There’s a reason that curious beast the novel of ideas is rarely captured alive. It isn’t easy to animate complex notions using only the standard tools of character and plot without the whole enterprise collapsing beneath the weight of exegesis. In his new novel, “Double Blind,” Edward St. Aubyn sets himself that formidable challenge: to explore weighty subjects like biodiversity, schizophrenia and venture capitalism while probing the nature of consciousness and the limits of science. The book is also a medical melodrama, a family mystery and a meditation on . . . well, meditation. Can so many plates be kept spinning?

St. Aubyn’s protagonists are all preoccupied by questions of consciousness and being and what science can reveal about them. Francis lives off the grid rewilding a large acreage in the English countryside while pursuing a Zen-like state of mindfulness. Olivia, his new lover, is finishing a book on epigenetics. Her friend Lucy, at a crossroads in life, has impulsively hitched her star to American billionaire Hunter Sterling, whom she’s helping to buy companies that mix consumer tech with neuroscience.

When Lucy is diagnosed with a brain tumor, she and Hunter embark on an unexpected romance. This twist binds our principals together and provides St. Aubyn with an excuse to dispatch them to Hunter’s compounds in Cap d’Antibes and Big Sur, which provide the glamorous backdrops for a series of comic set pieces and encounters. Meanwhile, back in London, Olivia’s adoptive father starts to wonder if a new schizophrenic patient might be his daughter’s long-lost twin brother.

While there’s no shortage of action, St. Aubyn’s real interests are metaphysical. As his characters cogitate and self-medicate, scheme and philosophize, his subject is less the content of their thoughts than the mind contemplating itself. Which is more real: what we feel about the world or what science tells us we’re feeling? “We have an absurd situation,” observes Hunter’s friend Saul, “where the first-person narrative of experience and the third-person narrative of experiment shout insults at each other from either side of an explanatory gap, that huge, huge explanatory gap.”

This gap is a symbol of our failure to make the right — the most important — connections. Whether it’s the disconnect between philosophy and neuroscience, or limitations in our thinking about ecology, psychiatry, physics and technology, in each case, St. Aubyn seems to suggest, we’re held back from achieving the next great stride by a kind of intellectual parochialism. Science is “not a pyramid; it’s an archipelago — scattered islands of knowledge, with bridges running between some of them, but with others relatively isolated from the rest.”

If this sounds like too much for a book of 250 pages to bear, unfortunately it is. Although St. Aubyn is urbane, humorous company, he can’t stop his plot from being crowded out by the intellectual freight he tries to smuggle in. By the end of the book, so much is left unresolved that one wonders whether chapters might be missing.

Characters often seem like little more than avatars for ideas. Even the rounder ones are prone to opaque digressions and have unconversational penchants for technical vocabulary. Olivia, when asked over lunch to describe what she’s working on, launches into the “environmental stresses correlated with schizophrenia . . . marginally implicated genes . . . [and] the question of inheritability.” More like an early character sketch for a Tom Stoppard play than the glittering, if appalling, wits of St. Aubyn’s Patrick Melrose novels.

Other figures feel sketchier still. New personae are introduced in the Riviera sequence — a Scottish entrepreneur; a lascivious academic; Hunter’s too-perfect assistant, Jade — all of whom haunt a few paragraphs without becoming significant or interesting. Jade is one of a handful of Americans who feel especially flimsy — even if she’s not as flat as the libidinous New-Age Californian Hope, seemingly introduced just to provide a moral crisis for Francis.

There are flashes of St. Aubyn the Great, particularly in the one-liners. A passing reference to “a nervous albino rabbit, Alphonso, who died by nibbling voraciously through an electric cable.” A dry description of surgery as “a profession that seemed to fuse compassion and brutality, without having to reveal which was the dominant impulse, as long as both were accompanied by a high degree of precision.” His rococo metaphors, too, remain undimmed; parsing Hunter’s relationship to Lucy’s cancer, he writes, “He seemed to be undaunted, perhaps even inspired, by the insolence of her illness: a hostile take-over to outmanoeuvre, a tax for which there must be a loophole.”

But a fistful of compelling thoughts and good jokes cannot save “Double Blind” from caving in. Although St. Aubyn’s ambition is laudable, his efforts to tie together so many big ideas are made at the expense of plot, character and tone, all of which lack the emotional rigor and tight focus of his best work.

Charles Arrowsmith is based in New York and writes about books, films and music.

Double Blind

By Edward St. Aubyn

Farrar, Straus and Giroux. 256 pp. $27