Sherlock Holmes: scientific detectiveLaura J. Snyder

St John’s University, 8000 Utopia Parkway, Jamaica, NY 11439, USA

Sherlock Holmes was intended by his creator, Arthur

Conan Doyle, to be a ‘scientific detective’. Conan Doyle

criticized his predecessor Edgar Allan Poe for giving his

creation – Inspector Dupin – only the ‘illusion’ of

scientific method. Conan Doyle believed that he had

succeeded where Poe had failed; thus, he has Watson

remark that Holmes has ‘brought detection as near an

exact science as it will ever be brought into the world.’

By examining Holmes’ methods, it becomes clear that

Conan Doyle modelled them on certain images of

science that were popular in mid- to late-19th century

Britain. Contrary to a common view, it is also evident

that rather than being responsible for the invention of

forensic science, the creation of Holmes was influenced

by the early development of it.

Sherlock Holmes made his first appearance in A Studyin Scarlet, published in 1887 (Figure 1). Early in theiracquaintance, Watson reads Holmes’ article ‘The Book ofLife’, in which Holmes describes ‘The Science of Deductionand Analysis’. This science requires the ability to reasonbackwards from present effect to absent cause, or from thepresent to the past. Thus, Holmes explains that ‘From adrop of water.a logician could infer the possibility of anAtlantic or a Niagara without having seen or heard of oneor the other.’ When Watson – unaware that Holmes wrotethe article – declares this to be nothing but ‘ineffabletwaddle’, Holmes explains that, on the contrary, this typeof reasoning has practical application in his work as a‘consulting detective’.

Holmes and the historical sciences

Holmes’ description of his method of reasoning is similarto that used in the ‘historical’ or ‘palaetiological’ sciences ofpaleontology, archeology and geology, which by that timehad captured the imagination of the literate public. In oneof his popular lectures on science, Thomas H. Huxleylauded the skill of Georges Cuvier, who had been able toreconstruct ‘entire animals from a tooth or perhaps afragment of bone’ [1]. More recently, the comparativeanatomist Richard Owen (Figure 2) had been celebratedfor reconstructing an extinct bird from a six-inch longpiece of bone [2]. In the historical sciences, Huxleyexplained, the scientist must ‘strive towards the recon-struction in human imagination of events which havevanished and ceased to be’ [3]. Using present clues – bonefragments, fossils and geological strata – the scientistreasons back to absent organisms and past time periods.

Corresponding author: Laura J. Snyder (snyderl@stjohns.edu).Available online 7 August 2004

www.sciencedirect.com 0160-9327/$ - see front matter Q 2004 Elsevier Ltd. All rights reserved

Thus, the scientist requires the power of making‘retrospective prophesies’.

In ‘TheFiveOrangePips’,Holmesdescribeshismethod inmuch the samewayasHuxleyhad characterized themethodof the historical sciences, including the reference to Cuvier:

The ideal reasoner.would, when he had once been showna single fact in all its bearings, deduce from it not only allthe chain of events which led up to it but also all the resultswhich would follow from it. As Cuvier could correctlydescribe a whole animal by the contemplation of a singlebone, so the observer who has thoroughly understood onelink in a series of incidents should be able to accuratelystate all the other ones, both before and after.

Review Endeavour Vol.28 No.3 September 2004

Figure 1. The first appearance of Arthur Conan Doyle’s ‘A Study in Scarlet’. The

story featured on the front cover of Beeton’s Christmas Annual in 1887. Image

reproduced courtesy of The Lilly Library, Indiana University, Bloomington, IN, USA.

. doi:10.1016/j.endeavour.2004.07.007

Figure 2. Richard Owen (1804–1892). Image supplied by, and reproduced with

permission from, The Wellcome Library, London.

Figure 3. Sir Arthur Conan Doyle, from a portrait by Sidney Paget in 1897. Image

supplied by the National Portrait Gallery, London (www.npg.org.uk) and repro-

duced with permission of Charles Foley, on behalf of the Estate of Dame Jean

Conan Doyle.

Review Endeavour Vol.28 No.3 September 2004 105

Holmes himself often demonstrates this ability. Forexample, in the opening pages of The Hound of theBaskervilles, Holmes treats Dr Mortimer’s walking stickas a kind of fossil remain, using it to reconstruct an absent(although, in this case, living) person.

