Indeed, the trio joined sometime musical partner Neil Young last year for the Freedom of Speech tour, with no less an aim than the impeachment of US President George W. Bush.
"It was an intense, incredible tour," says British-born Nash, 64, from Los Angeles, where he spends most of his time when not at home in Hawaii.
"The present administration of George Bush has done horrible things, not only to American foreign policy, but to domestic policy, to spying on Americans and curtailing our civil rights.
"It has been a disaster. But I think people have felt a sea change coming. Two or three years ago it was a case of if you don't agree with the President then you are un-American. I think that has all changed."
Given the backlash against Bush at the mid-term elections, in November, Nash feels vindicated by his stance. And having played to half a million people on the tour, he thinks they could have even had a direct effect in turning some voters to the Democratic cause.
The softly-spoken Nash still bears traces of the accent of his childhood in the north of England and he liberally peppers the conversation with hippie-style phrases. But all that belies his steely resolve to effect change at the highest level and his sharp mind for business and cutting-edge technology.
Not only is Nash a skilled and astute songwriter, he is a respected photographer and a trailblazer in the fields of digital printing and surround sound, too.
Nash will visit Australia next month for a series of outdoor shows with Stills and Crosby.
The three have been making music together for almost 40 years, since famously meeting in Joni Mitchell's living room. Nash added his vocal harmony to a song Stills and Crosby were working on and the three were floored by how perfectly their voices blended.
In 1969 the self-titled debut, Crosby, Stills and Nash, included enduring hits such as Helplessly Hoping, Marrakech Express, Suite: Judy Blue Eyes and Guinnevere, and, later that year, the trio was joined by Young to play at the generation-defining Woodstock Festival.
Ever since, the four have played and recorded together off and on - in addition to their solo careers - in what has been an often volatile partnership.
The four have at different times gone for years without talking to each other and it is Nash who has been described as the glue holding them together.
"We have done every single thing from fighting to loving," says Nash. "It's four brothers who sometimes don't agree. But through maturity and growing a little older, we have realised we can work it out and the relationship for the last six years has been phenomenal."
Nash has remained particularly close to Crosby and stuck by him through his many years of drug and alcohol abuse, and brushes with the law. The pair released a studio album in 2004 and Nash is producing a box set for his old mate.
After the success of the tour on the back of Young's Living With War album, the quartet hopes to rope in Willie Nelson to record a new song, called In Your Name, which Nash describes as a "look at how we kill in the name of God and how unreligious that really is".
Nash credits their popular longevity to the spark they still have when performing together, an undiminished desire to create and a willingness to speak out for what they believe in.
"There always seems to be something to protest against," he says. "Unfortunately, some of the things that we spoke about in 1969 against the Vietnam War, when I wrote Military Madness, which was about my father, are still incredibly relevant today. That is both thrilling and depressing.
"I can afford not to do any of this, but I can't do without it. It makes us feel good, it makes our audience feel good and we are happy to do it."
Nash says the spirit of social activism, which inspired him and others of his generation, is still alive, and names Beck as the modern musician he most admires.
"I admire people like the Beastie Boys, particularly their campaign to do something about the terrible situation in Tibet, and Bruce Springsteen with his Pete Seeger album.
"There are a lot of people doing good work - Peter Gabriel giving people cameras to document human rights abuses."
As a long-time opponent of nuclear power (he founded Musicians for Safe Energy in 1979) and an environmentalist, Nash is prepared to put his money where his mouth is. He ensures all the vehicles he uses on tour run on bio-diesel fuel and invests in wind farms and tree planting in an effort to make his shows carbon neutral.
The CSN shows in Australia will not be as politically pointed as last year's US tour ("far be it for us to tell Australians what to do"), but expect a message or two among the sublime harmonies and parade of hits.
"I will certainly encourage the journey towards alternative energies that doesn't make us dependent on foreign oil," Nash says.
"That's what people are starting to find out, that the reason we are fighting a war in Iraq is basically because of the oil. It's not a situation where we wanted to bring democracy to Iraq. I mean, who the hell are we to tell them how to run their country?"
