But is it true that man has all that he conceives of, or thinks would be useful, and has no “negative evidence of design afforded by the absence of a faculty” to set against the positive evidence afforded by its presence?  He notes that he lacks the faculty of flight, sometimes wants it, and in dreams imagines that he has it, yet as thoroughly believes that he was designed not to have it as that he was designed to have the faculties and organs which he possesses.  He notes that some animals lack sight, and so, with this negative side of the testimony to the value of vision, he is “apt to infer creative wisdom” both in what he enjoys and in what the lower animal neither needs nor wants.  That man does not miss that which he has no conception of, and is by this limitation disqualified from judging rightly of what he can conceive and know, is what the Westminster Reviewer comes to, as follows: 

“We value the constitution of our world because we live by it, and because we cannot conceive ourselves as living otherwise.  Our conceptions of possibility, of law, of regularity, of logic, are all derived from the same source; and as we are constantly compelled to work with these conceptions, as in our increasing endeavors to better our condition and increase our provision we are constantly compelled to guide ourselves by Nature’s regulations, we accustom ourselves to look upon these regularities and conceptions as antecedent to all work, even to a Creator’s, and to judge of the origin of Nature as we judge of the origin of inventions and utilities ascribable to man.  This explains why the argument of design has enjoyed such universal popularity.  But that such popularity is no criterion of the argument’s worth, and that, indeed, it is no evidence of anything save of an unhappy weakness in man’s mental constitution, is abundantly proved by the explanation itself.”  Well, the constitution and condition of man being such that he always does infer design in Nature, what stronger presumption could there possibly be of the relevancy of the inference?  We do not say of its correctness:  that is another thing, and is not the present point.  At the last, as has well been said, the whole question resolves itself into one respecting the ultimate veracity of Nature, or of the author of Nature, if there be any.

Passing from these attempts to undermine the foundation of the doctrine—­which we judge to be unsuccessful—­we turn to the consideration of those aimed at the superstructure.  Evidences of design may be relevant, but not cogent.  They may, as Mill thought, preponderate, or the wavering balance may incline the other way.  There are two lines of argument:  one against the sufficiency, the other against the necessity, of the principle of design.  Design has been denied on the ground that it squares with only one part of the facts, and fails to explain others; it may be superseded by showing that all the facts are in the way of being explained without it.