Conan Doyle (Figure 3) was familiar with Huxley’swork, referring to him in later years as one of the ‘chiefphilosophers’ of the time [4]. But Conan Doyle had alsolearned this method of reasoning first-hand while study-ing medicine at Edinburgh. He famously reported that histeacher Joseph Bell was the inspiration for SherlockHolmes. In a gramophone recording made towards the endof his life, Conan Doyle explained that ‘I thought I wouldtry my hand at writing a story where the hero would treatcrime as Dr Bell treated disease.’ As Cuvier couldreconstruct the anatomy and environment of an animalfrom fossilized remains, so could Bell reconstruct apatient’s profession, hometown and past history from hisown initial observations of the patient’s dress, accent,habits and symptoms. In an often-reported case, Belldetermined within moments of meeting a patient that hehad been recently discharged as a non-commissioned

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officer from a Highland regiment stationed in Barbados.‘You see, gentlemen’, he explained to his awed students,‘the man was respectful, but did not remove his hat. Theydo not in the army, but he would have learned civilianways had he been long discharged. He has an air ofauthority and is obviously Scottish. As to Barbados, thecomplaint is elephantiasis, which is West Indian and notBritish’ [5]. In A Study in Scarlet, when Holmes firstmeetsWatson, he concludes thatWatson has recently beenin Afghanistan by using the same kind of reasoningbackwards.

Rules to ‘interpret Nature’

Holmes also describes various ‘rules of deduction’ that heuses in reasoning backwards. These rules reflect commonimages of the work of Francis Bacon, the 17th-centuryphilosopher of science whose writings became extremelypopular in 19th-century Britain. Conan Doyle explicitlysignals his appropriation of Bacon’s method by havingHolmes remark in A Study in Scarlet that the detectivemust reason as he does in order to ‘interpret Nature’, aphrase famously used by Bacon in defining his owninductive method. (Holmes’ characterization of thismethod as ‘the science of deduction’ rather than ‘thescience of induction’ is consistent with common usage ofthe term ‘deduction’ during the 19th century, when it wasoften used as a synonym for the more general term‘inference’).

One popular view of Bacon’s method was expressed byT.B. Macaulay in an essay originally published in 1837 [6].

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Macaulay’s interpretation suggested that Bacon’s methodrequired that facts be collected blindly, without anypossible theory in mind. Once these facts are collected,the ‘interpreter’ of Nature plugs them into tables ofpresence, absence and variation, andmechanically applieseliminative induction. After this exclusion is performed,what remains is the truth. In his autobiographical workThrough the Magic Door, Conan Doyle claims thatMacaulay’s Essays [6] were among his favorite readingmaterial when he was young; therefore, it is most probablethat he read Macaulay’s essay on Bacon.

A central aspect of Macaulay’s image of Bacon isreflected in Holmes’ famous and often repeated claimthat ‘when you have excluded the impossible, whateverremains, however improbable, must be the truth’ (‘TheAdventure of the Beryl Coronet’). The importance ofreaching a conclusion by eliminating all but one possibilityis noted in several of the works. For example, in ‘TheAdventure of the Blanched Soldier’, Holmes uses theeliminative method to solve the mystery of the incarcera-tion of Godfrey Emsworth by his family. Holmes realizesthat there are only three possible reasons for Godfrey’sfamily to hide him as they have done. He eliminates thefirst two alternatives, by seeing that they are inconsistentwith some of the facts of the case, and then concludes that‘there remained the third possibility, into which, rare andunlikely as it was, everything seemed to fit.’ Indeed, hewas right: the boy was thought to have leprosy, and he washidden to prevent his being sent to a leper home.

Holmes also expresses a view similar to Macaulay’sreading of Bacon when he notes that facts must becollected before theories are formed. ‘It is a capitalmistake’, Holmes remarks, ‘to theorize before one hasdata. Insensibly one begins to twist facts to suit theories,instead of theories to suit facts’ (‘A Scandal in Bohemia’).At times, he even suggests that the detective mustapproach the facts with a tabula rasa, a mind completelydevoid of ideas or theories: ‘We approached the case.withan absolutely blank mind, which is always an advantage.We had formed no theories. We were simply there toobserve’ (‘The Adventure of the Cardboard Box’). In TheHound of the Baskervilles, Watson is sent off to Devonshireto report all the facts back to Holmes, who claims to be inLondon synthesizing these facts into a theory. ‘I will notbias your mind by suggesting theories or suspicions,Watson.I wish you simply to report facts in the fullestmanner to me, and you can leave me to do the theorizing.’

