Philosophy can exclude nothing.
...before the work of systematization commences, there is a previous task—a very necessary task if we are to avoid the narrownesses inherent in all finite systems... [this] primary stage can be termed 'assemblage'.
...the philosophic process of assemblage should have received some attention from every educated mind, in its escape from its own specialism.
In Western Literature there are four great thinkers, whose services to civilized thought rest largely upon their achievements in philosophical assemblage; though each of them made important contributions to the structure of philosophic system. These men are Plato, Aristotle, Leibniz, and William James.
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William James, essentially a modern man. His mind was adequately based upon the learning of the past. But the essence of his greatness was his marvellous sensitivity to the ideas of the present. He knew the world in which he lived, by travel, by personal relations with its leading men, by the variety of his own studies. He systematized; but above all he assembled. His intellectual life was one protest against the dismissal of experience in the interest of system. He had discovered intuitively the great truth with which modern logic is now wrestling.
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One characteristic of the primary mode of conscious experience is its fusion of a large generality with an insistent particularity.
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In order to acquire learning, we must first shake ourselves free of it. We must grasp the topic in the rough, before we smooth it out and shape it. For example, the mentality of John Stuart Mill was limited by his peculiar education which gave him system before any enjoyment of the relevant experience. Thus his systems were closed. We must be systematic; but we should keep our systems open. In other words, we should be sensitive to their limitations. There is always a vague 'beyond', waiting for penetration in respect to its detail.
--- Whitehead.
https://brocku.ca/MeadProject/Whitehead/Whitehead_1938/1938_01.html