How We Decide: an Analysis of an Essential Process We Take for Granted

How We Decide: an Analysis of an Essential Process We Take for Granted October 20, 2016

The Mariner IV spacecraft was built with four solar panels. The panels were folded during launch and were to spring out once the spacecraft was in space, but the fragile panels couldn’t be damaged by being abruptly snapped into place. Previous spacecraft had used dampers to control the panels’ motion, but these and other improved dampers were unsatisfactory because they contained oil that could leak or were too heavy or were unreliable. The damping problem became a great concern as the launch date came nearer. Only after investigating what would happen after a complete failure of the damper was it discovered that dampers were in fact unnecessary.

Mariner IV went to Mars in 1964 without solar panel dampers. The lightest and most reliable damper was no damper at all.

Decide decisions

We constantly make decisions in everyday life, but how can we best approach them? Can we improve this familiar process? There are different ways of going about it, some excellent, some atrocious. And that’s what this essay is about.

This is a guest post by long-time commenter Richard S. Russell. Richard is a retired research analyst (Wisconsin Department of Public Instruction); long-time activist in the realms of atheism, science fiction, and liberal politics; ballroom dancer; database developer; and generally highly opinionated person. He blogs irregularly at

Everybody makes hundreds of decisions every day. Some of those are good decisions, some bad, but the great majority are simply routine. You walk into the bathroom early in the morning and, without spending any noticeable time on it, decide to flip on the light switch, something you’ve done so often it’s habitual.

But somewhere along the line, perhaps on the very first morning you woke up in that house, you had to make that light-switch decision for the first time ever. At that point, you invested a little bit of thought in it. This essay is about decisions like that, the kind where you consciously work through the question before arriving at a conclusion.

It’s not about the sort of process that Malcolm Gladwell discussed in detail in his book Blink, wherein people arrive at judgments—often correct ones—in the blink of an eye but can’t articulate how or what led them to their conclusions. What Gladwell glosses over is that his chief examples are of experts in their fields—art critics looking at what purports to be an ancient Greek status but is actually a fake, or a tennis champion who went on to a long career as a coach and TV color commentator being able to predict with uncanny accuracy which of a player’s soft second serves would turn out to be double faults. These are people who have internalized their expertise into their subconscious minds. But I’ll be discussing normal de novo decisions by normal, non-expert people.

The Idea Factory

Let’s think of decision-making as being akin to an industrial plant—an idea factory, if you will—where inputs go thru a process to get turned into outputs. Because I’m mainly interested in the middle part, let’s quickly dispose of the two ends.

Inputs processes outputs


The results of decision-making are things we do, say, think, and believe. Outputs also include several things which occur below (or perhaps outside of) the level of conscious thought: emotions, esthetics, and habits. These are, of course, a vital part of human existence, but they don’t involve conscious thought, so I’m going to skip them.


There are several types of inputs into decisions, each with its own problems.

1. Definitions. Words are labels for concepts. We use words to make it easier to comprehend and manipulate the concepts. That makes it essential that we know which word goes with which concept, and that’s sometimes harder than it sounds. For example, consider the word “light.” It’s perhaps the most versatile word in the English language, with over a hundred meanings, in every possible part of speech. Just in the sciences, it can mean:

  • the opposite of heavy (an adjective, used in mechanics),
  • what a bird does on a limb (an intransitive verb, used in ornithology),
  • a visible form of electromagnetic radiation (a noun, used in optics), or
  • ignite, as with a Bunsen burner (a transitive verb, used in chemistry).

Often the meaning of the word will be clear from context, but it’s always a good idea, when getting into complex, knotty issues with people you might disagree with, to be sure you’ve agreed on a common set of definitions right from the outset.

2. Axioms. These are glorified assumptions. The glory comes from several different sources. Axioms are:

  • universal—they apply everywhere, and everyone agrees on them
  • reliable—no exceptions have ever been observed
  • fundamental—they can’t be explained in terms of anything simpler

Perhaps the best known set of axioms are the five axioms of Giuseppe Peano, from which the entire theory of natural numbers can be derived. Euclid’s axioms and postulates also form the basis for a complete understanding of plane geometry.

However, outside of abstract fields like mathematics and symbolic logic, axioms are very difficult to come by.

