When writing a film review, I have a checklist in the back of my head. Did I mention the editing' What kind of look are the director and DoP going for - handheld cine-realism, washed-out widescreen nostalgia, garish techno-futurism' How about the sound design, the soundtrack, the miking of dialogue: is it an elocution lesson or a mumblefest' Is there something interesting to be said about the costumes, the production design, the special effects' How does the film relate to other recent post-westerns or slacker comedies'
You don't need a thorough grounding in Gilles Deleuze's post-Bergsonian film theory to write a decent film review (and thank God for that); but it helps to have a grasp of the history and techniques of the medium.
It enriches your own (and, you hope, the reader's) experience to be able to relate the long Dunkirk tracking shot in Atonement to other examples, such as the opening of Orson Welles' Touch Of Evil or the devastating slow pan and swoop at the end of Antonioni's The Passenger.
It's empowering, as a film-goer, to understand enough about 3D animation to realise the stories we're being fed by Pixar or DreamWorks have as much to do with computer animation challenges (capturing the light on fish scales, the realistic depiction of fur) as with whether fish or rats are this season's cuties.
But when it comes to acting skills, I doubt whether I have any more to contribute than the average low-frequency film-goer. Sometimes, when judging an actor's performance, as 'strong', 'authentic', 'convincing' or their opposites, the words 'good' and 'bad' would have done just as well. But as a critic, you have to use a varied vocabulary.
When it comes to evaluating acting skills, we all seem to be standing around the water cooler. Outside of studies on the Hollywood star system, acting is largely ignored by film theorists. The unquestioned ruling paradigm - for critics, members of Ampas, serious couch potatoes and actors themselves - seems to be how successfully an actor inhabits the role. But what does this mean' John Wayne 'inhabited' his best roles, and yet he was always John Wayne - even in The Searchers, where he is fascinating precisely because the world-weariness of the gruff old tracker and the world-weariness of the gruff old actor merge seamlessly.
These days, an actor such as Academy Award shoo-in Daniel Day-Lewis is praised because he disappears - astonishingly, alarmingly - into his roles. Even if you've only seen his films and read nothing about his life, it's somehow easy to separate Wayne the man, or at least Wayne the persona, from Wayne the actor. With Day-Lewis, the same exercise yields little more than a fine pair of eyebrows.
We're still in thrall to the Method, although, (i) there was never one undisputed Method, (ii) the original Method generation is dying out, and (iii) most young actors seem to have developed their own mini-Methods through trial and error.
It's difficult not to go all weak-kneed when faced with the mysterious alchemy of the process whereby one person becomes another on screen. But while we wait for performance-judging to become an exact science, I'm reluctant to be bullied by the Method hegemony into looking down on those actors who don't so much inhabit the role as bring the builders in and give it a makeover in their own image.
To ask whether Daniel Day-Lewis in There Will Be Blood is better than Johnny Depp in Sweeney Todd: The Demon Barber Of Fleet Street is a bit like getting a champion long-jumper and a champion figure-skater to do their stuff and then give just one a medal.
They're both good; but until the pendulum of taste swings back towards an appreciation of gloriously stylised performances like Depp's, we know which one is likely to lift that gold statuette.