However, an alternative image of Bacon’s method wasalso popular during the 19th century, and is equallyreflected in Holmes’ ‘rules of deduction’. The polymathWilliam Whewell, among others, characterized Bacon’smethod in amore complex and accurate way [7]. This moreaccurate reading of Bacon’s method recognized that Bacondid not advocate the ‘blind’ collection of facts. Rather,Bacon famously criticized the ‘men of experiment’ or the‘empirics’ who collect facts blindly, like ants collect matter.Bacon recognized that fact collection and theorizing occursimultaneously to some extent. Holmes, too, often allowsthis. Thus, for example, although Holmes tells Watson inThe Hound of the Baskervilles that he will remain inLondon forming theories with the ‘blind’ facts Watson

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sends him, he is in fact in Devonshire collecting his ownfacts and devising a theory at the same time.

Another way in which Holmes deviates from Macau-lay’s image of Bacon is in the importance he gives toimagination. Holmes often admonishes the inspectors ofScotland Yard for lacking this quality. In terms of factcollection, Holmes notes, they ‘lead the world for thor-oughness and method’; yet they are often unsuccessfulbecause of their ‘occasional want of imaginative intuition’(‘The Adventure of the Three Gables’). Importantly,although he speaks of imagination, Holmes is not endor-sing the use of guesswork to formulate a hypothesis. Onthe contrary, Holmes asserts that ‘I never guess. It is ashocking habit – destructive to the logical faculty’ (‘TheSign of Four’). In The Hound of the Baskervilles, when DrMortimer claims that ‘we are coming now rather into therealm of guesswork’, Holmes corrects him: ‘Say, rather,into the region where we balance probabilities and choosethe most likely. It is the scientific use of the imagination,but we always have some material basis on which to startour speculations.’ What he means by the ‘scientific use ofthe imagination’ – a phrase popularized by John Tyndallin an 1870 lecture – is not unfettered guesswork butrather, as the reference to ‘balancing probabilities’ makesclear, a series of inferences [8]. His ‘rapid deductions’might be ‘as swift as intuitions’, but they are ‘alwaysfounded on a logical basis’ (‘The Adventure of the SpeckledBand’). In The Hound of the Baskervilles, Holmes’conclusion that the warning letter to Sir Henry wascomposed in a hotel seemed to Mortimer to be guesswork,but was actually based on observation and inference.Holmes realizes that the address was written with a penthat had run dry three times, indicating that there wasvery little ink both in the pen and in the ink bottle. Thiswould have been common in hotel rooms, but not in theprivate homes of the well educated, who would be the mostlikely to cut words from The Times. Thus, the imaginativeintuition he chides the police for lacking seems to be acreative aptitude for making logical inferences from thefacts.

These aspects of Holmes’ method resemble the image ofBacon depicted by Whewell. As Whewell notes, Bacondecisively rejects guesswork as a route to hypotheses. Buthe also denies that mere eliminative inference is enough.Rather, Bacon emphasizes that conclusions should bereached by chains of inferences of various kinds. AlthoughBacon, as characterized by Whewell, does not explicitlyindicate a role for ‘imagination’, he does describe one of thenecessary forms of reasoning as requiring ‘rather asagacity, and a kind of hunting by sense, than a science’[9,10]. Although there is no direct evidence that ConanDoyle readWhewell, he does seem to have been influencedby the image of Bacon depicted byWhewell, as well as thatportrayed by Macaulay.

Holmes: the ‘father of scientific criminal detection’?

In A Study in Scarlet, Dr Watson first meets Holmes in alaboratory, where Holmes has been experimenting onbloodstains.

Figure 4. This illustration of Sherlock Holmes depicts him with a magnifying glass,

indicating his scientific approach to crime detection and was the frontispiece to the

first edition of ‘A Study in Scarlet’ (Illustration by D.H. Friston). Image reproduced

courtesy of The Lilly Library, Indiana University, Bloomington, IN, USA.

Review Endeavour Vol.28 No.3 September 2004 107

I’ve found it! I’ve found it,’ he shouted to my companion,running towards us with a test-tube in his hand. ‘I havefound a re-agent which is precipitated by haemoglobin,and by nothing else.. [I]t is the most practical medico-legal discovery for years. Don’t you see that it gives us aninfallible test for blood stains?.. [T]he old guaiacum testwas very clumsy and uncertain..Had this test beeninvented, there are hundreds of men now walking theearth who would long ago have paid the penalty of theircrimes..

