In Plato's divided line, the ways of "knowing" are imagination, belief, reasoning, and intellectual intuition. The objects that correspond are images of actual things in the world, temporal objects themselves, mathematical objects, and the Forms. Even mathematical truths require postulates, reasonable assumptions, to discover them, and therefore are less certain than the Forms. Even temporal objects can be spoken of with conditional correctness, and therefore there is such a thing as right belief or opinion. Plato argues that we have to know the Forms, in some sense, in order to make sense of the world, which reflects them in the natural and moral order. However, we have to "ascend out of the cave", through dialectic, in order to see them clearly, rather than through the temporal world.
Aristotle thinks that we generalize from sensory perception, amd that only what is axiomatic in logic and mathematics is prior to abstraction. To Aristotle, the Forms are identical with the essences of natural objects, that is, plants, animals, man, the earth, the moon, the sun and planets, and the sphere of the fixed stars. God is, as it were, the summary of the natural order, pure actuality, "thought thinking itself", and exists outside of the material cosmos. He is the Prime Mover because the yearning of the sphere of the fixed stars for perfection causes it to rotate in a never to be satisfied search for pure actuality. Each lower sphere similarly is drawn by the greater perfection of the next sphere. We can never comprehend the way that God does, but we can learn through the manifestation of the natural order in matter, and therefore see the Forms through empirical investigation. His successor at the Lyceum, for example, spent a lot of time systematizing botanical observations.
The Stoics followed Heraclitus in believing that the primary material of the universe was Fire (energy), and that the Logos bound things together in a coherent pattern. The purpose of life was to emulate Nature in becoming indifferent to fortune, to do one's duty, and to discern the order of nature from studying it. The Epicureans believed that everything was composed of atoms in various configurations, that the universe was basically random, and that the purpose of life was the avoidance of pain, including the pain of desire. Moderation and the pursuit of aesthetic and intellectual pleasures seemed to them the Good Life.
The scholastics exhibited a range of opinion, but it is true that a modified Aristotelianism, mainly shaped by Aquinas, was dominant. Aquinas believed that there were truths about God accessible to reason, but that they were inferior to the full array of truths available through revelation.
Descartes started from the standpoint of doubt, and noted that he could not doubt his own existence. After that, he thought that clear and distinct ideas would yield truth, and that the order of nature would prove to be mathematical. Spinoza attempted to set forth the basic truths of philosophy by emulating Euclid's method of setting forth fundamentals and building up proofs in geometry. He considered God to be infinite in His attributes, but manifested to us through two of them, thought and extension. Thus, in a manner of speaking we could know God through reason and the examination of nature, which he supposed to be logical and based on a few premises. Leibniz thought that there would come a time when we had reduced truth to a finite set of elementary propositions which, when combined according to fixed rules, would yield the full array of true propositions.
Bacon was the first to set forth a primitive version of the scientific method. He wanted to set forth a program of research to amass facts about the natural world, through tests and comparisons rather than passive observation, that would yield data for synthesis. His interest was practical, his maxim "Nature to be commanded must be obeyed". Locke did think that we derived conditional knowledge from experience, but the main uncertainty was about the true nature of the objects presented to the senses. Since qualities such as color, though stimulated by the object, do not per se inhere in objects, but are the way we register things according to our mode of perception, it is questionable that we can know much about the absolute nature of things.
Berkeley basically argued against the notion of Prime Matter. It was commonly held that the essences and attributes of things were impressed in Prime Matter, which would otherwise be formless, except for extension. Berkeley argued that "ideas", by which he meant perceptions, like color and shape, were supported by the mind, and did not require Prime Matter. However, since some mind must be perceiving them for them to continue in existence, God must be constantly supporting the existence of the world of objects. Hume argued that what was derived from the senses was opaque, except for a certain common sense utility, and that what was derived purely from reason had no important relationship to the natural world. This was seen as an attack upon the very idea of causality, and therefore of the world described by Newtonian mechanics.
I already described something about Kant. In this context, the important thing to remember is that the world of appearances is constituted by the mind in the act of consciousness, which supplies the logical rules through which appearances relate. Thus, causality is given as the way that way that phenomena relate to one another.
The radical distinction between things- in- themselves and phenomena made by Kant was unsatisfactory. After all, Kant supposes that things materially contribute to our perceptions, which is why we experience a common world. Thus, it must be that things are revealed to a greater or lesser extent in phenomena. In other words, phenomena are revealing, not opaque. Hegel used this insight to examine the development of phenomena in consciousness, in an attempt to show that there was progressive revelation, both historically and in the individual consciousness, and therefore a hypothetical endpoint where all that is rational about the object is comprehended. He argued that the standpoint of absolute knowledge was possible at his historical juncture, because history had essentially fulfilled itself. (Absolute knowledge is not comprehensive knowledge, but knowledge that is not conditional). Thus, we could discern the internal meaning of history, and eventually nature as well, as the thing- in- itself revealed itself fully to the developed consciousness. |
