There are four main theories of punishment; retribution, deterrence, incapacitation and rehabilitation. The retributive theory looks back to the crime and punishes because of the crime. The remaining three all look forward to the consequences of punishment and thereby hope to achieve a reduction in crime. They are therefore often termed consequentialist or utilitarian theories. The boundaries between these theories are far from clear, containing sub-categories, many of which are perceived quite differently by different writers. To establish why it is we punish, each theory will have to be examined closely. The term retribution can be used in several senses. It can indicate vengeance or expiration, however, it is today more commonly associated with giving the offender his just deserts and using punishment as a censure or denunciation. The desire for vengeance theory is that the punishment satisfies the victim’s desire for vengeance, and the state is exacting vengeance on their behalf to prevent private retaliation. Such a view finds little support today. Expiration requires the offender to work off his guilt; he must be purified through suffering. “The essence of the expiratory view is that in suffering his punishment, the offender has purged his guilt, has ‘paid for’ his crime, and that his account with society is therefore clear.” The focus is on the past crime with the attempt to wipe the slate clean. These ideas largely stem from religious influences on our culture. However, a deeper psychological explanation has been argued to exist, underlying the offenders need for expiration. Guilt is a state of tension which gives rise to a need for the removal of this tension. From the time we are children we are conditioned to expect this relief through punishment. In R v. Williams the defendant was to be punished so that he could expiate his sins, and thus become an accepted member of society again. Whilst society may offer the chance of expiration, it obviously cannot demand it as the desire for true expiration must flow from the defendant himself. The view that has gained support, whilst theories of punishment such as deterrence and rehabilitation have come under increasing attack, is that we punish criminals primarily because they deserve it. The Criminal Justice Act 1991 followed a White Paper which proclaimed that the aim was “better justice through a more consistent approach to sentencing, so that convicted criminals get their ‘just deserts.’” Just desert theorists have tended to follow the ideas of Kant, that people deserve to be punished if they have broken the law. Furthermore, all persons owe duties to others not to infringe their rights. Justice and fairness ensure that all persons must bear the consequence of obeying the law equally. Thus punishment is necessary to remove the benefits gained by the offender. The concept of just deserts has attracted criticism as there is the suspicion that “the idea of desert cannot be distinguished from a principle of vengeance or the unappealing assertion that two wrongs somehow make a right.” Although, there are two main advantages to desert based punishment. Firstly, it imposes limits on the states power in that excessive exemplary or incapacitative sentences become unacceptable. Second, it reduces the unjustifiable sentencing disparity, as two offenders whom commit the same crime will receive similar punishments, irrespective of race, culture or background. Deterrence is the second main theory of punishment and it aims to reduce crime by the threat or example of punishment. Unlike retributive theories, deterrent theories are forward looking, concerning themselves with the consequence of punishment. Deterrence operates on several levels. Firstly, by individual deterrence it is hoped that the experience of punishment will be so unpleasant that the offender will not reoffend. In this theory, the task of the sentencer is to look to the future and select the punishment that will have the greatest impact on the individual. It is argued that every time a crime is committed the theory of deterrence is weakened. Moreover, reconviction highlights the failure of the previous sentence. Andrew Ashworth sates that where a “former prisoner is not reconvicted within two years, one cannot tell whether the explanation for that is the rehabilitative effect of custody, or its deterrent effect upon him, or a decision taken independently by the offender, or simply good luck in avoiding detection.” Under the theory of general deterrence it is the threat of punishment that deters people from committing crimes. At the legislative level, Parliament establishes penalties to threaten those who might contemplate committing a crime. At the sentencing level, offenders are punished in order that others will be discouraged from committing crimes. Thus, punishment is held up as an example of what will happen to those who engage in similar activities. When a specific crime is on the increase or attracted much publicity, then exemplary sentences may be imposed to attempt to prevent that particular crime. In Whitton , concern over the rise of hooliganism at football matches led to an exemplary sentence of life imprisonment for riotous assembly outside a football ground. The theory of general deterrence rests upon the crucial assumption that people are deterred from committing crime by the threat of punishment. It is of some significance that from the evidence on deterrence, the White Paper preceding the Criminal Justice Act 1991 concluded that “it is unrealistic to construct sentencing arrangements on the assumption that most offenders will weigh up the possibilities in advance and base their conduct on rational calculation.” Within the theory of deterrence it is possible for punishment to have a more profound subconscious effect on society. The idea of educative deterrence is that punishment of criminals builds up the habit of not breaking the law in society. For example, every time someone is punished for theft the public morality that theft is wrong is strengthened and the habit of not stealing is reinforced. The achievement of inhibitions and habits is of greater value than mere deterrence. For the reasons stated by J. Andenaes, these apply “where a person need not fear detection or punishment, and they can apply without the person even having knowledge of the legal prohibition.” However, the educative theory rests upon the premise that public morality and inhibitions against committing crimes are created and preserved by the regular punishment of others. Moreover, this is a difficult premise to test. The third main theory of punishment is the theory of incapacitation. In the case of Sargent , Lawton L.J. acknowledged “that there are some offenders for whom neither deterrence nor rehabilitation works. They will go on committing crimes as long as they are able to do so. In those cases the only protection which the public has is that such persons should be locked up for a long period.” The aim of protective sentencing is to render the offender incapable of committing more crimes. Thus, not only can it be seen as punishing the offender for past crimes, but it seeks to punish for crimes yet to be committed. In the Floud Report on Dangerous Offenders the problem of punishing people for what they are predicted to do is assessed by reference to the risk of grave harm to potential victims which must be balanced against the grave harm of unnecessary protective sentences. More recently, attempts have been made to locate incapacitative sentencing within a retributive framework. Thus, the principle of proportionality can set a ceiling beyond which punishment is impermissible. Few would doubt that there are a number of dangerous offenders for whom incapacitation may be a serious option. In fact there is much public support for cases where society needs protection. However, the lack of proportionality inherent in protective sentencing remains problematic. Therefore, the only way forward is to defend protective sentencing on desert grounds. The final theory is to punish with the aim of reforming or rehabilitating the offender. This theory is one of the most ambitious developments in penal theory. Its aim is to secure conformity though inner positive motivation on the part of the individual. As more was learned about human behaviour it was hoped that therapeutic measures could be designed which would improve the offender’s behaviour. However, with the rehabilitative ideal is the problem that proportionality suffers. Instead of looking to the past and the offence committed, the sentencer must concern himself with the future needs of the offender. Thus the chosen sentence should be the one with the best chance of bringing about the desired change. Therefore, treating like cases in a like manner has little or no part to play. Furthermore, the success of a rehabilitation programme is measured by studies of recidivism. Few of which lend much support to the idea that rehabilitation works. It is wrong to say that nothing works, what is more accurate is to state, as did Robert Martinson that “with few and isolated exceptions, the rehabilitative efforts have been reported so far have had no appreciable effect on recidivism.” The Criminal Justice Act 1991 has to some extent acted upon the notion that power over a criminals life should not be taken in excess of that which would be taken were his reform not considered as one of our purposes. Thus, the reformist ideal is not discarded but any measures designed to reform take place within the confines of the system based primarily on proportionality. Therefore, in conclusion, the main purpose of punishment is that criminals receive their just deserts. This may, obviously, have the desirable effect of stimulating law-abiding conduct and discouraging crime (educative deterrence). Moreover, this may enable the sentencer to incapacitate the dangerous and hopefully even reform them. However, these later aims are merely welcome by-products of the central retributive function of punishment.