A fortnight ago Magnus Carlsen - the reigning world chess champion - lost a match against a 19-year old American called Hans Niemann.

It was big news. But what happened next tore the chess community apart. Carlsen pulled out of the tournament and left a mysterious tweet.

The chess world immediately took this to mean that Carlsen was accusing his rival of cheating.   

For Carlsen, a loss to Niemann is embarrassing. The Norwegian is the highest-rated player in history. He has a record streak of 125 unbeaten matches.

Niemann denied all claims. But the story is far from over. This Monday, Carlsen left an online game against Niemann after a single move. Interviewed yesterday, the champion again implied that he was unable to comment.

Niemann has a history of cheating. He was banned from the website Chess.com after using a computer programme to trick the system. He claims he has since stopped.

Chess is no stranger to cheating. In 1978, grandmasterA title awarded to the world's very best chess players. Viktor Korchnoi accused Anatoly Karpov of cheating by receiving colour-coded yoghurt from his team. In 1985, a British man was suspended after entering a women's championship in disguise. More recently, several players have been caught using computers and tablets during bathroom breaks.

Cheating in chess is punished harshly. It damages the game. It rewards those who break agreements. It makes it hard to assess who is the best. 

In wider society, cheating disrupts fairness, the idea that we should treat people equally. As former US first lady Michelle Obama says: "success doesn't count unless you earn it fair and square."

Yet others think that cheating can be used for good. To cheat is to break the rules. If the rules are themselves unfair - such as in an oppressiveInflicting harsh and unfair treatment. society - cheating can be an act of resistanceThe refusal to comply or go along with something. . 

Cheating in war is often praised. The Greek hero Odysseus is celebrated for tricking the Trojans with his Horse¹. The AlliedRelating to Britain and its allies in World War One and Two. effort in World War TwoA global war that lasted from 1939 to 1945 and included all of the great powers. was hugely aided by secret agents who operated aside from the "rules" of war. As novelist Daniel Defoe wrote: "'Tis no sinSomething that is immoral, often in religious law. to cheat the devil."

Yes: Cheating might sometimes lead to the greater good. But the act itself remains wrong in all situations. Before cheating, you should always weigh up the effect. 

No: It all depends on the situation. To cheat someone out of a prize might be bad. But breaking the rules can lead to better outcomes. Plus, cheating well is a talent in itself.

Or... Cheating relies on the idea of fixed rules that should not be broken. This may be the case in a board game. But life itself is more complex. One side's cheating is another's genius.