It is often claimed that passages such as this presagedthe development of the modern science of forensics, andtherefore that Conan Doyle’s invention of SherlockHolmes is responsible for the origination of this science.The criminologist Harry Ashton-Wolfe, in 1932, assertedthat ‘Many of the methods invented by Conan Doyle aretoday in use in the scientific laboratories’ [11]. Sir SidneySmith, professor of Forensic Medicine at Edinburgh,believed that ‘Conan Doyle had the rare, perhaps uniquedistinction of seeing life become true to his fiction’,referring specifically to Conan Doyle’s ‘anticipation ofmodern scientific methods of investigation’ [12]. A morerecent writer has dubbed Sherlock Holmes the ‘father ofscientific crime detection’ [13,14] (Figure 4). Howeverappealing this claim might be to fans of Sherlock Holmes,it seems that there is little evidence to support it.Although the science of forensics was still relativelyyoung by the time the Sherlock Holmes stories werewritten, it had already been developing many of theprocedures and tests that are often attributed to theimagination of Conan Doyle. It is therefore more likelythat the new science of forensics was another influenceupon the creation of Conan Doyle’s scientific detective.

Let us examine, for example, the ‘infallible’ test forbloodstains Holmes is presented as having ‘invented’. By1887, when A Study in Scarlet was published, manyresearchers already shared the desire for such a test; thisdesire was not satisfied until the turn of the 20th century,when the spectroscopic method was developed. A modernchemist has noted that the method Holmes describes – onewhich would precipitate a brownish dust and change thecolor of blood in water to mahogany – would need an acidto increase the oxidation rate, as well as a material to beoxidized. By examining the possibilities for the ‘few whitecrystals’ and the ‘drop of transparent fluid’ that Holmesuses, this chemist suggests that the ‘Sherlock Holmes test’would probably have had a sensitivity similar to theguaiacum test that Holmes derides as being ‘clumsy anduncertain’ [15]. Moreover, Holmes’ test does not dis-tinguish between human blood and the blood of animals– a problem that, by 1887, was considered an even largerconcern than the sensitivity of the blood tests currently inuse. A solution to this problem did not arise until the workof Paul Uhlenhuth in 1901 [16].

Holmes has also been credited with inventing methodsof studying ‘poisons, hand-writing, stains, dust, footprints,traces of wheels, the shape and position of wounds.’ [17].But again, many of these studies had already beeninitiated by the time Sherlock Holmes appeared on thescene. Matthieu Orfila’s 1813 Traite des poisons was used

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by doctors, lawyers and police officials throughout Europe;it was the first work of international renown on poisons.Even earlier, in 1806, a German researcher developed atest for detecting the presence of arsenic in human organs;by 1851, a method for detecting vegetable poisons hadbeen developed [18]. Before the first appearance ofHolmes, Alphonse Bertillon had been studying thescientific examination of documents. He published awork on the topic in 1889 and, some years later, put outan article on the study of handwriting [19]. During theearly years of the 19th century, the famous criminalcatcher Eugene Francois Vidocq had studied the shapeassumed by bloodstains as they fell, followed later byAlexandre Lacassagne. In the second decade of the 19thcentury Vidocq was also responsible for one of the firstrecorded instances of taking plaster casts of footprints at acrime scene. The shape and position of wounds had beendetailed in Lacassagne’s 1878 Precis de medecine [20].Other scientific forensic studies had also been undertakenbefore the creation of Holmes. In 1870, Auguste AmbroseTardieu published a treatise on the diagnosis of

Figure 5. The front cover of November 1906 issue of Collier’s magazine, by F.D.

Steele. In ‘The Norwood Builder’, Sherlock Holmes discovers an attempt to use a

fraudulent fingerprint to frame an innocent man. Image supplied by, and

reproduced with permission of, The British Library (shelfmark A53).

Review Endeavour Vol.28 No.3 September 2004108

strangulation, hanging and choking deaths [21]. By 1880,Henry Faulds had suggested in a letter to Nature thatfingerprints could be used to identify criminals; a systemof fingerprint identification was established in ScotlandYard by 1901 (five years before Holmes used a forgedthumbprint in the plot of “The Norwood Builder”)(Figure 5) [22]. The first use of forensic ballistics in acourt case occurred in 1784, and several detailed studies ofballistics were conducted during the second half of the19th century [23]. Sherlock Holmes may have been thefirst to write a ‘treatise on tobacco ash’ (A Study in Scarletand ‘The Sign of Four’), but his doing so reflected a spirit ofscientific inquiry that was already being applied tocriminal detection. Conan Doyle was exposed to thisresearch while in medical school; we know that heattended lectures on crime and criminals by Sir HenryLittle-John, who was the Police Surgeon of Edinburgh aswell as the Professor of Medical Jurisprudence at theuniversity [24].

