Appendix 26. - (299)
[Leibniz and presentiment]
On this subject [of presentiment], Leibniz points out 1. that animals are easily caught because they do not have the ability to draw universal and necessary consequences from things; 2. that empiricists are subject to numerous errors because they rely upon experience alone. Statesmen and leaders, over-reliant on experience, are subject to similar mistakes. Wiser people, besides using experience, attempt to get down to the reason for things in order to judge when it is opportune to make exceptions. Leibniz adds:
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Reason alone is able to lay down sure rules, and provide the missing element for uncertain rules by finding exceptions to them, and finally find certain connections in the power springing from necessary connections. This often provides a means of foreseeing an event without any need to experience the sensible link between images to which beasts are reduced. Indeed that which justifies the internal principles of necessary truths also distinguishes mankind from animals (N. Essais, etc., Preface) |
A comment on this whole argument of Leibniz.
First, the principles of prudence governing a wise person's activity are based upon prevision of certain events, but not upon an absolute prevision or, as the philosophers say, apodictically necessary prevision. In this case, prevision is only relatively or hypothetically necessary. For example, knowing that the nature of the sun is to shine, I foresee that it will shine tomorrow. However, this prevision, although founded upon knowledge of the sun's nature, has no inner necessity. It is true only on the hypothesis that the sun continues in its orbit without undergoing any changes. This could also happen, because it does not involve any contradiction. Leibniz, therefore, confuses apodictic with hypothetical necessity. Only apodictic necessity exhibits the full power of reason because reason owes nothing to the senses for its firm, absolute necessity but it owes it all - let it be said in passing - to the infinite force of an unlimited, supra-sensible truth. Pascal fell into an error somewhat similar to that of Leibniz when, as I have already remarked (Opusc., Fil, 5: 1, p. 93), he included among the first principles of reason, space, time, movement and matter, and affirmed in refuting the Pyrrhonists that knowledge of these things is as solid as any knowledge obtained by rational argument. Space, time, etc., are not principles of reason; they are merely positive data of experience. The principles of reason have an inner necessity; data have an arbitrary character because they are chiefly dependent upon the will of the creator, either to be in one form rather than another, or certainly to be or not to be, and to be the subject of our experiences in some way. In a word, the principles of reason are apodictically necessary; the primary data of experience are hypothetically necessary, that is, constituents of arguments which we make about a certain genus of things because they are given to us as such, not per se. A comparison between Pascal's error and Leibniz's, can be made as follows:
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I. First, the following must be established: |
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1. There are absolute principles of reason, such as the principle of contradiction, which are apodictically certain. |
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2. These principles, when applied to some genera of contingent things produce other principles of hypothetical necessity which should be called primary data. These can be nominated as space, time, motion, and so on. |
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3. Using the principles and primary data, other consequences of a double hypothetical necessity are deduced which require two hypotheses, that is, 1st. data of space, time, etc.; 2nd. data from bodies, etc. |
Pascal confuses the apodictic necessity of principles of reason with the hypothetical necessity of primary data. Leibniz went a step further, and confused the apodictic necessity of principles with the doubly hypothetical necessity.
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II. Moreover, Leibniz's argument is directed at proving that we cannot derive all our cognitions from the senses because they never give us necessary, universal cognitions which we must extract from deep within our reason. This may be proved not only by necessity mingled with our reasoning, that is, by merely apodictic necessity, but also by any degree of hypothetical necessity, because the senses can never provide necessity of any kind. Leibniz's argument as a whole, therefore, is on the right lines, but the following partial mistake may be noted. He equated animal with empirical behaviour. This, I maintain, is wrong. Even the behaviour of empirical people is based upon a reason, a principle, which has its own universality and necessity, and to this extent cannot be deduced from the senses. In fact, empirical people are guided in their activity by similar cases; they begin, therefore, from the universal principle of analogy. This principle, although the cause of frequent error, is nevertheless universal or is, at least, taken as such. Empirical people also err by placing too much reliance on experience and unduly widening the scope of its applications: 'This is how it has been, so this is how it is going to be.' But they could not succeed in unduly extending the scope of the results of experience, that is, the universalisation of similar instances, if they relied solely on the senses. They use their reason and add universality and necessity, derived from themselves, to facts. They may indeed err in this, but they do so by transcending the senses and show that they themselves possess a conception of universality and necessity. Beasts do not behave in this way. Without rules, they follow their instinct or habit from which they acquire a tendency and an inclination to repeat certain actions, to prefer some and shun others. The behaviour of even a pragmatist cannot be confused with that of an animal lacking reason. |