Children, said Plutarch, need encouragement and reason, not "blows or ill-treatment".
The UN Committee on the Rights of the Child (UNCRC), which defines corporal punishment as "any punishment in which physical force is used and intended to cause some degree of pain or discomfort, however slight", calls physical punishment "invariably degrading".
Although the use of force against someone without their consent is an offence, the physical punishment of a child is, paradoxically, lawful, and the disparity is unjustifiable. Children are not simply their parents' chattels, to be beaten at whim, and, like adults, they have basic rights.
The UN Convention on the Rights of the Child applies to Hong Kong, and Article 19 requires state parties to "take all appropriate legislative, administrative, social and educational measures to protect the child from all forms of physical or mental violence, injury or abuse".
By March, 37 states had banned corporal punishment, including Austria, Israel, Kenya, New Zealand and, most recently, Malta.
At common law, however, the "reasonable chastisement" of a child is permissible. Whilst reasonableness is hard to define, the parent usually gets the benefit of any doubt. A spanking without obvious hurt is not, generally, prosecutable, mental anguish notwithstanding, but, if injury results, such as bruises or scratches, a reasonable chastisement defence will likely fail.
In Canada, Ontario Supreme Court Justice David McCombs has noted "a growing consensus that corporal punishment does more harm than good".
Often, all an errant child requires is firm advice, perhaps allied to a non-violent punishment, such as a withdrawal of privileges. Force, however, is now the preferred option of many, and attitudes must change.
Last month, a Caritas Youth and Community Service study revealed that almost 63 per cent of children had been struck by their parents in the previous 12 months, with roughly half, or 31.1 per cent of interviewees, describing punishment that constituted physical abuse. Moreover, about 14.5 per cent of the children were considered to have been severely abused, by repeated beatings and the deliberate infliction of injury, sometimes with a belt, a stick or other hard object.
Although more than 54 per cent of the parents interviewed admitted having used physical violence, very few cases of child abuse ever make it to the courts.
There are inherent difficulties in relying on the testimony of very young children, and nobody likes to pit a child against its parent, or to undermine the family. If, however, the injuries are severe, a prosecution may be unavoidable. If not, the child may be left to fend for itself.
Whilst Hong Kong has ended institutionalised violence against children, consistency is essential. Corporal punishment is now banned in schools, in childcare centres and in the penal system, and caning is no longer a sentencing option. However, physical punishment at home is equally abhorrent, not least because it is uncontrolled and arbitrary.
In October, the UNCRC urged the authorities to "explicitly prohibit by law corporal punishment in the family, schools, institutions and all other settings", and its continued existence places children at risk.
In 2006, for example, a 10-year-old boy was found dead in a leather suitcase, into which his parents had forced him as a punishment.
The same year, an eight-year-old girl, traumatised by corporal punishment, jumped to her death.
Before another tragedy strikes, the government must recognise that force is harmful and counter-productive, and honour its international obligations.
The UNCRC has, repeatedly, lamented the absence of a children's commission to advance their rights, and, until it creates one, the government has a heightened responsibility for child welfare, including the early prohibition of corporal punishment.
Grenville Cross SC, an honorary professor of law at the University of Hong Kong, is honorary consultant to the Child Protection Institute