I've been growing increasingly critical of attributes that measure properties that are so dependent on a player's abilities that their separate measurement for characters does nothing but add conceptual confusion about the site of agency. Intelligence, Wisdom and Charisma of the six classic attributes are the particular ones I am moving closer and closer to simply replacing.
Intelligence: The problem is two-fold: Simply that a dumb person cannot roleplay a smart one without constant fudging, assistance, and interference by others; and the concept of g which underpins a unitary intelligence attribute is psychometrically dubious and conceptually overladen. When I meet smart people in ordinary life, I find that their minds produce thoughts with distinct, often recognisable characteristics that are unique to them. By contrast, when a character is "smart by committee" in a game, the presentation of their ideas is vague, and imprecise, and the chain of reasoning that led them there cannot be reproduced.
Wisdom: This attribute is a muddle of different qualities, even within its two larger categories of "Perceptiveness" and "Insightfulness". I have never managed to find two people who agree on what exactly a "high Wisdom" character is like once you get beyond vacuous and banal generalities. The character with the highest Wisdom I have ever played (18) was a psychopath who had driven himself to prodigal levels of skill from an early age, and whose basic attitude towards others was that they were mildly dangerous pets.
Charisma: Another conceptual muddle, and another one where players skills overwhelm character ones, unless one takes seriously the advice to let dice-rolling overwhelm excellent roleplaying and the formulation of reasonable, compelling arguments or plots. Basically, either you make this attribute irrelevant, or you make roleplaying irrelevant, or else one becomes the back-up for when the other fails.
I think that by choosing more constrained and reasonable elements from each of these conceptual muddles, we can relegate the rest to the realm of roleplaying and player ability, which are far easier to talk meaningfully about and to resolve problems with than continuously trying to resolve the unsolvable puzzle of how a player's charisma should interact with a character's charisma.
In place of these three attributes, I propose:
Intelligence could be replaced with an attribute called either "Attentiveness", "Acuity" or "Reactivity". Acuity would measure a character's conscientiousness, attention to detail, visual acuity and ability to integrate and adapt to changes in the environment. Specifically, it would influence initiative rolls and saving throws, cover what is now lumped together under "perception" tests of various sorts, and assist in finding traps and clues and such.
Wisdom could be replaced with "Calmness", "Focus" or "Repose". Focus would measure a character's ability to remain calm in stressful or confusing situations, to concentrate on a problem or object of reflection, and to avoid being distracted from their goals. It would be the spellcasting attribute used by wizards. It would help with certain kinds of saving throws, as well as resisting temptation, and overcoming certain types of fatigue.
Charisma could be replaced with "Grace", "Luck" or "Holiness". Grace represents a person's connection to the greater magical forces in the universe, especially but not limited to the gods (if any), demons, extra-dimensional tulpas, whatever. It serves as a luck attribute, as well as being the key casting attribute for clerics and other divine casters. It should aid saving throws to resist magic effects, and general misfortune.
Each one of these is conceptually narrower than the attribute it replaces, but I think the added coherence is a benefit here. As well, these are all areas in which the character's abilities can be clearly distinguished from the player's. Since players primarily deal with verbal descriptions of what their characters are seeing, acuity represents a characteristic that the player cannot truly exercise. Focus pushes roleplaying by preventing characters from asserting that their characters are psychopathically and implausibly calm in situations that there is no reason to believe the characters would be as blase about as the players are. Grace represents the luck of the character, something player ability has no real effect on unless that ability is cheating on dice rolls.
I have not tested these out, but I think I shall in my next Swords and Wizardry Complete campaign, whenever that will be. Anyhow, I'm curious for people's comments and opinions on these changes.