Penology is the study of penalties (from the Greek penalty), although in its broadest sense it is also concerned with the consequences and merits of attempting to deal with various kinds of conduct by criminal prohibition (‘criminalizing’). It includes not only the study of penal codes of law, but also the investigation of ways in which penal codes are applied by courts in practice, and the manner in which each type of penal measure is applied. For example, even when a penal code appears to oblige courts to pronounce a sentence (such as imprisonment for life in the case of murder), there are ways of avoiding this (such as convicting the offender of a less serious charge of homicide); most penal systems provide legal devices by which a sentence of imprisonment can be terminated before its nominal end. Penologists are interested in all such expedients, and in the criteria which are used by courts, administrators and other personnel to make distinctions between offenders, whether for such purposes or for other reasons. Other reasons may include the belief that certain types of offenders are more likely than others to respond to certain regimes, or that some prisoners are so dangerous that they must be given special sentences, detained longer than is normal for the offence, or given freedom only under specially strict conditions.
An important task of penologists is to provide answers to the question ‘How effective is this (or that) measure?’ Effectiveness is usually assessed by reconvictions or rearrests, although this is not without problems. For example it cannot take account of offences of which the offender is not suspected; the follow-up period must be substantial; in some jurisdictions rearrests or reconvictions for minor offences are not recorded centrally. The most serious problem, however, is the difficulty of being sure that offenders who remain free of rearrests during the follow-up period would not have remained free if otherwise dealt with: for example, if merely discharged without penalty. In consequence, follow-up studies must usually be content with comparing the reconviction rates after different measures. Even so, they have to take into account the fact that courts are selective, and do not allocate offenders randomly to different measures (a few random allocation studies have been achieved, but only for rather specific groups of offenders or offences: see Farrington 1983). The criteria used to allot offenders to different measures may themselves be associated with higher or lower reconviction rates. For instance, the more previous convictions that individuals have, the more likely they are to be reconvicted, quite apart from any effect which a sentence may have on them. Again, offenders whose offences usually involve theft, burglary, drunkenness or exhibitionism are more likely to be reconvicted than those who commit serious sexual offences or personal violence. Statistical devices have to be used to allow for this, for example, by subdividing samples into high-, medium- and low-risk groups. When such precautions are taken, the differences between reconviction rates following such different measures as imprisonment, fines and probation have tended to disappear, and the choice of sentence therefore seem to make no difference to a person’s likelihood of reconviction; or not enough difference to justify expensive measures. But this is now regarded as an exaggeration: some types of offenders do respond to some techniques (McLaren 1992).
In any case, other possible aims of penal measures have to be taken into account. Psychiatrists, for example, usually regard themselves as primarily concerned with the mental health of those committed to their charge by criminal courts; and social workers—including many probation officers—regard their clients’ financial and family problems as more important than their legal transgressions.
Whether these views are accepted or not, some penal measures are valued as general deterrents, in the belief that even if they do not often affect the conduct of those who have experienced them, they discourage potential offenders who have not yet committed offences (Beyleveld 1980). The efficacy of general deterrents has been exaggerated, for example, by the supporters of capital punishment: statistical comparisons of jurisdictions which have abolished or retained the death penalty, or of decades in the same jurisdiction preceding and following abolition, suggest that the substitution of long periods of imprisonment for the death penalty does not affect rates of intentional homicide. In plain terms, potential murderers who think before they kill are as likely to be deterred by ‘life’ as by death. Whatever the penalty, however, its deterrent efficacy depends to a great extent on people’s own estimates of the probability of being detected and punished. For some people this seems immaterial; but they tend to be those who commit impulsive or compulsive crimes.
Another aim of some penal measures is simply to protect other people against a repetition of the offence by the offender concerned, usually by some degree of incapacitation. Incapacitation may take the form of long detention, disqualification from certain activities (such as driving or engaging in certain occupations) or surgery (for example, castration for rapists). The more severe types of incapacitating measures are controversial, the chief objection being that the probability of offenders’ repeating their offence seldom approaches certainty, and is often less than 50:50 (Floud and Young 1981).
This illustrates a more general tendency to acknowledge the relevance of jurisprudence for penology. Scepticism about the efficacy of corrective or deterrent measures, together with the excessive use of very long detention in the name of therapeutic treatment, has revived the classical emphasis on the need for penalties to reflect the culpability of the offender. The underlying Kantian morality of this was never quite abandoned by jurists in the former West Germany; but the revival of it in the USA and Scandinavia is an important phenomenon, although lacking the sophistication of German jurists (Von Hirsch 1976).
English judges—and, quite independently, Durkheimian sociologists—have contributed yet another notion. Without necessarily accepting the retributive view (which has both difficulties and dangers) they hold that penalties have an important expressive or symbolic function, declaring publicly the moral disapproval with which most people regard harmful offences (Walker 1978). Some English judges have even stated that an important task of sentencers is to lead public opinion, although this seems to exaggerate the attention and respect which the public pay to sentences (Walker and Marsh 1984). More tenable is the proposition that sentences reflect people’s disapproval: the question is whether sentencers are selected or trained so as to be sure of reflecting the views of the law-abiding public, particularly in societies with heterogeneous moralities.
Other subjects in which penologists have interested themselves are the rights of offenders, especially those recognized by conventions (such as those of the United Nations or European Union); the protection of offenders against avoidable stigma; and the rights of victims to compensation, whether from the state or the offender, and to other forms of care.
Nigel Walker
University of Cambridge
References
Beyleveld, D. (1980) A Bibliography on General Deterrence Research, Westmead.
Farrington, D.P.F. (1983) ‘Randomised experiments on crime and justice’, in M.Tonry and N.Morris (eds) Crime and Justice, vol. 4, Chicago.
Floud, J. and Young, W. (1981) Dangerousness and Criminal Justice, London.
McLaren, K. (1992) Reducing Reoffending: What Works Now, Wellington, NZ.
Von Hirsch, A. (1976) Doing Justice, the Choice of Punishments: Report of the Committee for the Study of Incarceration, New York.
Walker, N. (1978) ‘The ultimate justification’, in C.F.H. Tapper (ed.) Crime, Proof and Punishment: Essays in Memory of Sir Rupert Cross, London.
Walker, N. and Marsh, C. (1984) ‘Do sentences affect public disapproval?’, British Journal of Criminology.
penalty), although in its broadest sense it is also concerned with the consequences and merits of attempting to deal with various kinds of conduct by criminal prohibition (‘criminalizing’). It includes not only the study of penal codes of law, but also the investigation of ways in which penal codes are applied by courts in practice, and the manner in which each type of penal measure is applied. For example, even when a penal code appears to oblige courts to pronounce a sentence (such as imprisonment for life in the case of murder), there are ways of avoiding this (such as convicting the offender of a less serious charge of homicide); most penal systems provide legal devices by which a sentence of imprisonment can be terminated before its nominal end. Penologists are interested in all such expedients, and in the criteria which are used by courts, administrators and other personnel to make distinctions between offenders, whether for such purposes or for other reasons. Other reasons may include the belief that certain types of offenders are 
