We find ourselves asking next, then, 'What is the warrant for the connection of our A with our C?' Superficially, it may seem enough to reply that petrol is unable to flow through a partial solid, such as the dirt in the jet, with the facility of its flow through air. But there is, in fact, nothing like a self-evident connection here. We are still impelled to ask, Why? And if we find our answer now in so-called 'fundamental laws' as to the resistance of masses, etc., what we have arrived at is once more not self-evident truth but a generalisation drawn from a wide, but yet indefinitely inadequate, experience of an abstract aspect of the world. The inadequacy and the abstractness alike force upon our attention the still mysterious nature of the 'matter' which, in our unregenerate moments, we may think we 'understand'.
And similarly when we inquire into the warrant of the connection of our B with our C. How does a thin petrol supply connect with failure of combustion? We may find our ground here in a necessity that there should be maintained a certain more or less definite proportion between the molecules of petroleum and air in order to secure combustion. But why this proportion should be necessary for combustion, and so on, and so on, are questions to which, as we push back our analysis, we may find increasingly elaborate answers, but no answer which does not by its very nature set for us a fresh problem. Push back as we may, still we find ourselves faced with a union of differents in which the differents do not spring from the unity, and are therefore partially external to it. And such a complex is not one in which the intellect can find rest.
What we have found in this illustration holds, I maintain (with certain partial reservations to be explained later), for all of thought's endeavours to understand its world. The effort to gain a non-contradictory, and therefore so far a true, view of Reality dissipates itself in an infinite process. And in principle the reason is clear enough. Thought knows nothing of intrinsic connections of differents. If differences are to be connected, thought demands a 'ground' of connection. But since the ground must always be other than the differences it connects (if it were resoluble into them it would not 'connect' at all), the intellect is immediately offered a fresh element of difference which must in its turn be connected up through a deeper ground. And to this process there is no end.
Let us put it in another way. What the intellect wants in order to attain to the self-consistency which can alone manifest the real, is a complex of differences so united that the principle of their union is internal to the complex. What the intellect achieves (and the defect is incurable) is a complex of differences which refers beyond itself indefinitely for the justification of the union. The real is unity in difference, a unity which issues forth in the differences by virtue of its own nature; or - from the other side - differences which have no being save within the unity of which they are expressions. Only a complex of this kind will be self-explanatory, provoking no 'why' to which it does not itself supply the answer. But such a complex, if we have been right, it is vain to suppose attainable at any level of the process of thinking.
But, moreover, from the point we have now reached it becomes clear that we must qualify severely the language which we have so far allowed ourselves to use in alluding to the nature of the real. We have spoken of the real, above, as 'a unity issuing forth in its differences by virtue of its own nature,' and again, as a system of differences wherein perfect mutual implication reigns. And we have meant to convey thereby that the real (if it is to satisfy thought's demands) must be a unity which is not external to the differences which it combines. But the negative intention does not justify the positive description, as we now see. The latter may be used only by a licence not in the end permissible. For to speak of a whole wherein perfect mutual' implication' reigns, is to speak of differences connected by a 'ground' which is wholly internal to the differences it connects. And of a 'ground' of this sort, we have just seen, the intellect knows nothing. The positive description, accordingly, is only a name (suggested by our apprehension of the defects which must be remedied in the 'real') for our ignorance of the kind of unity which is not external to its differences. And it is in the end a misleading name, inasmuch as the use of it must tend to suggest a meaning, in terms of our ordinary conceptions of ground and implication, which can only be a distortion of reality. We must recognise that 'ground,' 'implication,' even 'necessity,' are concepts which cannot with any positive significance be applied to the union of differences in the ultimately real.
Let us gather together our thoughts and observe whither we have been led. I have argued that the path which the intellect takes and must take to avoid self-contradiction - the continuous pursuit of deeper and more adequate grounding for its connections, which is one with the pursuit of 'system' ever more comprehensive and internally harmonious - is not a path which can lead to Reality. Inherent in the very nature of the process is a reference beyond itself which raises fresh problems on the basis of temporary solutions. So far as I can see, one conclusion is inescapable. Reality in its true character must be pronounced to be disparate from each and every thought-product. And the term 'disparate' must be taken in its fullest significance. I do not mean that there is here merely a difference of degree, such as might leave it possible for us to say that certain thought-products reveal more adequately than others, although none with perfect adequacy, the character of ultimate Reality. I mean that there is a fundamental difference in kind, such as renders thought-products and Reality strictly incommensurable. This is metaphysical scepticism - though I hope to show that it is a form of scepticism not open to the objections commonly brought against this type of philosophy. Nevertheless, whether it be in the end defensible or not, it does seem to be the result to which the argument has driven us. For, according to the argument, we must have for Reality differences united in a certain way, and we actually have in thought-products differences united in a quite other way. The 'patterns' of thought-products and Reality - to use a term now much in vogue - are fundamentally diverse. And since the 'pattern' of Reality is one to which thinking gets not one whit nearer, no matter how elaborately systematic its functioning, we seem bound to say that thought by the pursuit of its own characteristic method does not make the slightest advance towards the articulation of the true nature of Reality. To make the concept of 'degrees' applicable, it is plainly necessary that there should be an intelligible continuity of principle between the lower stages and the perfect consummation. But that continuity is just what is lacking in the relation of thought-products and Reality. I find myself compelled therefore to affirm (a) that Reality owns a character which transcends thought - a character for which, since a label is convenient, we may use the term 'supra-rational'; and (b) that there is no possibility of measuring the degree in which any particular content of thought manifests the character of Reality. But since (b) clearly carries with it the rejection of the Idealist doctrine of 'Degrees of Truth and Reality,' a doctrine which no one has done more to recommend than the philosopher upon whom my argument so far has been based, it is very necessary to pause here and explain my attitude to this doctrine with some precision.