3. Ordinary Assumptions. Into absolutely every decision goes at least one assumption (usually many more). Assumptions are notoriously unreliable. You may have heard the old joke about the word “assume,” which is derived from a process which makes an “ass” of “u” and “me.” Yet they are also unavoidable. For example, into every decision you personally make about what course of action you intend to pursue is the assumption that you will be alive to pursue it. In the discussion of processes which follows, we will see that formal logic tries diligently to state its assumptions explicitly, as premises. This is by far the exception; most assumptions are unstated or implicit.

4. Genetics. “You can do anything if you want it bad enough. That is why we see so many people who can fly.” (Elden Carnahan) But you have no wings, so you can’t fly. You have no gills, so you can’t breathe underwater. It’s also likely that your brain is wired in such a way that there are some thoughts that you simply are unable to think. These probably vary from one individual to another, and they’re almost impossible to measure. To some extent, the limitations of genetics can be overcome by diligent training, but some limits imposed on us by nature we can never overcome.

5. Sensations. Sensory input is extremely valuable but also fallible. As part of a demo I use in my database classes, I hold up three pieces of paper, stapled together with a plastic overlay, and ask the class what color each piece of paper is. The top piece appears to be yellow, the middle one looks orange, and the lowest one is green.

At least, that’s the way it looks until I flip up the piece of yellow plastic in front of them, and they’re revealed to be white, pink, and blue.

colored paper

This is just one of many ways in which you might be misled by your senses. Of course, there’s a “but wait” part to the story as well, which is that it was also our senses which gave us the true picture behind the misleading façade. So rigorous attention to detail can produce a substantial improvement on our original casual sensory input. Can we ever be sure it’s perfectly accurate? No.

6. Memories. Your recollections of your own life experiences get hauled out when something trips the trigger of association in your brain that says “Hey, this new thing is like that old thing.” Memories, too, are sometimes unreliable but provide an unavoidable context for your decisions.

7. Testimony, also known as “other people’s memories.” Personal testimony is one of those curious things that has a great reputation which is completely unwarranted. Yet, despite its being colored by the testifier’s expectations and biases, it too serves as a form of input to the decision-making process—just one that we need to be cautious about.

In part 2, we consider the eight ways we process these inputs. Some are good, and some … aren’t.

I used to think I was indecisive,
but now I’m not so sure.
— seen on the internet

Bad decisions make good stories.
— seen on the internet

Image credit: Kosala Bandara, flickr, CC

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  • smrnda

    I was thinking about the assumptions and the ‘reliable’ axiom. Even if a few exceptions have happened, people often still feel the assumption is still ‘reliably true’ but, given biases, it seems like an awful lot of exceptions can happen but the axiom is still taken to hold. Perhaps a factor is the cost of being wrong. Making a call like ‘the store won’t be busy at this time’ will, at worst, waste some time, and even if a person is wrong about half the time, the time lost might not prove significant to challenge the assumption. So maybe an issue is, people aren’t so great at finding out what’s really true, because we can afford to be wrong quite a lot, as long as we aren’t terribly wrong?

    • TheNuszAbides

      So maybe an issue is, people aren’t so great at finding out what’s really true, because we can
      afford to be wrong quite a lot, as long as we aren’t terribly wrong?

      and the dark side of this heuristic, of course, is privilege-blindness, wherein the dominant/majority lives in such isolation from the marginalized/minority that (barring exceptional efforts to acquire/spread awareness) they fail to grasp terrible wrongs …

  • martin_exp(pi*sqrt(163))

    i’m not sure axioms are easy to come by in mathematics either (especially if they need to be universal, reliable, and fundamental). only in the 19th century did people felt the need to axiomatize the notion of natural numbers, and the view of geometry (and axioms) changed radically, again mostly in the 18th and 19th century. euclid’s axioms are still valid, even if they don’t describe physical space (so are not universal in this sense), and non-euclidean geometries are just alternatives, not exceptions, i think, and thanks to set theory are neither the natural numbers nor euclidian geometry necessarily fundamental.

  • Sophia Sadek

    The other interesting thing about color is that its quality does not actually exist in the physical world. It is a construct of our neural processing network.

    • TheNuszAbides

      new frontier of virtual reality (–> cybernetics, presumably): conveying the vision of [e.g.] various fishes whose optic systems possess more rods & cones than the human system.

  • illa.baker

    Make 90 dollars every day for working on the web from your home office for several h everyday… Get paid each week… You’ll need a laptop, connection to the web, plus a little sparetime…