What are ability scores used for in Dungeons and Dragons?

Question

In Dungeons and Dragons 3rd Edition, a character's ability score is never rarely used. We only use it at character creation, to calculate the ability modifier. So, why bother having BOTH the ability score and the ability modifier? I feel the game would be easier to learn if we only had the modifiers in the character sheet (and called that the score). I know that some editions use the Constitution score, but that's an exception that feels tacked on.

I assume the designers are much more talented and wiser than me. So, why do we need separate ability scores and ability modifiers?

Answer 1

Your starting assertion is wrong. Ability scores actually are used for a number of things in Third Edition that are not entirely trivial to replace with modifiers. In very rough order of importance:

• Ability damage from poisons and such-like would be twice as dangerous if it simply attacked modifiers at the same rate, and given the usually small dice involved already, that would make it difficult to arrange reasonable spreads even by halving — what does filth fever's 1d3 Dex and Con turn into?
• Odd scores are necessary for casting spells of odd-numbered levels — using modifiers means spells become accessible either two levels at a time, or only at twice the ability they previously were, which starts to affect NPCs significantly (requiring a score of 28/modifier of +9 to cast 9ths, for example) as well as partial casters (requiring Rangers to have a Wis score of 18/modifier of +4 by 14th level to cast 4ths)
• Gaining an ability modifier bonus only every eight levels would be rather irritating (with a mere two and a half before epic, which means only two choices); gaining every six levels or some such thing would require a bit of balance re-checking, and still more so if you kept it at every four levels
• Carrying capacity is keyed directly off of Str score, not modifier, so switching would lose a bit of resolution
• In Pathfinder, as you note, Con is used for the range of HP from dying to dead; doubling the modifier instead and adding ten is slightly less elegant and has a bit less resolution
• There are some miscellaneous places, like feat prerequisites, that technically use odd ability scores even though modifiers would be scarcely different

In essence, then, you're trying to remove backwards-compatible rules that were put there to handle a multitude of special cases that some games really rely on — your group may not use disease or poison or carrying capacity or minimum spell level scores or care about exact prerequisites or the timing of ability bumps, but the system as a whole is designed with those in mind. And dropping that would impact things that some gamers really do care about.