James E. Mahon examines the role played by Judith Jarvis Thomson's essay on abortion, published in Philosophy & Public Affairs, in the subsequent development of practical ethics as a field of inquiry. Mahon argues that the journal put the topic of abortion on the philosophical map, and Thomson's article did more than any other, before it or since, to energize philosophical debate about abortion. Mahon also analyses the contrasting arguments of Thompson and Joseph Mahon on abortion, before concluding with an examination of the distinction between the claims that abortion is "indecent" and that it is "impermissible".