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Samuel Clarke on arguing a priori

Juan Gomez writes…

In my two previous posts I explored Butler’s preferred methodology in the Analogy and the Sermons. We first looked at bishop Halifax’s description of Butler’s work and then we reviewed the latter’s own methodological statements. Both Butler and Halifax describe two methods used in arguing for the existence and attributes of God: a posteriori and a priori. They identify the latter of these methods with the work of Samuel Clarke. Since we have already discussed at some length Butler’s methodology, I want to spend this post analysing the comments Clarke (one of the leading Newtonians of the first decades of the eighteenth century) makes regarding his use of the a priori method.

Clarke was sympathetic to the experimental method as practised by Newton and he was especially interested in the application of mathematics to metaphysics, which is the project carried out in his Boyle lectures, A Demonstration of the being and attributes of God (1704) and A discourse concerning the unchangeable obligations of natural religion (1705). In the text of the lectures themselves there is not much regarding methodology, other than Clarke stating that his method is “as near to Mathematical as the nature of such a Discourse would allow.” However, subsequent editions of the discourse included Clarke’s replies to objections where in his answers to the sixth and seventh letters he explains in more detail his use of the a priori method. In the former he briefly explains why he prefers it by contrasting it with the a posteriori method:

    The Proof a posteriori is level to All Mens Capacities: Because there is an endless gradation of wise and useful phænomena of Nature, from the most obvious to the most abstruse; which afford (at least moral and reasonable) Proof of the Being of God, to the several Capacities of All unprejudiced Men… The Proof a priori, is (I fully believe) strictly demonstrative; but (like numberless Mathematical Demonstrations,) capable of being understood by only a few attentive Minds; because ’tis of Use, only against Learned and Metaphysical Difficulties

So on one hand the a posteriori proof is accessible to more people, but it provides only reasonable (not demonstrable) proof; on the other, the a priori way of arguing provides demonstrative proof, but it is only reserved for a few minds engaged in metaphysical disputations. Clarke prefers the a priori method in this case (i.e. in natural theology) because it can provide him with demonstrative proof of the attributes of God. However, this method is not meant to be in direct opposition to the a posteriori method, but rather complement it. This is what Clarke mentions in his preface to the Discourse:

    The Honourable Robert Boyle, Esq; was a Person no less zealously solicitous for the propagation of true Religion, and the practice of Piety and Virtue; than diligent and successful in improving Experimental Philosophy, and in inlarging our Knowledge of Nature. And it was his settled Opinion, that the advancement and increase of Natural Knowledge, would always be of Service to the Cause and Interest of true Religion, in opposition to Atheists and Unbelievers of all sorts… In pursuance of which End I endeavoured, in my former Discourse [the Demonstration], to strengthen and confirm the Arguments which prove to us the Being and Attributes of God, partly by metaphysical Reasoning, and partly from the Discoveries (principally those that have been late made) in Natural Philosophy.

Clarke believes that both ways of arguing complement each other and both prove the attributes of God. In his Answer to the Seventh Letter Clarke justifies in more detail his use of the a priori method. Clarke believes that an a priori argument is necessary to carry further what the a posteriori argument proves. He recognizes that the latter “ought always to be distinctly insisted upon,” but the a priori argument is useful to answer objections against the attributes of God at a metaphysical level. Further, Clarke explains that the a posteriori argument by itself cannot prove the eternity, infinity and unity of God:

    The Temporary phænomena of nature, prove indeed demonstrably a posteriori, that there is, and has been from the beginning of those phænomena, a Being of Power and Wisdom sufficient to produce and preserve those phænomena. But that This First Cause has existed from Eternity, and shall exist to Eternity, cannot be proved from those Temporary phænomena; but must be demonstrated from the intrinsick Nature of Necessary-Existence.

In a similar vein, Clarke comments that from the observation of the phænomena of nature we can only prove that there is a Being with sufficient power and wisdom, but not that such being is absolutely infinite and universal. What I want to point out here is that the two methods in consideration should be interpreted as complementary and not as opposed to each other. However, Clarke’s a priori arguments regarding the attributes of God were widely criticized, even from those who shared his Newtonianism and admired the mathematical method that Newton successfully applied in his natural philosophy. One of these critics is Joseph Butler, and in my next post I will examine the discussion between this two figures regarding the attribute of infinity.

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