Turing, Lovelace, and Babbage

The principles on which all modern computing machines are based were enunciated more than a hundred years ago by a Cambridge mathematician named Charles Babbage.’ So declared Vivian Bowden—in charge of sales of the Ferranti Mark I computer— in 1953.1 This chapter is about historical origins. It identifies core ideas in Turing’s work on computing, embodied in the realisation of the modern computer. These ideas are traced back to their emergence in the 19th century where they are explicit in the work of Babbage and Ada Lovelace. Mechanical process, algorithms, computation as systematic method, and the relationship between halting and solvability are part of an unexpected congruence between the pre-history of electronic computing and the modern age. The chapter concludes with a consideration of whether Turing was aware of these origins and, if so, the extent—if any—to which he may have been influenced by them. Computing is widely seen as a gift of the modern age. The huge growth in computing coincided with, and was fuelled by, developments in electronics, a phenomenon decidedly of our own times. Alan Turing’s earliest work on automatic computation coincided with the dawn of the electronic age, the late 1930s, and his name is an inseparable part of the narrative of the pioneering era of automatic computing that unfolded. Identifying computing with the electronic age has had the effect of eradicating pre-history. It is as though the modern era with its rampant achievements stands alone and separate from the computational devices and aids that pre-date it. In the 18th century lex continui in natura proclaimed that nature had no discontinuities, and we tend to view historical causation in the same way. Discontinuities in history are uncomfortable: they offend against gradualism, or at least against the idea of the irreducible interconnectedness of events. The central assertion of this chapter is that core ideas evidenced in modern computing, ideas with which Turing is closely associated, emerged explicitly in the 19th century, a hundred years earlier than is commonly credited.