IT remains now, that we discourse a while of the Fourth and last Question, propos’d at the beginning of this Tract; which was, With what Cautions Final Causes are to be Consider’d by the Naturalist?
But the Cases whereto this Question may relate, are so many and so differing, that, what I shall endeavour upon so diffus’d and difficult a Subject, will be rather to point you out some Sea-Marks, that may direct you to shun those latent Rocks, against which divers Learned Men have dash’d; than to present you with a Mariners Compass, and a Sea-Card, that may constantly guide you in the Courses of your Navigation, through so unfrequented a Sea.
And, to make way for what I am to offer by a Distinction, the want of which seems to have contributed to the Obscurity of my Subject; I shall observe to you, that there are two ways of Reasoning from the Final Causes of Natural Things, that ought not to be Confounded. For, Sometimes from the Uses of things Men draw Arguments that relate to the Author of Nature, and the General Ends he is suppos’d to have intended in things Corporeal: As, when from the manifest Usefulness of the Eyes, and all its parts, to the Function of Seeing, Men infer, that at the Beginning of Things the Eye was fram’d by a very Intelligent Being, that had a particular care, that Animals, especially Men, should be furnish’d with the fittest Organ of so necessary a Sense as that of Sight. And Sometimes also, upon the supposed Ends of things Men Ground Arguments, both Affirmative and Negative, about the peculiar Nature of the Things themselves; and Conclude, that This Affection of a Natural Body or Part ought to be granted, or That to be denyed, because by This, and not by That, or by This more than by That, the End design’d by Nature may be best and most conveniently attain’d. This latter sort of Arguments I am wont to call purely or simply, Physical Ones; and those of the former sorts may, for distinctions sake, be styl’d Physico-Theological Ones; or (if we will with Verulamius refer Final Causes to the Metaphysicks,) by a somewhat shorter name, Metaphysical Ones.
What has been premised about these Two Ways of Arguing, allows me to proceed to what I shall venture, tho’ not without much diffidence, to offer you, concerning our Grand Questtion about; which I shall refer my present Thoughts to the Five ensueing Propositions.