So You Rolled A 3: Intelligence

Dumb! Dumb! Dumb!  It's  easy to imagine a particularly dim fighting man, who is only good for sucking up hits and swinging a mighty battle axe. Decades of half-orcs and barbarians have been played like this and the trope has been screwed right into the ground, like some goofy Dwarf with a Scottish brogue. 

But remember in the old school, an Intelligence score of 3 is perfectly playable. Like we said with Strength, an Int of 3 doesn't necessarily mean someone is feeble-minded. It means instead that they might not be so clever, creative, or be passionate about learning. It might mean they are willfully ignorant of the world around them - incurious, as opposed to unobservant (that's covered by Wisdom). 

The most likely scenario is that the person is quite passionate about his field of expertise but you can't get him to think very deeply about anything he doesn't care about. Fighting Men are very smart about fighting; clerics are very smart about religion and monster hunting; and magic users are very smart about spells and magic items. 

Yes, even a Magic-User can have an Int of 3 in the old rules! In most rules sets, his XP will be penalized slightly, but he is perfectly able to cast spells and even able to learn new ones like his high-Int peers!

But what an INT 3 does NOT say is that you, the player, have to stop being clever.  You can use your player knowledge to solve problems and get by.  Don't even think you have to dumb yourself down because your man is dumb!