Two metaphors and the places I read them recently made a big
difference to how I look at things.


STEREOSCOPIC VISION

The first one I ran into in Wilfrid Sellars' essay on Philosophy
and the Scientific Image of Man [1]. It's a great essay, talking
about how our everyday picture of the world interacts with our
theoretical, or scientific, picture of the world. The everyday
picture is the one which includes people and their desires, impulses,
reasons, ethics and so on. The scientific picture includes the
things postulated by science - electrons, quarks, electromagnetic
fields, benzene molecules and so on. The two pictures are related
by a great metaphor of stereoscopic vision, with each 'eye', the
everyday eye and the theoretical eye, giving a partial image which
is combined to give the whole picture. I like this a lot since it's
such a vivid metaphor, and when programming or doing physics now I
often find myself thinking that I have my non-theoretical eye closed
so I'm missing some perspective.

In the essay the 'everyday' image is called the manifest image and
the 'theoretical' image is called the scientific image. The essay
discusses the relationship between the manifest and scientific image
in a lot more detail; in particular their jobs aren't completely
symmetrical, with the scientific image needing the manifest image
to get going but ultimately challenging its validity (if there are
only electrons are there reasons?). In a way the everyday story of
the world and scientific story of the world are very different kinds
of story - certainly the scientific story is much more theoretically
loaded - so the stereoscopic vision metaphor in which they are just
two images could be a bit misleading. But all the same the metaphor
and the whole essay in fact has really affected how I look at things
on a daily basis.

It sounds silly but reading the essay and the stereoscopic vision
metaphor in particular got me much more interested in reading
history, reading the news, trying to learn about politics...  Not
that the essay pushes any of this, but I needed a push and the idea
that I've wilfully had one eye closed for most of my life certainly
gave me one.


PONY AND HARNESSES

The second metaphor I read in Gilbert Ryle's book on Dilemmas. This
is a fantastic little book which is great fun to read both because
it covers some varied and tasty subjects - which include the everyday
vs scientific worlds, Zeno's paradox, and pleasure - and because
Gilbert Ryle writes very beautifully. The book is full of unusual
metaphors but one in particular I found very interesting, which is
taking some everyday concept (like seeing) as a pony and various
theoretical structures we might formalize it with (like theories
of perception) as harnesses. For me the metaphor is very expressive;
I like the idea that an everyday idea is like an animal that is
perfectly happy roaming around on its own; I like that we can try
various theoretical structures/harnesses to understand it, and that
the theoretical structures are both artificial and practically
useful.

Ryle also talks about what happens if you use the wrong harness for
a given animal, or the wrong theoretical structure for a given
everyday concept - unexpected bad behaviour, or a dilemma. This can
happen even if separately the everyday concept and the theoretical
structure are perfectly well behaved; it's the misfit between them
which causes trouble. This situation comes up naturally if we meet
a new everyday concept and try to apply a successful existing
theoretical structure from another area. Even if this leads to
logical trouble it's no bad thing, since we learn something about
the concept and the theory from doing it - and we can hopefully use
the experience to make a better-fitting theory.

This misfit example got me thinking of quantum mechanics, specifically
about trying to force the wavefunction to be some more familiar
sort of thing. It's often taken as perhaps a sort of field (but on
a very high dimensional space) or a something more like a probability
distribution (but complex-valued). These things work great up to a
point and teach us a lot, but ultimately they cause me quite some
mental discomfort from what feel like paradoxes - is the
very-high-dimensional space real or just introduced for calculational
purposes? What exactly are we talking about probabilities of? Sadly
I don't know what else a wavefunction should be though!

Also in programming I think quite often forcing an everyday problem
into one or another paradigm which doesn't suit it can lead to
trouble and my feeling mentally strained or torn. For example I
feel disoriented using objects (you might say object-disoriented)
when there's not much state involved, or when trying to keep up a
more functional style when the problem naturally requires mutating
a lot of data. If my programming problems can be fundamentally
different animals maybe there's no one paradigm/harness which will
fit them all.


[1] http://www.ditext.com/sellars/psim.html