Last night I was wandering, mostly aimless, around the vast dungeon of old school blog posts, and happened to click the "Intelligence" tag at The Tao of D&D. While reading those posts, I had a flash of inspiration, which is only peripherally related to one strand of thought within the posts, but you should read them anyway if you haven't already, because they're excellent. Whether it was a good and useful inspiration or not you can judge for yourself...
First, however, I need to elaborate a bit on my ideas about Intelligence and Wisdom and what they represent.
Wisdom, to me, represents intuition, inspiration, the unconscious or subconscious mind. It's constantly processing all the inputs from your senses, comparing and testing them against your mental database of experiences, and yielding up insights, epiphanies, premonitions, anticipation of impending events, and such. It operates as a sort of mental speed dial or hot key system, prompting action in a tiny fraction of the time it would take your conscious mind to analyze a situation and reach a conclusion, even if you were consciously paying attention to it. While it's fast and always operating even when your conscious mind wanders, it isn't infallible. If the stock of data and stored knowledge it operates on is flawed, it's garbage in, garbage out, and your intuitive reaction will be either totally counterproductive or not as effective as it could be.
Intelligence is the ability to consciously analyze and integrate information. It's much slower than Wisdom, but under conscious control. When you encounter something new and outside your previous experience, it's your Intelligence that breaks it down, evaluates it, and determines how it meshes with your existing store of knowledge. If necessary, it can re-evaluate your old knowledge in light of new information, and is thus the error checking system for the data that your Wisdom relies upon. Your subconscious mind will stubbornly cling to the old data, so it takes some effort to successfully over-write it with new knowledge - in other words, conscious repetition and practice.
All of this, to me, suggests something profound for the gaining of experience in a class and level based game system. It's your Intelligence that is responsible for analyzing new information and integrating it into your stock of knowledge. This is true whether that information has to do with blacksmithing, needlepoint, magic, or combat maneuvers. In other words, should it not be Intelligence, rather than the class's prime requisite ability, that is solely responsible for variations in the rate of class progress and determines experience point bonuses and penalties?
It isn't as ridiculous as it might seem at first. A fighter's Strength is useful to his profession immediately, in the here-and-now. He swings, he gets an adjustment to hit and to damage. But how in the world does being strong help him learn his trade faster? All else being equal, including level of experience, a 16 Strength, 9 Intelligence fighter is going to be more effective than a 9 Strength, 16 Intelligence fighter. The difference comes over time, as the smart fighter learns the tricks of swordplay more rapidly than his less smart counterpart. He'll never have that valuable bonus to damage, but as time goes by, he'll gain an advantage to his attack rolls and his ability to avoid bodily injury as expressed in hit points over less intelligent fighters who have done a similar amount of adventuring. That's what being smart does for him.
I know this bucks one of the oldest traditions of D&D, dating all the way back to the original. Back then, XP bonuses were the primary function of ability scores. The game was much stingier with ability score-based bonuses to combat rolls, saving throws, and such. In the editions that followed, "old school" though they may be in relation to modern editions, ability bonuses were expanded, and applied to more situations. Strength has a noticeable impact on melee combat. Dexterity affects missile combat, and Armor Class, one of the most important stats in the game. Constitution is an important determinant of hit points, which in turn determine survivability. Charisma, properly applied, is a lot more influential in the game than is commonly understood. That leaves Wisdom, by the book affecting one sub-category of saving throws, and Intelligence, good for literacy and languages, largely out in the cold.
In my post on playing the fool, I suggested that Wisdom should apply to most, if not all, saving throws. I posited a few possibilities for making the language bonuses from Intelligence more meaningful, but most of my other ideas for using the ability were in role playing, not game mechanics, which still left a disparity. Now, I'm hopeful, the gap has been filled at last, with every ability score being applicable to every character class in a quantifiable way. I'm going to be putting the current campaign on hold for a while soon in order to try some of my house rules and tweaks, and this one will certainly be getting a test drive.