hing is an
inference, and in fact a very doubtful one. The more such inferences are
examined, the more precarious they are seen to be. Hence the study of
animal behaviour has been gradually led to abandon all attempt at mental
interpretation. And it can hardly be doubted that, in many cases of
complicated behaviour very well adapted to its ends, there can be no
prevision of those ends. The first time a bird builds a nest, we can
hardly suppose it knows that there will be eggs to be laid in it, or
that it will sit on the eggs, or that they will hatch into young birds.
It does what it does at each stage because instinct gives it an impulse
to do just that, not because it foresees and desires the result of its
actions.*

* An interesting discussion of the question whether
instinctive actions, when first performed, involve any
prevision, however vague, will be found in Lloyd Morgan's
"Instinct and Experience" (Methuen, 1912), chap. ii.

Careful observers of animals, being anxious to avoid precarious
inferences, have gradually discovered more and more how to give
an account of the actions of animals without assuming what we call
"consciousness." It has seemed to the behaviourists that similar methods
can be applied to human behaviour, without assuming anything not open
to external observation. Let us give a crude illustration, too crude for
the authors in question, but capable of affording a rough insight into
their meaning. Suppose two children in a school, both of whom are asked
"What is six times nine?" One says fifty-four, the other says fifty-six.
The one, we say, "knows" what six times nine is, the other does not. But
all that we can observe is a certain language-habit. The one child has
acquired the habit of saying "six times nine is fifty-four"; the other
has not. There is no more need of "thought" in this than there is when
a horse turns into his accustomed stable; there are merely more numerous
and complicated habits. There is obviously an observable fact called
"knowing" such-and-such a thing; examinations are experiments for
discovering such facts. But all that is observed or discovered is a
certain set of habits in the use of words. The thoughts (if any) in the
mind of the examinee are of no interest to the examiner; nor has the
examiner any reason to suppose even the most successful examinee capable
of even the smallest amount of thought.

Thus what is called "knowing," in the sense in wh