the whys and (the) wherefores

the reasons for something.

I know very little about the whys and the wherefores of the situation.

• on the lam
• on the level
• on the line
• on the loose
• on the margins of
• on the margins of something
• on the market
• on the mend
• on the merits
• on the money
• on the move
• on the nail
• on the never-never
• on the nod
• on the nose
• on the off-chance
• on the off chance
• on the one hand
• on the one hand...on the other hand
• on the other
• on the other hand
• on the part of
• on the part of someone
• on the prowl
• on the quiet