Bentham's method of laying out his subject is admirable as a preservative against one kind of narrow and partial views. He begins by placing before himself the whole of the field of inquiry to which the particular question belongs, and divides down till he arrives at the thing he is in search of; and thus by successively rejecting all which is not the thing, he gradually works out a definition of what it is. This, which he calls the exhaustive method, is as old as philosophy itself. Plato owes everything to it, and does everything by it; and the use made of it by that great man in his Dialogues, Bacon, in one of those pregnant logical hints scattered through his writings, and so much neglected by most of his pretended followers, pronounces to be the nearest approach to a true inductive method in the ancient philosophy. Bentham was probably not aware that Plato had anticipated him in the process to which he too declared that he owed everything. By the practice of it, his speculations are rendered eminently systematic and consistent; no question, with him, is ever an insulated one; he sees every subject in connexion with all the other subjects with which in his view it is related, and from which it requires to be distinguished; and as all that he knows, in the least degree allied to the subject, has been marshalled in an orderly manner before him, he does not, like people who use a looser method, forget and overlook a thing on one occasion to remember it on another. Hence there is probably no philosopher of so wide a range, in whom there are so few inconsistencies. If any of the truths which he did not see, had come to be seen by him, he would have remembered it everywhere and at all times, and would have adjusted his whole system to it.
And this is another admirable quality which he has impressed upon the best of the minds trained in his habits of thought: when those minds open to admit new truths, they digest them as fast as they receive them.
But this system, excellent for keeping before the mind of the thinker all that he knows, does not make him know enough; it does not make a knowledge of some of the properties of a thing suffice for the whole of it, nor render a rooted habit of surveying a complex object (though ever so carefully) in only one of its aspects, tantamount to the power of contemplating it in all. To give this last power, other qualities are required: whether Bentham possessed those other qualities we now have to see.
Bentham's mind, as we have already said, was eminently synthetical. He begins all his inquiries by supposing nothing to he known on the subject, and reconstructs all philosophy ab initio, without reference to the opinions of his predecessors.
But to build either a philosophy or anything else, there must be materials. For the philosophy of matter, the materials are the properties of matter; for moral and political philosophy, the properties of man, and of man's position in the world. The knowledge which any inquirer possesses of these properties, constitutes a limit beyond which, as a moralist or a political philosopher, whatever be his powers of mind, he cannot reach.
Nobody's synthesis can be more complete than his analysis. If in his survey of human nature and life he has left any element out, then, wheresoever that element exerts any influence, his conclusions will fail, more or less, in their application. If he has left out many elements, and those very important, his labours may be highly valuable; he may have largely contributed to that body of partial truths which, when completed and corrected by one another, constitute practical truth; but the applicability of his system to practice in its own proper shape will be of an exceedingly limited range.
Human nature and human life are wide subjects, and whoever would embark in an enterprise requiring a thorough knowledge of them, has need both of large stores of his own, and of all aids and appliances from elsewhere. His qualifications for success will be proportional to two things: the degree in which his own nature and circumstances furnish them with a correct and complete picture of man's nature and circumstances; and his capacity of deriving light from other minds.
Bentham failed in deriving light from other minds. His writings contain few traces of the accurate knowledge of any schools of thinking but his own; and many proofs of his entire conviction that they could teach him nothing worth knowing. For some of the most illustrious of previous thinkers, his contempt was unmeasured. In almost the only passage of the 'Deontology' which, from its style, and from its having before appeared in print, may be known to be Bentham's, Socrates, and Plato are spoken of in terms distressing to his great admirers; and the incapacity to appreciate such men, is a fact perfectly in unison with the general habits of Bentham's mind. He had a phrase, expressive of the view he took of all moral speculations to which his method had not been applied, or (which he considered as the same thing) not founded on a recognition of utility as the moral standard; this phrase was 'vague generalities'. Whatever presented itself to him in such a shape, he dismissed as unworthy of notice, or dwelt upon only to denounce as absurd. He did not heed, or rather the nature of his mind prevented it from occurring to him, that these generalities contained the whole unanalysed experience of the human race.
