If, as Hilary Mantel memorably proposed, history is the way we organise our ignorance of the past, how might we tackle our ignorance of our radically changing communications present, to keep the future bright? Hope may be power, as the Guardian’s recent promotional campaign slogan asserts it is, but nurturing hope requires some shared vocabulary.

Let’s start small: what is journalism for? Besides making money and influence for a few, what purposes do media serve in societies that want to call themselves free? Even a rough consensus about that might help us assess how well those purposes are being fulfilled, and to know better how to adjust in an era of huge but clumsy social media entities and data-hungry, ethically unaccountable artificial intelligence. Four purposes of journalism, familiar even if usually expressed differently, seem to me to remain worthwhile:

It sells journalism short not to acknowledge that its finest practitioners make a distinct contribution to the culture

Help civil society to cohere Media, especially local media, serve as public forums, information collectors and disseminators and conduits through which many of the routine activities necessary to a healthy civil society happen – unnoticed until they are gone, or no longer sufficiently open. Crucially, these processes foster tolerance in the sense that they make it possible to observe the diversity, the “otherness”, around us, without requiring us to join in, or even approve. They help us rub along together – no small achievement.

Facilitate democratic processes From campaigning, debating and voting to extracting accountability and forcing into view public interest issues which we do not want to see, but which will fester to our detriment unless we face them.

Lubricate commerce Through advertising and specialist business, finance and economics reporting, since the earliest days of newspapers, journalism has served this purpose – and while it can create conflicts of interest, its byproduct is financial independence from the state, which is essential to other purposes of journalism. (How media power is held accountable is a legitimate topic, but for another day.)

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Make and mix the culture It sells journalism short not to acknowledge that its finest practitioners make a distinct contribution to the culture. But the emphasis here is on how journalism mixes what others make. Artists will create and cultural rituals will be acted out (and believed in) regardless of whether anyone observes, records, disseminates, applauds, tuts or hisses. But through reviews, listings, previews, interviews, profiles and their “nose for the new”, journalists do much to raise awareness, generate opportunity and magnify.

These verbs matter: help, facilitate, lubricate, mix. Journalism has always been self-interested, but it has done, and still does, a lot of collateral good. As communications continue to change and other players take increasingly powerful roles, we will all be affected by what they decide they are for.

• Paul Chadwick is the Guardian’s readers’ editor