Return true from enumerable that calls function unless that function ever returns false
Usually positive conditions are much easier to understand than negative ones and even easier then two negatives in the same expression. You can flip it and get rid of both negations by using All instead:

return processNames.All(process =&gt; launch(process));


Now that the nagations are gone you can further shorten this by removing the lambda:

return processNames.All(launch);


This is possible because the launch method signature matches the delegate  Func&lt;string, bool&gt; required by All.