EVER THE OPTIMIST, I can't help believing that 1978 has been a good year for popular music. Keeping that faith involves some studious ignorance: I try not to think about the year's best-selling discs ("Saturday Night Fever," Chuck Mangione, Wings, Boston, Billy Joel, Foreigner, "Grease," and the dismal remake of "Sgt Pepper"); or about the bland radio stations that promote them. As far as I'm concerned, that's corpo-rock: Corporate entertainment empires pouring money into research-tested sure things with conservative media outlets blindly following along. Corpo-rock is joyless, de-personalized, de-localized stuff, pre-processed background music for passive consumers. But forget those calcified top echelons, I tell myself-the important developments are brewing down below. And this year, that's where I find good cause for rejoicing.

I suspect that punk-rock-R.I.P.-is to be thanked, for the punks reminded the music community that rock 'n' roll doesn't belong to professionals, and that it can still be abrasive, primitive and high-powered. The public rejected it-a lot of punk-rock had negligible redeeming value-but an anarchic attitude has filtered into pop. Independent record companies, operated on shoestrings and loyalty, have proliferated; some are punky (like Akron's Clone Records), some good-timey (Britain's Stiff, L.A.'s Rhino), some progressive and experimental (Random Radar in Silver Spring, Md., and Ralph in San Francisco). The term "punk-rock" has given way to the vague "New Wave"; essentially, punk fertilized the whole scene. I'd bet that the average tempo of 1978 rock LPs (Bruce Springsteen excepted) is up a few notches from 1976 levels. And I'm glad.

Closer to the mainstream, 1978 has seem some superb debuts. The Cars, Boston's best band yet, ar brilliant, meticulous pop craftsmen; Jules and the Polar Bears are passionate and wild-eyed. Over in Britain, Ian Dury updates the music-hall tradition with some workingman's angst, while XTC (on Virgin Records) have released two LPs of avant-garde pop. And Nick Lowe, a behind-the-scenes matermind for Brinsley Schwartz, Elvis Costello and Rockpile, emerged in 1978 with his own "Pure Pop For Now People." These are more than "promising" debuts; they are among the year's best albums.

Yet they meet rough competition from 1978's slew of comebacks. The Rolling Stones' "Some Girls," with its shot of punky adrenalin, has been amply heralded, as have strong albums from Neil Young and Van Morrison. Lest we forget, Todd Rundgren shucked his pretensions to make a delightfully unconventional pop record; John Prine ended a three-year hiatus with witty, understated songs; Gerry Rafferty, ex-Stealer's Wheel, came out of limbo and reached the Top Ten. John McLaughlin, whose original Mahavishnu Orchestra set off shock waves in jazz and rock, returned from dabblings in Indian music and acoustic guitar to make the fiery "Johnny McLaughlin, Electric Guitarist." Betty Wright, a dynamic R&B singer, finally cashed in with a live album. Meanwhile, the zany NRBQ took a major-label offer, put out "At Yankee Stadium"-maybe their best LP-and were promptly dropped. And Captain Beefheart, who prefigured the New Waves seven years early, is back in the spotlight; the new "Shiny Beast" ranks Report, Bob Seger, and Hall & Oates delivered on cue, while comparative youngsters, Elvis Costello, Cheap Trick, Blondie, Tom Petty and Patti Smith, gained substantial audiences.

There must be something in the air. Rockers have finally gotten enough gumption to stave off disco. Admittedly, it does keep studio musicians gainfully employed, and there is some clever disco around-various Gamble & Huff, Giorgio Moroder and Alex R. Constandinos productions, A Taste Of Honey, and the nutty Parliament/Funkadelic, who aren't entirely disco-but the machine-tooled anonymity of most of it gives me the creeps.

From machines and repetition, among other things, the amazing Brian Eno has drawn inspiration for two important albums: his own "Before and After Science" and the Talking Heads' "More Songs About Buildings and Food." which he produced. (A third Eno production, Devo, suffers from weak material.) Eno's own LP is filled with playful, free-associative pop songs laced with his instrumental "strategies"; for "More Songs" he bolsters the Talking Heads' dire, funny, psychotic visions of modern America with sundry mechanisms that neatly complement the Heads' own robotic leanings. By no means are these disco records, but they are aware of disco's implications.

For jazzmen, disco is still a threat, and Chuck Mangione-style MOR must be encroaching from the other direction. Still, there seem to be other choices than playing dumb or starving. Jazzmen from Dexter Gordon to Charles Mingus to Cecil Taylor enjoy major-label distribution, while independent labels like Inner City, Muse, Improvising Artists, JCOA, Choice, Xanadu and India Navigation also scrape by. This year, Milestone Records sponsored a Sonny Rollins-McCoy Tyner-Ron Carter tour that ought to result in an excellent album; Air, a trio whose empathy never fails to enthrall me, put out two discs for Artista Novus; Keith Jarrett released a 10-disc solo set I still haven't digested, and reissue programs by Blue Note, Prestige, Impulse and Savoy continued apace.

There have been some disappointments this year, it's true: the deaths of Lynyrd Skynyrd members and the Who's Keith Moon, the breakup of Television, some and dud albums. Still I can't help thinking that an irreverent spirits is abroad, sowing experimentation and silliness. Just the other day I opened my mail to find a record by the Temple City Kazoo Orchestra (Rhino): a dozen guys dressed in tuxedos, performing "Miss you," the Bee Gees' "Stayin' Alive," "2001 Sprach Kazoothra" and Led Zeppelin's "Whole Lotta Love"-on kazoos. What goes on here, anyway?