Nobody can reproach psychology with having discovered too few facts. A psychologist who knew
all the facts that have been brought to light by experimental methods would indeed know much,
very much. And such knowledge is today regarded as an aim in its own right. "Find facts, facts, and
again facts; when you are sure of your facts try to build theories. But your facts are more
important." This slogan expresses the creed of a philosophy which is widely accepted today. And
indeed it seems very plausible. On the one side are the objective facts, independent of the
scientist who investigates them; on the other are Ills hypotheses, his theories, pure products of his
mind. Naturally we should attribute more value to the former than to the latter. In psychology
such a view can claim a particular justification. For this science consisted of a number of simple
and comprehensive theories and few scientifically, established facts before the beginning of the
new era. With the advent of experiment more and more facts were discovered which played
havoc with the old theories. Only when psychology determined to become a fact-finding science
did it begin to become a real science. From the state in which it knew little and fancied a great
deal it has progressed to a state where it knows a lot and fancies little - at least consciously and
with a purpose, though unawares it contains more fancy than many psychologists are aware of. To
evaluate this progress we have to examine what it means to know much. The Latin adage multum
non multa distinguishes between two meanings of the word "much." The one which it discards in
favour of the other is purely quantitative. According to the latter a person who knows twenty
items knows ten times as much as the person who knows only two items. But in another sense the
latter person, if he knows those two items in their intrinsic relation, so that they are no longer two
but one with two parts, knows a great deal more than the former, if he knows just twenty items in
pure aggregation. Although from the point of multa this person would be superior, he would be
inferior from the point of multum.
Now as I look upon the growth of science it seems to me that it began to find itself and thereby
entered a new epoch when at the time of the Renaissance it changed from a chase for the multa
to a search for the multum. Since that time science has continually striven to reduce the number
of propositions from which all known facts can be derived. In this enterprise it has been more and
more successful, and has by its new method also discovered more and more facts which otherwise
would never have become known; it has simultaneously discarded as fancy many a piece of
knowledge which was taken as fact, and has changed the systematic status of many other facts. It
is a "fact" that heavy bodies fall more quickly than light ones, as anyone can test by dropping a
pencil and a sheet of paper. But it is a complex, not a simple fact, whereas the simple fact is that
all bodies fall with the same velocity in a ,vacuum. From this scientific fact the everyday fact can be
derived but not vice versa. The very concept of fact, therefore, becomes problematical.