Many men fear the loss of character or the 'wrath of Heaven，'but all men fear the scourge and the gallows.(14)He admits，however，that the religious sanction and the additional sanction of 'benevolence'have the advantage of not requiring that the offender should be found out.(15)But in any case，the 'natural'and religious sanctions are beyond the legislator's power.
His problem，therefore，is simply this：what sanctions ought he to annex to conduct，or remembering that 'ought'means simply 'conducive to happiness，'what political sanctions will increase happiness？
To answer this fully will be to give a complete system of legislation；but in order to answer it we require a whole logical and psychological apparatus.
Bentham shows this apparatus at work，but does not expound its origin in any separate treatise.Enough information，however，is given as to his method in the curious collection of the fragments connected with the Chrestomathia.
A logical method upon which he constantly insisted is that of 'bipartition，'(16)called also the 'dichotomous'or 'bifurcate'method，and exemplified by the stalled 'Porphyrian Tree.'The principle is，of course，simple.Take any genus：divide it into two classes，one of which has and the other has not a certain mark.The two classes must be mutually exclusive and together exhaustive.
Repeat the operation upon each of the classes and continue the process as long as desired.(17)At every step you thus have a complete enumeration of all the species，varieties，and so on，each of which excludes all the others.No mere logic，indeed，can secure the accuracy and still less the utility of the procedure.The differences may be in themselves ambiguous or irrelevant.If I classify plants as 'trees'and 'not trees，'the logical form is satisfied：but I have still to ask whether 'tree'conveys a determinate meaning，and whether the distinction corresponds to a difference of any importance.
A perfect classification，however，could always be stated in this form.Each species，that is，can be marked by the presence or absence of a given difference，whether we are dealing with classes of plants or actions：and Bentham aims at that consummation though he admits that centuries may be required for the construction of an accurate classification in ethical speculations.(18)He exaggerates the efficiency of his method，and overlooks the tendency of tacit assumptions to smuggle themselves into what affects to be a mere enumeration of classes.But in any case，no one could labour more industriously to get every object of his thought arranged and labelled and put into the right pigeon-hole of his mental museum.To codify(19)is to classify，and Bentham might be defined as a codifying animal.
Things thus present themselves to Bentham's mind as already prepared to fit into pigeon-holes.This is a characteristic point，and it appears in what we must call his metaphysical system.'Metaphysics，'indeed，according to him，is simply 'a sprig，'and that a small one，of the 'branch termed Logic.'(20)It is merely the explanation of certain general terms such as 'existence，''necessity，'and so forth.(21)Under this would apparently fall the explanation of 'reality'which leads to a doctrine upon which he often insists，and which is most implicitly given in the fragment called Ontology.He there distinguishes 'real'from 'fictitious entities，'a distinction which，as he tells us，(22)he first learned from d'Alembert's phrase ?tres fictifs，and which he applies in his Morals and Legislation.'Real entities，'according to him，(23)are 'individual perceptions，''impressions，'and 'ideas.'
In this，of course，he is following Hume，though he applies the Johnsonian argument to Berkeley's immaterialism.(24)A 'fictitious entity'is a name which does not 'raise up in the mind any correspondent images.'(25)Such names owe their existence to the necessities of language.Without employing such fictions，however，'the language of man could not have risen above the language of brutes'；(26)and he emphatically distinguishes them from 'unreal'or 'fabulous entities.'A 'fictitious entity'is not a 'nonentity.'(27)He includes among such entities all Aristotle's 'predicaments'except the first：'substance.'(28)Quantity，quality，relation，time，place are all 'physical fictitious entities.'This is apparently equivalent to saying that the only 'physical entities'are concrete things --sticks，stones，bodies，and so forth --the 'reality'of which he takes for granted in the ordinary common-sense meaning.It is also perfectly true that things are really related，have quantity and quality，and are in time and space.But we cannot really conceive the quality or relation apart from the concrete things so qualified and related.We are forced by language to use substantives which in their nature have only the sense of adjectives.He does not suppose that a body is not really square or round；but he thinks it a fiction to speak of squareness or roundness or space in general as something existing apart from matter and，in some sense，alongside of matter.
This doctrine，which brings us within sight of metaphysical problems beyond our immediate purpose，becomes important to his moral speculation.His special example of a 'fictitious entity'in politics is 'obligation.'(29)Obligations，rights，and similar words are 'fictitious entities.'Obligation in particular implies a metaphor.The statement that a man is 'obliged'to perform an act means simply that he will suffer pain if he does not perform it.The use of the word obligation，as a noun substantive，introduces the 'fictitious entity'which represents nothing really separable from the pain or pleasure.