was at once called in question.

Locke, the empiricist, repudiated all this, and then also made
assumptions which others could not, and cannot, approve. Kant did
something of much the same sort; we cannot regard his "criticism" as
wholly critical.

How can we avoid such errors? How walk cautiously, and go around the
pit into which, as it seems to us, others have fallen? I may as well
tell the reader frankly that he sets his hope too high if he expects to
avoid all error and to work out for himself a philosophy in all
respects unassailable. The difficulties of reflective thought are very
great, and we should carry with us a consciousness of that fact and a
willingness to revise our most cherished conclusions.

Our initial difficulty seems to be that we must begin by assuming
_something_, if only as material upon which to work. We must begin our
philosophizing _somewhere_. Where shall we begin? May we not fall
into error at the very outset?

The doctrine set forth in the earlier chapters of this volume maintains
that we must accept as our material the revelation of the mind and the
world which seems to be made in our common experience, and which is
extended and systematized in the sciences. But it insists that we must
regard such an acceptance as merely provisional, must subject our
concepts to a careful criticism, and must always be on our guard
against hasty assumptions.

It emphasizes the value of the light which historical study casts upon
the real meaning of the concepts which we all use and must use, but