To Thieve, or Not to Thieve?

That is the question: whether 'tis nobler in the mind to suffer the slings and arrows of outraged guardsmen,
Or to take them unawares, and by furtive stealth sneak past them?

The suitability of the thief class to old-school campaigns is a much-debated issue in message forums and old-school blogs.  The main argument against them is that in a sword & sorcery campaign everyone is a thief, in the respect that every character's goal is to acquire other people's wealth.  Old school practice dictates that any character should be able to find and avoid traps by careful observation and canny, cautious play and the implication is that the inclusion of a thief specialty class renders other classes obsolete in the performance of such duties and is the start of the path down the dark side toward modern style play where die rolls rather than player skill determine the outcome of all events.

I've been on the fence about thieves for a while now.  I've been long considering stripping unnecessary character classes out of my C&C game and now that I'm switching to S&W, which comes 'pre-stripped,' the question is what classes to add back in.  I've already green-lighted the monk for inclusion - I simply love the class and its abilities are not just minor elaborations of an existing basic class - a necessary criterion for inclusion.  Thieves, though, I could go either way with.  On the one hand I have a certain nostalgic fondness for them; they've been part of D&D since the Greyhawk Supplement, and one of my first characters was a thief.  On the other hand, the anti-thief camp makes a compelling case that I find hard to argue against.

I was pretty much decided against thieves until I recently read this post by James Maliszewski on Grognaridia.  James's argument is that the thief is a profession, not an archetype, and that 'thief abilities' used to be something that any class could attempt.  The thing that struck me about this argument is that it could equally justify the removal of the fighter class.  After all, fighting is something that every class can do; fighters just do it better.  By the same token, attempting thief abilities should be something that every class should be able to attempt, but thieves are really good at it, just as fighters are really good at combat.

Its easy to see why thieves could be perceived of as stepping on the toes of other classes because in traditional versions of D&D (OD&D, AD&D, Basic D&D) only the thief had a game mechanic to allow them to attempt thief abilities like hiding in shadows, moving silently, picking pockets, etc., expressed as a percentage chance to succeed (and a pretty darned low chance at the lower levels, at that).  Given the old-style resolution of thief abilities, it is no wonder that the thief emasculated other characters in a way that fighters didn't.  Non-thief characters were no longer able to even attempt to perform thief abilities.

Having played Castles & Crusades for several years now, I tend to think in terms of its SIEGE mechanic, which allows any character to attempt just about anything, while protecting niches by ensuring that specialists 'do their thing' better than anyone else.  For this reason, I didn't immediately grasp the threat that thieves posed to other classes because, in C&C other classes can still attempt thief abilities - just not as well, just as other classes can use weapons, but not as well as fighters

For those not familiar with C&C's SIEGE mechanic, tasks are resolved by making an ability check against a target number.  The target number varies, depending on whether the attribute is a prime or non-prime attribute for the character.  In addition to the obvious class-based prime attributes (i.e. Strength for fighters, Intelligence for wizards, etc.) players may customize their characters by selecting one or more additional prime attributes of their choice.  All attribute checks for prime attributes are against a target number of 12, whereas checks for non-prime attributes are against a target number of 18.  Thus anyone can attempt anything, but whether they are good at it depends on how they've customized their character by choice of primes.  For example a fighter who has dexterity as a prime and wishes to sneak past a guard just has to roll a d20 plus his dexterity modifier and beat a target of 12 plus the victim's hit dice. 

So where do thieves fit in?  Characters attempting something that is their class or racial ability also add their level to the roll, but characters attempting non-class abilities do not.  Thus, say you have a 5th level wizard who grew up as an orphan on the mean streets before being adopted by his mentor.  If he has a dexterity prime and wishes to pick the pocket of a 1st level npc would need to roll 1d20 plus dex modifier and beat 12 + 1 = 13 to succeed.  The same wizard without a dex prime would have to roll 18 + 1 = 19 to succeed.  A 5th level thief picking the same pocket would need to roll 1d20 + dex mod + 5 against a target of 12 + 1 = 13, so obviously he is going to be much better than even the sneaky wizard.

So, I think I will be including the thief class in my S&W game, but I will also be incorporating the SIEGE mechanic from C&C as the most elegant means of letting characters attempt anything while ensuring that they don't overshadow the specialists.