This book seeks to assess the influence of Kierkegaard on Wittgenstein, an influence that perhaps would not be obvious to the casual reader of philosophy, were Wittgenstein not explicit in his own writings about his high regard for Kierkegaard.
The spheres mentioned in the title correspond to the three spheres that Kierkegaard describes in his works, which are: the aesthetic, the ethical, and the religious. These have ascending importance for Kierkegaard in that order. The author explains how the thoughts of Wittgenstein can be shown to fit within this system of three spheres; which might be better understood if the meaning of the spheres can be better explained: each sphere has it's own internally consistent system, but to ascend to a higher sphere, one must think of things within a different framework. The confusion that this can lead to is made obvious by the meaningless that Wittgenstein declares that metaphysical statements often have when analysed from a logical or grammatical viewpoint.
An illustation of thinking within the first sphere is the first volume of Kierkegaard's Either/Or, of the second and third sphere - the second volume of the same book, and also Kierkegaard's Fear and Trembling, whereas Wittgenstein's Tractatus is largely logical, and not in any given sphere, except the last few pages of the book which deal very much in the ethical and religious spheres.
But to think about what the two have in common, the above is to very much miss the point. Both seek to contribute to philosophy not by saying what it is possible to do, but by describing what it is not possible to do. They both see their task as a pruning of philosophy. They both have written works (Wittgenstein's Tractatus, and Kierkegaard's Concluding Unscientific Postscript) which refute their contentents in their closing passages, and not just their contents, but the whole philosophical framework under which the contents are written. This they do to demolish systems of philosophy that they see as invalid, in order to focus the efforts of philosophers on the parts of philosophy that can rightly be considered; this is not entirely the same as what Kurt Goedel did with his incompleteness theorum, it is in a sense even more severe than than. In this way they denigrate what Kierkegaard calls the "premise author", he who wants to instruct us with a text book of premises, or facts, that we must learn and understand, and instead seek to change the way that philsophers think about what it is appropriate to consider. In this way they both intimate to the reader that what is most important in philosophy is what is beyond language and logic, what is the ineffable.
More would be gained from reading this book if the reader were wholly familiar with the works of both Kierkegaard and Wittgenstein, but having only read some of each author's works, I felt that I could not understand all of the finer points. What I did think, however, was that the intention of both Wittgenstein and Kierkegaard, in the writing of the works I had read, was clarified, and shown to fit into a larger and more subtle internally consistent system. This book would not be recommended to the casual reader of philosophy, but to someone who has an interest in both Kierkegaard and Wittgenstein and who seeks further discussion and analysis of the thoughts of these two intriguing individuals. ( )