3 Enlightenment, science and empiricism

The Enlightenment's dedication to reason and knowledge did not come out of the blue. After all, scholars had for centuries been adding to humanity's stock of knowledge. The new emphasis, however, was on empirical knowledge: that is, knowledge or opinion grounded in experience. This experience might include scientific experiments or firsthand observation or experience of people, behaviour, politics, society or anything else touching the natural and the human. For any proposition to be accepted as true, it must be verifiable, capable of practical demonstration. If it was not so verifiable, then it was an error, a fable, an outright lie or simply a hypothesis. Although Enlightenment thinkers retained a role for theoretical or speculative thought (in mathematics, for example, or in the formulation of scientific hypotheses), they took their lead from seventeenth-century thinkers and scientists, notably Francis Bacon (1561–1626), Sir Isaac Newton and John Locke (1632–1704), in prioritising claims about the truth that were backed by demonstration and evidence. In his ‘Preliminary discourse’ to the Encyclopédie, d'Alembert hailed Bacon, Newton and Locke as the forefathers and guiding spirits of empiricism and the scientific method. To any claim, proposition or theory unsubstantiated by evidence, the automatic Enlightenment response was: ‘Prove it!’ That is, provide the evidence, show that what you allege is true, or otherwise suspend judgement.

It would be difficult to exaggerate the prestige which Newton's discoveries gave to the method whereby he arrived at them. Empiricism worked and was seen to work. It was verifiable; the experiments could be repeated time and again, always with the same result and revealing the same connection between cause and effect, the same immutable underlying ‘laws’ of nature in operation. In the well-known epigram of Alexander Pope, Newton's elevated status is clear:

Both the philosophical and practical advantages of Newtonianism and the scientific method were further and vividly brought out in the second half of the eighteenth century with startling advances in industrial technology. The Encyclopédie was explicitly inclusive of ‘the arts’, and in the eighteenth century these included technology and the mechanical arts. In his article ‘Stocking-machine’ in the Encyclopédie, lavishly illustrated in one of the supplements, Diderot showed how mechanisation ingeniously multiplied human efforts and thus facilitated human comfort and convenience. In Britain, improving on James Hargreaves's spinning-jenny (1764), Richard Arkwright with his water-frame (1768) and Samuel Crompton with his mule (1779) applied technology to the mass production of cloth by steam-driven machines. Such labour-saving devices, so manifestly advantageous, illustrated the triumph of scientific method and Enlightenment rationalism. Empiricism was thus central to the Enlightenment's desire to establish knowledge on firm foundations rather than blindly following authority, convention, tradition and prejudice. Where such foundations were lacking, where the speaker or writer could not satisfactorily respond to the challenge to ‘prove it’, it was clear that their claims should be met with a strong measure of scepticism.

Empiricism was applied to every aspect of human thought and activity. The Scottish philosopher David Hume's approach to the issues of suicide and the immortality of the soul is suffused by a respect for the demands of empirical reasoning and the related question, ‘Is such-and-such a factual claim probable in the light of common human experience?’ Hume dismissed with evident relish all speculative reasoning not based on verifiable fact. By speculative reasoning he meant, above all, that based on religious revelation, private intuition, theological dogma and the authority of the churches. The explorer Mungo Park and his close associate, the scientist and botanist Joseph Banks (1743–1820), shared this concern with close observation as the basis of our knowledge of the world, though Park was a believing and practising Christian. The scientific method was happily applied in the eighteenth century by many believers and men of the cloth, who, unlike Hume, felt that science reinforced rather than undermined the reasonableness of religious belief. Cugoano's arguments against slavery were also based on appeals to observation and experience, inviting the reader to judge for himself. Landscape artists and theorists both amateur and professional, such as William Gilpin (1724–1804) and John Constable (1776–1837), paid greater attention to direct observation and sketching of their subject rather than simply the careful imitation of revered masterpieces of the past. This practice was not an eighteenth-century invention, but firsthand studies of the landscape assumed greater importance in relation to studio work as the century progressed. Seeing and thinking for yourself and drawing on the evidence of the five senses were central to the Enlightenment mindset.

