Peter Geach - obituary - Telegraph In the philosophy of religion, Geach contributed to a better understanding of existence, or the act of being. An important distinction he made was between the ideas "there is a God" and "God is, or lives." In the latter sense God is identical with his being. Geach's thinking on this question is touched on in God and the Soul (1969) and Providence and Evil (1977). In ethics, Elizabeth Anscombe made a celebrated rejection of a kind of utilitarianism that she named consequentialism. Since many modern ethicists rejected a divine system of laws, she proposed a system of morals based on virtues. Some of Geach's own ideas on virtue ethics were given in The Virtues (1977), based on his Stanton Lectures of 1973. There were some surprises. "We ought, I think, to judge about Cannabis indica much as we judge about alcohol," he said in one lecture. Cannabis indica appears to be less mentally disturbing than alcohol, less productive of damaging accidents like car crashes, and very much less addictive. In his paper "Good and Evil," published in the journal Analysis in 1956, Geach had shown how the meaning of the word "good" depended on the substantive that it qualified: a good apple being very different from a good knife. It was an influential insight, taken up by Philippa Foot among others. Unlike the dense, unsignposted prose of Anscombe, Geach's style was a pleasure to read. In their joint volume Three Philosophers (1961), Anscombe contributed a penetrating analysis of Aristotle that was a hard slog for readers, and Geach two sections: one on Aquinas that was both clear and full of new insights, and one on Frege in which the chief obstacle for the general reader was the mathematical language of the philosopher's logic. It was largely through Geach, whose lectures on Frege were encouraged by Wittgenstein in 1950, that the importance of Frege's philosophy was realised in Britain. Geach's style was described by the philosopher Jenny Teichman as "deliberately outrageous." Having sharpened his wits on philosophers as formidable as Hume or Russell, he could seem fiercer than an Old Testament prophet and did not fear to give hard knocks to living philosophers. Yet some of Geach's phrases became the common coin of philosophers, such as a "Cambridge change." This is the notion suggested by Bertrand Russell's thought: that Socrates changes if something can be predicated of him that could not be predicated before. Thus if Socrates's son grows bigger than him, it becomes true to say Socrates is shorter than his son, and so Socrates would have changed. But this is not a real change, only a "Cambridge change." Geach's interest in the thought of both Wittgenstein and Aquinas made him an honorary founder of the philosophical school that called itself "analytical Thomism." But while Geach was a philosopher and Catholic, his philosophy went wherever the force of logic demanded, rather than being tailored to a religious conclusion. "To me it appears blasphemous to say God is 'above" logic," he wrote. Logic is not partisan, and knows nothing but to strike straight; but the sword is invincible, bearing the Maker's name. Peter Thomas Geach was born in London on March 29 1916, the son of George Hender Geach, the principal of a training college in India, and Eleonora Sgonina, the daughter of Polish emigrants. He went to live with his Polish grandparents in Cardiff, his mother having separated from his father when he was four. He was sent to Llandaff Cathedral School, and then Clifton College, before going up to Balliol College, Oxford, gaining a first in Greats in 1938. He was to spend the years 1945 to 1951 in philosophical research in Cambridge, and the next 15 years at Birmingham University, before being appointed Professor of Logic at Leeds in 1966, retiring in 1981. From 1971 to 1974 he gave the Stanton Lectures in the philosophy of religion at Cambridge. The year 1938 had seen him received into the Catholic Church. It was also the year he met Elizabeth Anscombe, who had independently become a Catholic. Once she had taken her finals, they married, on Boxing Day 1941, and decided that she should keep her maiden name. With her, Geach had seven children, four of them girls. Most of the apocryphal stories in academe about the children had some basis in reality: how they would at a tender age cook alarming meals for their parents and guests; how they would appear clothed strangely, or not at all, in the middle of some seminar; how one child, on being told that if her teddy was not in the drawing room it must be in her bedroom, retorted: "But that doesn't follow." The "Geachcombes," though each sometimes holding a post elsewhere, shuttled between Oxford and Cambridge, where Geach got to know Wittgenstein. Wittgenstein lodged with them (in Oxford) towards the end of his life. Together, Geach and Anscombe translated Descartes's Philosophical Writings (1954). In the Fifties, while Elizabeth Anscombe was doing the work that became her dense, short and influential book Intention (1957), Geach also turned his attention to the philosophy of mind in Mental Acts (1957). Peter Geach listed his recreations as "reading stories of detection, mystery and horror; collecting and annotating old bad logic texts." Elizabeth Anscombe died in 2001; Peter Geach is survived by his children. Peter Geach, born March 29 1916, died December 21 2013