George Eleftheriades and Michael Selvanayagam, researchers at the University of Toronto, have designed and tested a new approach to invisibility cloaking. Their method involves surrounding an object with miniature antennae emitting an electromagnetic field that cancels out waves reflecting back from the cloaked object. Although their tests showed the cloaking system to work with radio waves, they see no reason why, as the necessary antenna technology matures, it could not also work with light waves.

All this opens the way for a Harry Potter-style invisibility cloak that is thin, scalable, and adaptable to different types of objects. Some of the uses being touted for this quasi magical cloak include hiding military vehicles and conducting surveillance operations. But what if the cloak falls, as it surely will, into the wrong hands? Have the scientists really thought through the consequences? The infamous banker Bob Diamond spoke of ethics as ‘what you do when nobody’s looking’. If bankers, politicians, and even churchmen can no longer be trusted to do the right thing, then who can? But beyond this, the cloak of invisibility raises important questions about human nature: do intelligent people do the right thing because it is the right thing or because they fear being caught, judged, and punished? More fundamentally, is man innately good, under the direction of his conscience and sense of guilt, or is his restraint rather the product of fear and coercion instilled by a Hobbesian social contract that serves to keep him in check?

In Greek mythology, the Cap of Invisibility or Helm of Darkness is a helmet or cap variously worn by Athena, Hermes, and Perseus to make themselves invisible to gods, heroes, monsters, and men. In Book II of the Republic, Plato discusses the Ring of Gyges, which, according to legend, makes its bearer invisible. The ring was once given to the shepherd Gyges who used it to seduce the Queen of King Candaules and thereby usurp the throne of Lydia. In the Republic, the character of Socrates asserts that justice is the excellence of the soul without which a man cannot live well and be happy, and, therefore, that justice is inherently desirable. However, Glaucon doubts whether to be just is always better than to be unjust. All goods, he says, can be divided into one of three classes: harmless pleasures that are desirable in themselves; goods such as gymnastics, the care of the sick, or the various ways of making money that are desirable for what they bring; and goods such as knowledge, sight, or health that are desirable both in themselves and for what they bring. To which of these three classes does justice belong?

Socrates replies that justice belongs to the third class, but Glaucon points out that most people would disagree and place it firmly in the second class. Indeed, most people think that to do injustice is good, but that to suffer injustice is evil; as the evil outweighs the good, they agree among themselves not to do injustice. If a just man got hold of the Ring of Gyges, he would most certainly behave unjustly, proving that he is just only because he is weak and fears retribution, and not because justice is desirable in itself. The truly just man who cares only for justice and not for the appearance of justice will be thought unjust and suffer every kind of evil until the day he finally understands that he should not be, but only seem, just. In contrast, the unjust man who is resourceful enough to seem just will be thought just and always get the better of everyone and everything. Adeimantus adds that when people praise justice, they praise it for what it brings rather than for itself. Realizing this, the superior man devotes himself not to justice itself but only to its appearance.

Adeimantus claims that he does not truly believe his argument, but is nonetheless pressing it to provoke Socrates into taking its other side and demonstrating that justice is desirable in and of itself. As part of his lengthy reply, Socrates famously conjures up an idealized Republic to help him define justice (or, as he puts it, “locate justice within the State”). After having defined justice in the state and justice in the individual, Socrates asserts that the just man orders his inner life in such a way as to be his own master and his own law. The soul of such a man can be said to be healthy, for justice and injustice are to the soul as health and disease are to the body: virtue is the health and the beauty of the soul, vice its disease and debility. If justice is the health of the soul, and if health is desirable in and for itself, then, by analogy, justice too is desirable in and for itself.

This is as far as Plato gets in the Republic. Notice that his conclusion that justice is intrinsically desirable does not in itself answer the original question, which was whether an intelligent person would still behave justly if he no longer feared being caught and punished. From Plato’s other writings, the answer is surely yes, even if Plato defines ‘intelligent’ in such a way that only he and some of his friends at the Academy actually meet the criteria. These select men are, of course, the famous philosopher-kings.