When you've written a book, strange things happen. A couple of weeks ago I was interviewed by a Belgian literary magazine about The Outsider, my history of the goalkeeper, by two journalists who, while thoroughly charming, knew little about football. I ended up, I'm afraid, emotionally arguing that Jim Montgomery's save in the 1973 FA Cup final was the zenith of human achievement to date.

What I've thought about most since, though, was the question I was asked about Albert Camus, who kept goal for the University of Oran, and his line that all he knows about morality and the obligations of men he has learned from football.

It's such a familiar quote as to be a cliché; no British sportswriter would ever dream of citing it directly in a piece - I felt, I confess, a shudder repeating it here - and yet does anybody really think about what it means? Put on the spot, confronted by the question, "What did he mean by that?" from somebody from outside the sporting milieu, it's not actually that easy to answer.

I burbled on about how sport, within the circumscribed lines of the pitch, offers a simplified version of life, that the goals and the rules are much more straightforward and that it's therefore easier to see the lengths to which people would go to win.

I'm aware that my own conduct has changed as I've got older, that now, playing hockey, I no longer, as I used to, appeal for touch hits when I know the ball came off my stick last, and I tend when possible (and in a dynamic game it isn't always possible, particularly with the possibility of an advantage being played) to declare feet against myself.

And yet I also know that, if necessary, I'll cynically stop the ball with my feet to prevent a break, or step across the line of a player who has knocked the ball past me. Towards the end of last season, my team, provoked by some less-than-helpful refereeing, suffered a total breakdown in discipline in one game and was shown two red cards, three yellows, and four greens.

Forced by suspensions into captaining in the next game, I delivered a stern lecture before push-back about discipline, since when we've only picked up one card in four games: me, green-carded quite correctly for a deliberate foot. Nobody yet has called me a hypocrite.

And perhaps that's what Camus was driving at: it's not just about right and wrong. There are the laws and then there is an unspoken code of conduct. Deliberate fouls are seen as part of the game because there is an in-built sanction. Playing in the grey area between the laws is somehow worse because it contravenes the spirit of the game, that nebulous code that governs conduct that goes on in the inevitable lacunae that appear between laws.

No set of rules can ever be all encompassing, and issues such as diving, false appealing and time-wasting are almost impossible to legislate for. How, to take just one example, can a football referee realistically know whether a player running at pace is leaping to avoid being clattered by an opponent (legitimate: the law says it is a foul "to trip or attempt to trip an opponent") or deliberately manufacturing the appearance of a foul?

"If batsmen are supposed to acknowledge when they nick one behind, should their word not also be taken when they edge one onto their pads and are given out lbw?"

Cricket, in which the notion of "spirit" is enshrined within the laws, gets itself into more of a moral lather about this than any other sport. The great furore of this summer has been about Stuart Broad not walking after edging Ashton Agar to slip via Brad Haddin's gloves at Trent Bridge. There's little point revisiting an incident that has been talked about to death, other than to make three general points:

1. I wish all players in all sports would do everything they can to help umpires/referees make the right decisions, but I also recognise that, after a couple of dodgy decisions or having played against a team that appeals when they know it's not out, I probably wouldn't.

2. It's a strange morality that insists that players should walk for thick edges but not thin ones (as Haddin didn't walk when he edged Jimmy Anderson off the final ball of the match at Trent Bridge). Surely it's more callous if players go through a process of deciding they can get away with not walking because it was a thin enough nick that they could pretend to have been uncertain.

3. If batsmen are supposed to acknowledge when they nick one behind, should their word not also be taken when they edge one onto their pads and are given out lbw? Otherwise it seems a one-sided convention.

What seems a far worse crime to me is time-wasting and slow over rates, something of which England were guilty both at Old Trafford and at The Oval, something that was brought home when I flicked through Mike Rowbottom's new book Foul Play: The Dark Arts of Cheating in Sport. In it, he recalls how Brian Close was stripped of the England captaincy in 1967 because of the way his Yorkshire side, drying the ball and complaining about damp conditions, had bowled just 24 overs in 100 minutes to prevent Warwickshire chasing down 142 in a Championship match. Yet, England at times in this series - and most teams do the same in similar situations - have bowled 24 overs in an entire session.

The legislation to deal with slow play is there but it's hard to enforce. There are many excuses - field placings, the DRS, repairs to bowlers' boots, the need for sawdust to improve grip, injuries… and, of course, the batting team can delay things almost as much, as the case of Bilal Shafayat and the gloves in Cardiff in 2009 demonstrated. Slow over rates, essentially, are something that only morality - rather than laws - can deal with.

There was much talk after the Friday at The Oval of how dull the play had been and how England had a responsibility to paying spectators. You hear similar things in football after teams have defended for 90 minutes.

I disagree profoundly: sometimes sport is attritional, but that's inherent in the struggle that should underlie any contest. It's often said that sport is entertainment but that's not true: it's sport and sometimes it's entertaining, sometimes it's not.

If you want "entertainment" involving people hitting balls with consistent flamboyance, go to that Titans of Cricket thing they did at the O2 a couple of years ago. If one team wants to bowl wide of off stump and the other team wants to leave it, that's fine (even if you may question the pitch preparation that contributed to the negativity on both sides). Teams can play the game how they like; for me, it's not playing it that's problematic.

Of course if I had paid £80 for a seat on Friday I might think differently (I did pay £80 for a seat on Wednesday and ended up with a throbbing headache and minor sunburn, leading me to conclude that the biggest moral issue at The Oval is the lack of shade for those of us of a Celtic disposition).

And that, perhaps, is the third truth contained in Camus' line: that morality is to a large degree subjective, and composed of any number of shades of grey.