Optimism
It probably is not surprising that the imagery of optimism appears in a book with this title, but instead of just depicting what optimism is generically, the book seeks to explore the entire optimism/pessimism dichotomy with respect to desire and attachment. In that context, the experience commonly referred to as "optimism," might easily be a kind of regressive desire for wish-fulfillment. Optimism is essentially a word for unwarranted hope, and as the Taoist doctrine teaches, hope is essentially fear of suffering.
Desire and attachment
Berlant does not dismiss optimism wholesale. Instead, she invokes the imagery of attachment theory as a litmus test. If a person is optimistic because they are hopeful about attaining a desire, Berlant asks them to consider whether they are flourishing by that desire or whether the desire is secretly an attachment to something unhealthy, preventing them from flourishing. Berlant says that after removing one's self from Oedipal attachment, a person can employ optimism strategically to muster hope.
Cruelty and suffering
The other important word in the title besides Optimism is Cruel. Those words might seem like a strange juxtaposition, but actually, they are surprisingly related. The imagery of cruelty has similarities to the theories of Buddhism which also views the suffering of life as cruelty. The imagery of cruelty is pain and suffering, especially heinous occasions of suffering caused by an antagonist. An interesting essay could be writing on Berlant's book with regards to that aspect of the word, because by saying "Cruel" she has personified fate.
Delusion
A person can very often experience versions of reality that do not align with reality. Sometimes, these neurotic experiences of cognitive dissonance are masked by claims of optimism, which is why this imagery plays such a critical role in the book. At the end of the day, this book is a defense of truth. It is not a rejection of optimism but a demotion of optimism. Berlant says that a person who is delusional and neurotically optimistic risks experiencing one of the worst psychological hells, because the cruel joke on the sufferer is that secretly, they don't have the hope they claim to have.
