Sorley delivered his Gifford Lectures in the summer terms of 1914 and 1915, giving the full double session of 20 lectures. These were published in a single volume in 1918. A second edition with minor corrections and additions was published in 1921.
Sorley's project in these lectures is, broadly speaking, a Kantian one. It takes as its starting point the philosophical task of making coherent the apparently radical division between the existent and the valuable. The traditional strategy in this regard is to investigate the world of existence – what is — and on the basis of this investigation try to establish some conclusions about the nature of value – what is good, and how things should be. This generally means beginning with science and on the strength of its findings, drawing some ethical or evaluative conclusions. Sorley adopts the reverse procedure and seeks to establish the nature of ultimate reality on the basis of an investigation of value, to establish how reality is by asking how ideally it ought to be. This strategy follows that of Lotze who held that “the true beginning of metaphysics lies in ethics” and the first lecture is devoted to an explication of this thought.
Having established, in outline, the plausibility of basing metaphysical inquiry on ethics, the next four lectures are devoted to an extensive investigation of values, their basis, their connection with existence, and the relation between values and persons. Sorley sketches four kinds of value — happiness, truth, beauty and goodness – and the important distinctions that cut across them — instrinsic/instrumental, permanent/transient, higher/lower. In Lecture III he considers and rejects some long established attempts to reduce values to mental states (such as pleasure and desire) or to social history and the development of convention. In this and the following lecture he compares scientific judgements and value judgements with a view to undermining the idea that the former are in some way more “objective” than the latter. Sorley argues that any argument which motivates scepticism about values, must apply just as much to knowledge, so that our choice is between accepting the objectivity of value judgements, or a global scepticism that throws everything in doubt.
Lecture V explores the special connection between values and persons. This connection arises from the fact that consciousness of value and its deliberate realisation are also values in themselves. Objects without consciousness, and non-deliberative animal behaviour may both have value, but can neither recognize it nor choose to realize it.
Lecture VI pursues the question of relative and absolute value. Sorley adopts and expounds the position characteristic of Absolute Idealism, that values which we often take as absolute turn out not to be, since set in a wider context they appear relative to other conditions pertaining. If by “absolute” we mean “complete” then the only possibility of absolute value lies in a unique individual entity that contains all relations within it. This conclusion applies as much to science as to morality.
This comparison with science and morality (or fact and value) continues in the following three lectures. Its full importance emerges in Lecture X, where Sorley argues that the unity of reality requires a philosophical synthesis of the deliverances of science and morality, and the existence of self and others.
Lecture XI, the first in the second series, examines the distinction between description, explanation and interpretation, and the bearing of this on finding meaning in the world. Sorley argues that explanation must be incomplete without interpretation, a key faculty in which is imagination, and Sorley considers objections to the use of imagination in the discovery of objective truth.
Theism, then, is to be understood as an interpretation of experience that reveals the meaning of existence. Lecture XII considers it directly, and the traditional arguments in its favour. Lecture XIII is devoted to just one of these — the moral argument — and offers a modified form of the argument which nevertheless relies on the arguments fundamental strategy — that the world has to have a moral order “built in” so to speak, if personal happiness, justice and moral endeavour are all to be possible.
Pluralism is then considered as a rival interpretation, and monism as its alternative. Through a detailed exploration of the requirements of purposivenes and freedom, the lectures thus return to theism, which is the subject of Lecture XVIII. The penultimate addresses the idea of God directly, and a concluding 20th lecture reviews the argument developed across the two series, and concludes in favour of a theistic interpretation of experience, acknowledging the centrality of moral values to such an interpretation and the limits that this imposes.