Schopenhauer needs no introduction. Historically, perhaps few philosophers have been at once so much adulated and reviled, depending on the spirit of the times.
His ethics, philosophies of nature, art and religion and his general system of "idealism" (if we can call it that) have certainly received less careful and charitable study compared to Kant or Hegel. A great merit of Shapshay's book is that, beyond merely stating that such a treatment (which often amounted to caricature) was profoundly underserved, she sets about to diagnose the causes for such historical neglect and disparagement as well as pointing out some key aspects of Schopenhauer's work that render it of great contemporary interest. There are moreover several questions and arguments raised in the book that, even if we must consider the conclusions mistaken, are nevertheless of extraordinary interest to the philosophy of religion and the analysis of spiritual practices. These questions merit perhaps a whole second book or sequel.
Let us start with Shapshay's deconstruction of the caricature of Schopenhauer (which is also simultaneously a "reconstruction" of the true Schopenhauer). Everyone is probably aware of it: the philosopher of doom and gloom, of nihilism and worthlessness, of despair, fatalism, resignation, hopelessness, of the meaninglessness and inherent misery of life. Shapshay appeals to Dürer's famous "Knight of Despair" to illustrate this caricature.
Shapshay, based on the Schopenhauerian corpus itself, demolishes this caricature and replaces it with a "Knight of Hope" by proving:
i) Schopenhauer never espoused strict determinism but rather remained close to Kant's theory of the "intelligible nature" in so far as he allowed for the co-existence of transcendental freedom and empirical causal determinism.
ii) Schopenhauer's ethics involved, as did Kant's, a form of moral realism and a theory of the intrinsic value of sentient beings (both human beings and animals)
iii) Schopenhauer's later works inclined to the view that there are some grounds for hope that moral action and social reform may improve the lot of sentient beings and
the world at large. This is incompatible with the espousing of complete resignation and passivity.
iv) Schopenhauer's ethics, while founded on the direct feeling of compassion, can yet allow reason to play an important role, thus minimizing his allegedly drastic break with Kant. Even if reason is metaphysically the "world that has been pulled down over our eyes to blind us from the truth", it still has a vital practical role to play so long as we engage in action in the world.
v) Schopenhauer's most complete exposition of his ethics is found in his essay "On the Foundation of Morals". Here the treatment is purely empirical and analytical (some arguments recall ordinary language philosophy) and does not depend on the acceptance of his system of idealism although the concluding section points to the inherent underlying metaphysical epistemic aspect of morality. This is an important aspect of Schopenhauer which links him strongly to ancient Buddhist and Vedantic doctrines: the idea that morality is based on or expresses direct metaphysical knowledge regarding the underlying metaphysical unity of sentient beings.
From Shapshay's analysis Schopenhauer emerges as a systematic and coherent moral philosopher of considerable contemporary interest (including socially and politically) as well methodologically valuable for interpreting ancient eastern philosophy and spiritual practices. The highlights of his ethics are the fundamental role of compassion and the attribution of essential moral worth not only to human beings but to all sentient beings.
However we would also like to offer some criticism regarding several aspects of the book.
1) The arguments against the intrinsic moral value of plants seem very weak and somewhat surprising. They are at odds with for instance the large body of scientific evidence regarding the complex social behavior and inter-communication of trees in a forest and the possibility of seeing whole ecosystems as a single living beings. It also goes against deep moral intuition regarding the wrongfulness of felling trees and the destruction of plant life in general - something also attested in ancient spiritual traditions such as Buddhism and Jainism.
2) Shapshay proposes that Schopenhauer's initial Goethean philosophy of nature was to some extent abandoned and modified in his later work for a framework which no longer involves a non-reduction explanation via substantial forms (articulated clearly WWI1 for instance) and which was closer to Darwinism. Whether this be or not the case, contrary to Shapshay I would view such development as diminishing rather than increasing the philosophical and scientific merit of Schopenhauer's philosophy of nature.
3) Shapshay does not develop or give due weight to a foundational aspect of Schopenhauer's philosophy: his Kantian Platonism. Schopenhauer offers a detailed theory on how it is possible to attain "knowledge and freedom", to attain super-individual states of being and super-rational forms of cognition - attaining the intelligible realm and exit from the Platonic Cavern. While, as we have seen, the metaphysical cognition implicit in compassionate moral action is already a form of super-individual and super-rational knowledge, Schopenhauer develops his theory of "knowledge and freedom" specifically in his philosophy of art and his (in)famous theory of the "negation of the will to live" - the path of renunciation and sainthood. Shapshay's error is not only to downplay Schopenhauer's Platonism (just as she did in regards to his philosophy of nature) but to attribute the theory of the "negation of the will" and renunciation to the Knight of Despair, to the pessimistic side of Schopenhauer, to a resignation and asceticism incompatible with the positive and hopeful moral theory detailed in her book. The adoption of this position may be partially due to Schopenhauer himself having delineated the path of renunciation and asceticism (in WWI1) in terms of specifically Christian mysticism (Saint Paul, Augustine, Luther, De Kempis, Madame Guyon, but also Eckhart and Angelus Silesius) without a fuller understanding of the Upanishadic and Buddhist paths (which should be contrasted to other more morbid and extreme Shramanic traditions), even if he claimed deep affinity with them. We contend (it is a project of ours to develop this in detail) that an authentic understanding of Upanishadic and original Buddhist philosophy and spiritual practices (which are permeated with hope, joy, bliss and freedom) provide a solid framework for arguing for the compatibility and mutual complementarity between the hopeful compassionate moral realism expounded by Shapshay and the practice of attaining super-individual and super-rational states of "knowledge and freedom".