouple the idea that a given technology works from the idea that it is inevitable. People who get lost know that there was always more than one way we could have gone. While the pseudo-rationalists race along self-assuredly straight lines, tripping over roots and crashing into trees, we might move more tentatively, recognizing the limits of our reason and the chancy unpredictability of the forest. We might imitate Neurath’s fourth wanderer, using our auxiliary motives in the open, where they can be revised and shared with others. Instead of seeing the auxiliary motive as a potentially fatal weakness in the armor of technical rationality, we should cultivate it as a necessary resource for action. Because whether we like it or not, life happens in the woods.