[164] The later Sceptics ¹ hand down Five Modes leading to suspension, namely these: the first based on discrepancy, the second on regress ad infinitum, the third on relativity, the fourth on hypothesis, the fifth on circular reasoning.

[165] That based on discrepancy leads us to find that with regard to the object presented there has arisen both amongst ordinary people and amongst the philosophers an interminable conflict because of which we are unable either to choose a thing or reject it, and so fall back on suspension.

[166] The Mode based upon regress ad infinitum is that whereby we assert that the thing adduced as a proof of the matter proposed needs a further proof, and this again another, and so on ad infinitum, so that the consequence is suspension, as we possess no starting-point for our argument.

[167] The Mode based upon relativity, as we have already said, ² is that whereby the object has such or such an appearance in relation to the subject judging and to the concomitant percepts, but as to its real nature we suspend judgement.

[168] We have the Mode based on hypothesis when the Dogmatists, being forced to recede ad infinitum, take as their starting-point something which they do not establish by argument but claim to assume as granted simply and without demonstration.

[169] The Mode of circular reasoning is the form used when the proof itself which ought to establish the matter of inquiry requires confirmation derived from that matter; in this case, being unable to assume either in order to establish the other, we suspend judgement about both.

That every matter of inquiry admits of being brought under these Modes we shall show briefly in this way.

[170] The matter proposed is either a sense-object or a thought-object, but whichever it is, it is an object of controversy; for some say that only sensibles are true, others only intelligibles, others that some sensible and some intelligible objects are true. ³ Will they then assert that the controversy can or cannot be decided? If they say it cannot, we have it granted that we must suspend judgement; for concerning matters of dispute which admit of no decision it is impossible to make an assertion. But if they say that it can be decided, we ask by what is it to be decided.

[171] For example, in the case of the sense- object (for we shall base our argument on it first), is it to be decided by a sense-object or a thought-object? For if they say by a sense-object, since we are inquiring about sensibles that object itself also will require another to confirm it; and if that too is to be a sense-object, it likewise will require another for its confirmation, and so on ad infinitum.

[172] And if the sense-object shall have to be decided by a thought-object, then, since thought-objects also are controverted, this being an object of thought will need examination and confirmation. Whence then will it gain confirmation? If from an intelligible object, it will suffer a similar regress ad infinitum; and if from a sensible object, since an intelligible was adduced to establish the sensible and a sensible to establish the intelligible, the Mode of circular reasoning ⁴ is brought in.

[173] If, however, our disputant, by way of escape from this conclusion, should claim to assume as granted and without demonstration some postulate for the demonstration of the next steps of his argument, then the Mode of hypothesis will be brought in, which allows no escape. ⁵ For if the author of the hypothesis is worthy of credence, we shall be no less worthy of credence every time that we make the opposite hypothesis. Moreover, if the author of the hypothesis assumes what is true he causes it to be suspected by assuming it by hypothesis rather than after proof; while if it is false, the foundation of his argument will be rotten.

[174] Further, if hypothesis conduces at all to proof, let the subject of inquiry itself be assumed and not some other thing which is merely a means to establish the actual subject of the argument ; but if it is absurd to assume the subject of inquiry, it will also be absurd to assume that upon which it depends. ⁶

[175] It is also plain that all sensibles are relative; for they are relative to those who have the sensations. Therefore it is apparent that whatever sensible object is presented can easily be referred to one of the Five Modes. And concerning the intelligible object we argue similarly. For if it should be said that it is a matter of unsettled controversy, the necessity of our suspending judgement will be granted.

[176] And if, on the other hand, the controversy admits of decision, then if the decision rests on an intelligible object we shall be driven to the regress ad infinitum, and to circular reasoning if it rests on a sensible; for since the sensible again is controverted and cannot be decided by means of itself because of the regress ad infinitum, it will require the intelligible object, just as also the intelligible will require the sensible.

[177] For these reasons, again, he who assumes anything by hypothesis will be acting illogically. Moreover, objects of thought, or intelligibles, are relative; for they are so named on account of their relation to the person thinking, and if they had really possessed the nature they are said to possess, there would have been no controversy about them. Thus the intelligible also is referred to the Five Modes, so that in all cases we are compelled to suspend judgement concerning the object presented.

Such then are the Five Modes handed down amongst the later Sceptics; but they propound these not by way of superseding the Ten Modes but in order to expose the rashness of the Dogmatists with more variety and completeness by means of the Five in conjunction with the Ten.