If you are unfamiliar with Thomas Ligotti's fiction and this non-fiction book and want to get a sense of where he's at and what The Conspiracy Against the Human Race is about, I recommend that you check out horror writer (and college teacher and musician) Matt Cardin's excellent interview of Ligotti, which can easily be found on the web (it's at Matt's "the teeming brain" WordPress blog). Although The Conspiracy Against the Human Race has a foreword by philosopher Ray Brassier (author of the highly recommended though difficult Nihil Unbound: Enlightenment and Extinction) and a back cover endorsement by philosopher David Benatar, Ligotti explains in the interview that CATHR "is by no means a philosophical work," but is instead "a synthesis of ideas I've formed over my life and of other people's ideas that rhyme with mine." He also refers to CATHR as his "Unabomber-style essay." Despite that disclaimer, I would say that CATHR qualifies as an expression of philosophical pessimism and philosophical nihilism (and antinatalism, defined at Wikipedia as "the philosophical position that asserts a negative value judgment towards birth"), and that the aforementioned endorsements from professional philosophers make perfect sense.
While Ligotti only makes a brief, indirect reference to the work of Ernest Becker in CATHR (Becker's book Denial of Death was awarded a Pulitzer Prize for non-fiction two months after Becker's death from cancer at age 49 in 1974), the general spirit is similar. To quote from Becker's introduction to his book Escape From Evil, "At its most elemental level the human organism, like crawling life, has a mouth, digestive tract, and anus, a skin to keep it intact, and appendages with which to acquire food. Existence, for all organismic life, is a constant struggle to feed--a struggle to incorporate whatever other organisms they can fit into their mouths and press down their gullets without choking. Seen in these stark terms, life on this planet is a gory spectacle, a science-fiction nightmare in which digestive tracts fitted with teeth at one end are tearing away at whatever flesh they can reach, and at the other end are piling up the fuming waste excrement as they move along in search of more flesh." But while Becker envisions a light at the end of the tunnel, Ligotti envisions only endless darkness.
Readers who may be disinclined to share Ligotti's bleak worldview or who find that Ligotti's ideas as expressed in CATHR do not "rhyme" with theirs, may nevertheless appreciate and benefit from reading CATHR. In his followup to his NY Times "Opinionater" essay "Should This Be the Last Generation?," ethicist/philosopher Peter Singer cites Benatar's antinatalist book Better Never to Have Been and says that although he does not agree with Benatar's conclusions (that it would be for the best if the human race became voluntarily extinct) and does not think Benatar is "right," "I hope those with a serious interest in these issues will read Benatar's book. They may end up disagreeing with him, but I doubt that they will think his position absurd." (Singer's followup essay from which I quote is titled "'Last Generation?': A Response.") While I can't say at this point if or to what degree I agree or disagree with the ultimate conclusion implicit in Ligotti's CATHR or if I think Ligotti is "right" that life is "MALIGNANTLY USELESS," I hope that anyone with a serious interest in questions about the meaning of life, the value of existence, the tragic, the nature and degree of human self-deception and denial of what Ligotti calls "the nightmare of being," philosophical pessimism, philosophical nihilism, and philosophical antinatalism, and the function of horror entertainment will read CATHR. And I think that even those who end up disagreeing with him or who find themselves unsympathetic to what he says, or who simply find that what Ligotti says doesn't "rhyme" with their sensibilities, will find themselves intellectually, emotionally, and psychologically challenged, and as Singer says in regards to Benatar, "I doubt that they will think his position absurd."
As someone who has had an interest in Buddhist philosophy and psychology (which I distinguish from Buddhist religious trappings and rituals) since the late sixties, I was pleased to see Ligotti's references to Buddhism in CATHR, and I would say that there is a sense in which CATHR is a sobering exploration of the "First Noble Truth" of Buddhism, which is that "Life is suffering."
CATHR has 18 pages of endnotes, but no bibliography or index, and I think future editions would benefit from the addition of both.