The Dadaists asked the question what is chance and where does it lie within us? Dada artists read Jung who discussed coincidence, synchronicity, causality. They saw chance as a magical way of entering the unconscious mind or the soul. They saw is as a way to restore art back to it's primevel powerful state.
Humour and laughter was also an important part of their art. Dada arose as a backlash of the times when the War had such a serious impact on society.