In the 1950s and 60s, when the American artist Alex Katz was a young man, Abstract Expressionism was dominant. Katz quietly rejected it, looking for something new. “The one thing I don’t want to do is things already done,” he has said. “As for particular subject matter, I don’t like narratives, basically.” Katz created and then destroyed thousands of works until he landed on his signature technique of broad brush strokes, a vibrant color palette, and crisp images. Critics embraced him as the inventor of “cool painting.” This show celebrates his 95th birthday. —E.C.