objects are constructed, created out of the formal presuppositions of objectivity in general) and, later, the methods of mathematical physics become the guide and the touchstone of philosophy, the knowledge of the world as a totality The question why and with what justification human reason should elect to regard just these systems as constitutive of its own essence(as opposed to the given, alien, unknowable nature of the content of those systems)never arises. It is assumed to be self-evident. Whether this assumption is expressed(as in the case of Berkeley and Hume)as scepticism, as doubt in the ability of our knowledge to achieve universally valid results, or whether(as with Spinoza and Leibniz) it becomes an unlimited confidence in the ability of these formal systems to comprehend the"true' essence of all things, is of secondary importance in this context. For we are not concerned to present a history of modern philosophy, not even in crude outline. We wish only to sketch the connection between the fundamental problems of this philosophy and the basis in existence from which these problems spring and to which they strive to return by the road of the understanding. However, the character of this existence is revealed at least as clearly by what philosophy does not find problematic as by what it does. At any rate it is advisable to consider the interaction between these two aspects. And if we do put the question in this way we then perceive that the salient characteristic of the whole epoch is the equation which appears naive and dogmatic even in the most critical philosophers, of formal, mathematical, rational knowledge both with knowledge in general and also with ourknowledge Even the most superficial glance at the history of human thought will persuade us that neither of the two equations is self-evidently true under all circumstances. This is most obviously apparent in the origins of modern thought where it was necessary to wage prolonged intellectual wars with the quite differently based thought of the Middle Ages before the new method and the new view of the nature of thought could finally prevail. This struggle, too, can obviously not be portrayed here. a familiarity with its dominant motifs can be assumed. These were the continuity of all phenomena(in contrast to the medieval distinction between the world beneath' the moon and the world it) the demand for phenomena from some transcendental point (astronomy versus astrology ) the demand that mathematical and rational categories should be applied to all phenomena(in contrast to the qualitative approach of nature philosophy which experienced a new impetus in the Renaissance-Bohme. Fludd etc - and even formed the basis of Bacon's method It can similarly be taken as read that the whole evolution of philosophy went hand in hand with the development of the exact sciences. These in turn interacted fruitfully with a technology that was becoming increasingly more rationalised, and with developments in production. 4 These considerations are of crucial importance for our analysis. For rationalism has existed at widely different times and in the most diverse forms, in the sense of a formal system whose unity derives from its orientation towards that aspect of the phenomena that can be grasped by the understanding, that is created by the understanding and hence also subject to the control, the predictions and the calculations of the understanding. But there are fundamental distinctions to be made, depending on the material on which this rationalism is brought to bear and on the role assigned to it in the comprehensive system of human knowledge and human objectives. What is novel about modern rationalism is its increasingly insistent claim that it has discovered the principle which connects up all phenomena which in nature and society are found to confront mankind. Compared with this, every previous type ofobjects are constructed, created out of the formal presuppositions of objectivity in general) and, later, the methods of mathematical physics become the guide and the touchstone of philosophy, the knowledge of the world as a totality. The question why and with what justification human reason should elect to regard just these systems as constitutive of its own essence (as opposed to the ‘given’, alien, unknowable nature of the content of those systems) never arises. It is assumed to be self-evident. Whether this assumption is expressed (as in the case of Berkeley and Hume) as scepticism, as doubt in the ability of ‘our’ knowledge to achieve universally valid results, or whether (as with Spinoza and Leibniz) it becomes an unlimited confidence in the ability of these formal systems to comprehend the ‘true’ essence of all things, is of secondary importance in this context. For we are not concerned to present a history of modern philosophy, not even in crude outline. We wish only to sketch the connection between the fundamental problems of this philosophy and the basis in existence from which these problems spring and to which they strive to return by the road of the understanding. However, the character of this existence is revealed at least as clearly by what philosophy does not find problematic as by what it does. At any rate it is advisable to consider the interaction between these two aspects. And if we do put the question in this way we then perceive that the salient characteristic of the whole epoch is the equation which appears naïve and dogmatic even in the most ‘critical’ philosophers, of formal, mathematical, rational knowledge both with knowledge in general and also with ‘our’ knowledge. Even the most superficial glance at the history of human thought will persuade us that neither of the two equations is self-evidently true under all circumstances. This is most obviously apparent in the origins of modern thought where it was necessary to wage prolonged intellectual wars with the quite differently based thought of the Middle Ages before the new method and the new view of the nature of thought could finally prevail. This struggle, too, can obviously not be portrayed here. A familiarity with its dominant motifs can be assumed. These were the continuity of all phenomena (in contrast to the medieval distinction between the world ‘beneath’ the moon and the world ‘above’ it); the demand for immanent causal connections in contrast to views which sought to explain and connect phenomena from some transcendental point (astronomy versus astrology); the demand that mathematical and rational categories should be applied to all phenomena (in contrast to the qualitative approach of nature philosophy which experienced a new impetus in the Renaissance – Böhme, Fludd, etc. – and even formed the basis of Bacon’s method. It can similarly be taken as read that the whole evolution of philosophy went hand in hand with the development of the exact sciences. These in turn interacted fruitfully with a technology that was becoming increasingly more rationalised, and with developments in production. [4] These considerations are of crucial importance for our analysis. For rationalism has existed at widely different times and in the most diverse forms, in the sense of a formal system whose unity derives from its orientation towards that aspect of the phenomena that can be grasped by the understanding, that is created by the understanding and hence also subject to the control, the predictions and the calculations of the understanding. But there are fundamental distinctions to be made, depending on the material on which this rationalism is brought to bear and on the role assigned to it in the comprehensive system of human knowledge and human objectives. What is novel about modern rationalism is its increasingly insistent claim that it has discovered the principle which connects up all phenomena which in nature and society are found to confront mankind. Compared with this, every previous type of rationalism is no more than a partial system