Use of Proficiencies by Nonproficient Characters (POSP)

In general, characters will not be able to perform a task unless they have some level of proficiency in it. However, the DM can allow nonproficient adventurers to attempt proficiency tasks, under a few circumstances. In general, the tasks performed must be very simple, and the character will not be able to perform them very well. Tasks that nonproficient characters attempt would generally fall into the automatic success category if they were attempted by a proficient character. A nonproficient character must roll a successful check using the proficiency's initial success rating, modified by the character's relevant ability. If a trait is relevant to the use of the proficiency (see proficiency descriptions), a nonproficient character with that trait can claim this modifier when attempting a check.
Several considerations might allow these types of checks:
Life or Death: A non swimmer who falls in the water might be allowed to make a swimming proficiency check. Success means the character is able to stay afloat, perhaps moving slowly toward shore. Note that this would be an automatic success for any character with the swimming proficiency. If modifiers exist that would require a proficient character to check (the PC is encumbered, or the water is very rough) then the nonproficient character will certainly fail.
All the Time in the World: A character who does not have the agriculture proficiency, but is willing to spend two weeks planting a small plot of land, should be allowed to make a proficiency check. Success means some kind of useful crop.
Excellent Instruction: If the blacksmith's arm is broken, but he can sit next to the forge and describe to the novice every step of the procedure, the nonproficient character should be allowed a proficiency check to create a simple object such as a horseshoe or a nail. Anything that would require the blacksmith to make a proficiency check, however, would be beyond the skills of the nonproficient character.