If designing a system from scratch I personally would want to get rid of ability scores.
Personally I like ability scores. We are more than the sum of our learned skills. We are also talents, inherent aptitudes tending to be good a certain skills. I feel the ability tradition is a reasonable way to represent the concept of talent.
In D&D 5e, the benefit from talent (ability score) and the benefit from learning (skill proficiency) are roughly equal contributions. The maximum benefit from talent is +5 and maximum from learning is +6 (until a hypothetical epic tier).
Even the way 5e allows the character to improve the ability score feels verisimilitudinous. I feel, learning does improve the general aptitude, allowing more competence in other skills. Like the football player who studies ballet to improve his football performance, and so on.
However, if I wanted to keep ability scores then I would do something like this: ...
Intelligence:
Observation, Deduction
Charisma:
Influence, Detect Influence
These mental abilities in the quote seem to resemble:
• Intelligence: Perception, Investigation
• Charisma: Persuasion, Insight/Empathy
(Note, I prefer to call ‘Insight’, the ‘Empathy’ skill. I feel the term is more specific to social skills, and helps distinguishes its use from, say, ‘insight into what a mathematical integral represents’.)
Thinking about these, I contemplate the following.
• Intelligence: Perception, Investigation-Deception, Lore, Tools.
I suppose Perception and Investigation are separable. Perception is the ability to detect a faintly visible phenomenon, while Investigation is the ability to interpret and extrapolate what this faint evidence represents. In the extreme case, an animal might have a high Perception, yet remain clueless and unable to recognize, understand, or respond meaningfully.
On the other hand, the power to interpret clues, allows the perceiver to perceive much more. Something like Sherlock Holmes ‘notices’ more evidence (via Perception) because of the analytical skills (via Investigation). In this sense, especially for a human, it is impossible to separate Perception from Investigation.
On balance, it is reasonable to link both Perception and Investigation, and here the ‘Intelligence’ ability score represents this inherent link between Perception and Investigation.
Investigation also includes ‘intuition’, a gut feeling or inspired concept for how evidence pieces together.
I feel strongly that Deception belongs to Intelligence. The ability to forge a document, replicate some artifact, or come with a convincing lie that can survive the scrutiny of experts, requires extreme knowledgeability. Essentially, the Investigation skill that perceives a reality, is identical to Deception that constructs a reality. Moreover, Deception is really about the ability to create a simulation. The skill forms any kind of a virtual reality, and is not necessarily for the purpose of deception. It might be for an authentic vivid experience, such as painting a realistic lifelike portrait, or crafting an authentic replica of a destroyed artifact. I view Illusion magic as relating strictly to Intelligence and the ability to reconstruct a virtual reality that is convincing. The purpose of an illusion might be for improvement, without the intent of deception. One might use the Deception skill to forge a replica of a document to deceive an observer, or one could use the same skill to accurately recreate a page from a spellbook. I would prefer to call the Deception skill ‘Simulation’, in the sense of being able to replicate some phenomenon with precision. But in any case, the Investigation skill is moreorless the same thing as the Deception skill. The same Investigation that can discern the implications of the evidence and reconstruct the reality in ones mind, can also be used deceptively to convincingly fabricate a reality. Hence, Investigation-Deception.
I would also add ‘Lore’ to the Intelligence category, essentially representing memory, experiential knowledge, and formal and informal education. Lore subdivides into specific skill sets relating to the overall topic.
It turns out, D&D 5e evolved to feature the best ‘crafting’ skill of any edition of D&D. The catch is, 5e makes ‘crafting rules’ part of proficiency with tools. The tool set determines what kind of things a character can craft.
Ultimately, Intelligence represents an aptitude for observational and exploratory skills, including technological discovery and use.
• Charisma: Charm, Frighten, Empathy, Willpower
For me, Charisma is a catchall term for social skills, and is moreorless synonymous with ‘emotional intelligence’. The ability to read people and influence people are two aspects of Charisma.
Personally, I like the distinction between positive reinforcement (appealing to desires) versus negative reinforcement (appealing to fears). Charm/Persuasion and Frighten/Intimidation. Carrot and Stick. This Frighten would be identical to Intimidate, but one can more clearly ‘intimidate’ someone by reminding someone of undesirable consequence − without actually making any threat personally. Heh, such as saying, ‘If you do that, your daughter might end up dating such-and-such a person.’ There is no threat made, just a playing on fears. So ‘frighten’ is a clearer term, for any kind of negative reinforcement. When extreme, I am comfortable with these causing the ‘charmed condition’ and the ‘frightened condition’, respectively.
I view artistic beauty and esthetics as a Charm/Persuasion check. Any artistic creation or performance requires two separate skill checks. One is for the technical mastery (for examples, Intelligence Investigation-Reconstruction for a lifelike portrait or Agility Athletics for an impressive dance), the other is for its esthetic appeal (Charisma Charm).
Willpower is also a salient aspect of Charisma, in the sense of confidence, resolve, persistence, and an individuating autonomy that can resist social pressure. Hope too is an aspect of this Willpower. Willpower can be passive in the sense of resisting someone else’s Persuasion. Persuasion itself covers the more active use. But Willpower can also be active, in the sense of Maintaining Focus, Concentration, Exerting Psionic Force, or so on. Magic done by ‘force of personality’ essentially utilize Willpower.
For the sake of a clean line, all ‘Lore’ relating to social skills utilizes the Charisma ability, no matter how technical that psychological jargon might be. In any case, the only persons who can understand the jargon accurately are the ones with the emotional intelligence to inherently understand the emotional aspects that the jargon refers to.
Ultimately, Charisma represents social skills, including empathy and its ability to relate as a social creature, plus the ability to influence (via desire or fear), and the willpower to convey confidence. A leader needs all three aspects.
This post is already lengthy. I will think more about the physical ability, and post any thoughts on it later.
In sum:
• Intelligence: Perception, Investigation-Deception, Lore, Tools.
• Charisma: Charm, Frighten, Empathy, Willpower