Conclusion

Rather than inventing forensic science, the Holmes storiesinstead presented the ‘science of criminal detection’ in a

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positive light in Britain. This was particularly importantafter the 1859 Smethurst case, in which a leadingtoxicologist had been forced to admit that his earlierfindings of arsenic in the tissues of a dead woman – whichhad led to the verdict that Thomas Smethurst was guiltyof murder by poisoning – had been mistaken. Anindependent body of specialists later recommended theacquittal of the alleged murderer. After this, forensicscience was viewed with suspicion by the British public forhalf a century [25,26]. By creating a ‘scientific detective’who could demonstrate the logical steps leading to hisinvariably correct conclusions, Conan Doyle gave to thepublic a criminal catcher they could trust. Thus, SherlockHolmes did not invent forensic science, but he probablydid more than any other person, fictional or not, to portrayit as a valuable tool in criminal detection.

References

1 Huxley, T.H. (1896) On the method of Zadig. In Collected Essays(Vol. IV), p. 18, D. Appleton (New York, NY, USA)

2 Rupke, N.A. (1994) Richard Owen, Victorian Naturalist, YaleUniversity Press pp. 346–414

3 Huxley (1896), p. 94 Conan Doyle, A. (1924) Memories and Adventures, Hodder and

Stoughton5 Liebow, E. (1982) Dr. Joe Bell, Model for Sherlock Holmes, Bowling

Green University Popular Press6 Macaulay, T.B. (1877) Lord Bacon. In Critical and Historical Essays:

Contributions to the Edinburgh Review, pp. 346–414, LongmansGreen (London, UK)

7 Whewell, W. (1857) Spedding’s complete edition of the works of Bacon.In Edinburgh Review 106, 287–322

8 Tyndall, J. (1871) The scientific use of the imagination. In Fragmentsof Science for Unscientific People: A Series of Detached Essays,Lectures and Reviews, pp. 127–163, D. Appleton (New York, NY, USA)

9 Bacon, F. (1858–1861) The Works of Francis Bacon (Vol. 4)(J. Spedding et al., eds.) Longmans, p. 421

10 Snyder, L.J. (1999) Renovating the Novum Organum: Bacon, Whewelland Induction. Studies in History and Philosophy of Science 30,531–557

11 Cited in Berg, S.O. (1970) Sherlock Holmes, father of scientific crimedetection. The Journal of Criminal Law, Criminology and PoliceScience 61, pp. 446–452 (op. cit. p. 446)

12 Smith, S. (1959) Mostly Murder, Harrap (Edinburgh, UK)13 Berg, S.O. (1970), pp. 446–45214 Nardon, P. (1967) Conan Doyle: A Biography, (Partridge, F. trans.),

Holt, Rinehart and Winston15 Gerber, S.M. (1983) A study in scarlet: blood identification in 1875. In

Chemistry and Crime: From Sherlock Holmes to Today’s Courtroom(Gerber, S.M. ed.), pp. 31–35, American Chemical Society (Columbus,OH, USA)

16 Thorwald, J. (1965) The Century of the Detective (Winston, R. andWinston, C. trans.), Harcourt, Brace and World

17 Cited in Berg, S.O. (1970), p. 446)18 Thorwald, J. (1965), pp. 267–30019 Rhodes, H.T.F. (1968) Alphonse Bertillon, Father of Scientific Detec-

tion, Greenwood (Westport, CT, USA), p. 12620 Smyth, F. (1980) Cause of Death: The Story of Forensic Science, Van

Nostrand Reinhold, p. 146 and p. 18421 Thorwald, J. (1965), p. 16122 Cole, S.A. (2001) Suspect Identities: A History of Fingerprinting and

Criminal Investigation, Harvard University Press, pp. 73–9423 See Smyth, F. (1980), pp. 72–75 and Thorwald, J. (1965), pp. 417–42024 Jones, H.E. (1904) The original of Sherlock Holmes. Collier’s January

9, pp. 14–2025 Smyth, F. (1980), pp. 25–2626 Thorwarld, J. (1965), p. 177