They can change the way people perceive ideas, and even how we perceive one another.
The way we name ideas and policies can make all the difference between popular approval and outright defeat.
The UK Government's welfare changes for example, can be described by supporters as necessary reforms to simplify the system, or by opponents as an assault on the poorest people in society, even the death of the welfare state.
Most people won't be surprised that I tend to take the latter view.
Very soon, hundreds of thousands of households will be hit by what the Tories and their LibDem allies describe as "under-occupancy rules."
Everyone else in the country has adopted a punchier name; the bedroom tax.
Slashing up to 25% from housing benefit for people in council or housing association homes, on the basis that they have one or more "extra" bedrooms will mean huge numbers of the UK's poorest people losing out, some by nearly £100 a month.
When this policy begins in April we're likely to see increased poverty, debt, evictions and homelessness.
This isn't an accident; it's the deliberate aim of the policy.
It's to do with the words being used.
Debate about welfare has become dominated by words such as "scroungers" and "skivers", to contrast with "strivers" and that old favourite, "hard-working families."
This language is designed to undermine the compassion people feel for one another, it sets "us" against "them."
It's the opposite of the purpose of a welfare state where everyone contributes to social protection, and everyone benefits. Where we really are all in it together.
This government wouldn't be finding it politically possible to pursue this agenda if they hadn't used such divisive language to change the way people see one another.
Once upon a time, not so very long ago, a battered and indebted country fought for and won a welfare state to be proud of.
It's now being dismantled in front of our eyes, and this generation must summon up the same determination and win that same battle all over again.