His early work includes the classic texts
Mental Acts and
Reference and Generality, the latter defending an essentially modern conception of
reference against medieval theories of supposition. His Catholic perspective was integral to his philosophy. He was perhaps the founder of
analytical Thomism (though the current of thought running through his and
Elizabeth Anscombe's work to the present day was only ostensibly so named forty years later by
John Haldane), the aim of which is to synthesise Thomistic and analytic approaches. Geach was a student and an early follower of
Ludwig Wittgenstein whilst at the
University of Cambridge. Geach defends the Thomistic position that human beings are essentially
rational animals, each one miraculously created. He dismissed
Darwinistic attempts to regard reason as inessential to humanity, as "mere sophistry, laughable, or pitiable." He repudiated any capacity for
language in animals as mere "association of manual signs with things or performances." Geach dismissed both pragmatic and epistemic conceptions of truth, commending a version of the
correspondence theory proposed by
Thomas Aquinas. He argues that there is one reality rooted in God himself, who is the ultimate truthmaker. God, according to Geach,
is truth. While they lived, he saw
W. V. Quine and
Arthur Prior as his allies, in that they held three truths: that there are no non-existent beings; that a proposition can occur in discourse without being there asserted; and that the sense of a term does not depend on the truth of the proposition in which it occurs. He is said to have invented the famous ethical example of the stuck potholer, Geach has famously argued that the notion of
absolute identity should be abandoned, to be replaced with relative identity predicates. ==Honours==