I think it was a bit of both. Dadaism was a movement that attempted to destroy art, or rather, to destroy the expression of the culture that the artists hated so much for being able to cause something as heinous as World War I. One of the most famous pieces of Dadaist art illustrates this very clearly: it takes the picture of the smiling Mona Lisa and turns her into a mockery by adding a moustache and selling postcards of her as if she was an item for mass production.
The irony is that they tried to destroy "the establishment" through art, and the establishment... absolutely loved it! The Dadaist movement quickly lost traction after failing its purpose like that, until it was nothing but a couple of opportunists who tried to gain some easy profits off of a philosophy and movement that had a bright, but very short lifespan.
And then the second world war happened, which was even worse than the first, proving nobody learned anything.
You said to another poster who claimed Dadaism was about peace that it wasn't, but you're both right in a sense: Dadaism definitely was about destruction, but it was vehemently anti-war. It was about rebuilding a culture with a means that was violent, unlike (for instance) the hippies who tried to do the same through peace, love, and copious amounts of unprotected sex.
It is a philosophy, it is based on the idea that the war(and what make the war come, so what it happened before) it is bad, so you have to destry the past and re-buil the future.
Peace was certainly not what the Dadaists liked. The Dadaists believed in dynamism and action. Dada was simply a substitution for war, hell and horror. It was a serious "piece of tomfoolery".
Is Dadaism a philosophy or simply nonsense?