I learned about this from Leiter's Blog. Brian O'Shaugnessy has died.
I did not know O'Shaugnessy. But, while I rarely found myself in agreement with the positions he defended, I can say that I learned a lot from his writings and always found his essays stimulating.
Those familiar with his work know that O'Shaugnessy's contributions to the philosophy of action and philosophy of mind were often difficult, sometimes frustrating, but always challenging and innovative. For those unfamiliar with his work, O'Shaugnessy was one of the main figures in the philosophy of action who attempted to revive volitionism and helped make it one of the main contenders for a theory of action Recently, his work focused on self-awareness. But his work on the topic focused on self-awareness of agency. For an introduction to O'Shaugnessy, the best place to start is his essay, "Trying (as the Mental 'Pineal Gland')," Journal of Philosophy 70 (1973), pp. 365-386 (it can also be found, with an appendix, in Al Mele's edited collection, The Philosophy of Action (OUP, 1997)). If you are brave and have a lot of time, read O'Shaugnessy's The Will, 2nd ed., 2 vols.(CUP 2008). A website for a recent conference held in his honor, with audio files of talks by a number of prominent philosophers of mind and action (e.g., Christopher Peacocke, Paul Snowden, Lucy O'Brien, Tyler Burge), can be found here.