Specialisation of knowledge was less common in the eighteenth century than it is today, and the boundaries of what we now call ‘science’ were defined relatively late in the nineteenth century. For the philosophes and Enlightenment men and women generally, an interest in botany or chemistry might sit happily alongside intellectual enquiry into politics, art, literature and economics. As well as being an explorer, Mungo Park, who had qualified as a surgeon, had a keen interest in natural history and in the system of the Swedish naturalist Carl von Linnaeus (1707–78) for the classification of plants. It was common to speculate on connections between science and other subjects such as human nature, religion and morality. There were many debates, for example, on the workings of the nervous system in relation to the question of how far we are responsible for our actions, or on the physical laws of the natural world in relation to the nature or indeed the existence of God.

The Royal Institution in London played a large part in making science a fashionable concern of the educated elite. In the Midlands the Unitarian minister, radical thinker, chemist and inventor of soda water Joseph Priestley (1733–1804) conducted experiments that spread knowledge of experimental science throughout society. A supporter of the French Revolution, he saw the potential of science to contribute to political and religious change. The French scientist Antoine Lavoisier (1743–94) set in motion a development known as the ‘chemical revolution’, which changed the way in which chemical elements were classified, as well as recognising the key role of oxygen in chemical processes. Both the French Revolution and Napoleon's regime perpetuated the Enlightenment emphasis on science as a means of acquiring mastery over the natural world: intellectual power was harnessed in the service of the state. By affording access to the general laws governing the physical universe, science was the strong arm, as well as the foundation, of reason. As Romanticism gained ground in the wider culture, science was sometimes perceived as an antidote (or a salutary, sobering, cold shower) to the feverish ravings of feeling or the imagination. To Enlightenment thinkers, science was much more than a set of topics to be studied. It represented the unshakeable triumph of the empirical method, the crucial testing of hypotheses against evidence, that could be applicable to all aspects of human enquiry, including questions of morality and religion.

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Transcript: Advances in medicine

TONY LENTIN

One of the greatest achievements of the enlightenment was the advance in medicine the most successful was inoculation against smallpox. Inoculation was banned by the church but the Philosoph’s took up the cause

PROF CHRISTOPHER LAWRENCE

The promoters of inoculation in France were the Philosophs Voltaire’s English Letters appear in 1734 and are a very early example of the great valuation that the Philosophs put upon his technique.

The article in the Encyclopaedia is enormously long in comparison to the apparently insignificant nature of the procedure.

One of the things about inoculation that must have appealed to the Philosophs was it’s simplicity, this wasn’t an arcane and complex procedure. It could be done by the local surgeon the local physician without any great preparation.

What they would have used would have been a lancet. All the surgeon or physician needed to do was take some dried material from an old smallpox wound, the case would be a few days old perhaps. Take it maybe on the end of your scalpel, you could then apply it immediately to another patient or dry it and apply it at a later time.

TONY LENTIN

Inoculation worked the prestige of the Philosophs increased, science was gaining ground. The next advance championed by the Philosophs was in surgery.

PROFESSOR CHRISTOPHER LAWRENCE

Perhaps the most famous of all eighteenth century operation was lithotomy cutting for the stone.

For reasons that are not entirely clear bladder stones, bladder calculi seemed to have been incredibly common in the seventeenth and eighteenth century.

Benjamin Franklin had one Samuel Pepys had one. Operations for bladder stone were very common. This figures very large in the plates in Encyclopaedia no wonder because French surgeons regarded themselves as having perfected what was known as the lateral operation for the stone.

In this operation a surgeon would cut into the bladder. The pa the patient would be seated on a chair, his or her legs strapped up and incision is made from below.

A long knife might then be pushed into the bladder or, in this case a hidden knife, this would be inserted into the bladder through the initial opening and then a knife appears and a track can be cut.

A dilator of some sort would need to be passed and then one would hope after about twenty seconds you could get your lithotomy forceps into the bladder, find the stone, take hold of it and pull it out.

An expert surgeon would hope to perform this operation in thirty-seconds. If you were unlucky it might last a minute and a half or worse. Obviously it was an operation erm that was dangerous but some Paris surgeons claimed success rates as high as ninety-two per cent.

TONY LENTIN

Medicine had immediate and obvious benefits and it’s success demonstrated the victory of scientific method and rational thought.

End transcript: Advances in medicine

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Advances in medicine