Making sense of the world: the need to entertain the inconceivable
An interesting example of the constraints placed on inquiry by stories that make some things difficult to conceive came up in Neurobiology and Behavior last week, during a discussion of the ability of the nervous system to generate outputs by itself rather than simply in response to external stimuli.
"Perhaps I've just had the idea that 'cause equals effect' engrained in my mind for so long that it's just difficult to sway me, but I still feel that there must be some input to trigger reactions in our body"
The problem isn't, I think, personal observations. There are lots of situations where a naive observer presumes that things move of their own accord rather than in response to an external perturbation (a sleeping dog wakes up). My guess is the problem has to do instead with the effect stories have on how one makes sense of personal observations.
"A body in motion remains in motion and a body at rest remains at rest unless acted on by an outside force." .... Newton's First Law of Motion (more or less)
Newton's laws were a remarkable were and remain a remarkably successful story, one that accounted for an unusually wide range of observations, and continue to be of enormous value in a particular context. But, like all scientific stories, Newton's laws have limits, and can get in the way of new stories if those limits aren't appreciated.
The presumption that things remain unchanged unless acted on by an outside force dominated psychology for an extended period (the "stimulus/response" paradigm), and clearly is still influential for many students in that realm who will go to great lengths to find a "stimulus." And they are not alone. The notion that things might move, or otherwise change, for reasons entirely internal to themselves was actively resisted by scientists in 100 years or so ago in the case of both thermal motion and radioactive emission, cases where the eventual consensus was that Newton's First Law didn't in fact apply: things can indeed change their state in the absence of external causes.
That understanding was hard won. As Oliver Sack's wrote about his own education as a chemist
"I found this profoundly mystifying and disconcerting, that an atom might disintegrate at any time, without any "reason" to do so. It seemed to remove radioactivity ... from the intelligible, causal universe - and to hint at a realm where laws of the classical sort meant nothing whatsoever." (Uncle Tungsten, p284)
And later, in connection with quantum mechanics
"I had looked to chemistry, to science, to provide order and certainty, and now suddenly this was gone. " (Uncle Tungsten, p 311)
Or maybe the stories that become "engrained" do so because they satisfy some inner preference? Maybe Newton's First Law appeals to us because of a taste for "order and certainty"? Whether because of inner taste or because its engrained, we do seem to need a new story ...
"... we know all atoms to perform all the time a completely disorderly heat motion, which, so to speak, opposes itself to their orderly behavior and does not allow the events that happen between a small number of atoms to enrol themselves according to any recognizable laws. Only in the co-operation of an enormously large number of atoms do statistical laws begin to operate ... All the physical and chemical laws that are known to play an important part in the life of organisms are of this statistical kind ..." Erwin Schrödinger, What Is Life?, 1944
Bodies at rest unless acted on by an outside force is in the contemporary version of this story not a starting point but instead a problem that requires explanation. The starting point is .... continual change not attributable to any particular external agent. For more on this sort of story see Inverting the relationship between randomness and meaning, Alternate perspectives on randomness and its significance, and On beyond an algorithmic universe.
As for the nervous system, see Yes, signals can start in the middle of the box. And it is well worth thinking about what aspects of behavior one might be able to better make sense of from this rather than a reflex point of view.