We provide reasons in order to justify the performance of a certain action or the acquisition of certain beliefs. Tom being your friend is a good reason for you to attend his birthday party. The sky being cloudy in the morning is a good reason for me to believe that it may rain in the afternoon.

Reasons have strengths or weights. The weather forecasting rain this afternoon is a stronger reason for my belief that it will rain than seeing the sky cloudy. In fact, reasons can out-weight other reasons or even cancel them by being opposites. Your need to take care of your sick daughter is a reason that out-weights the reason to attend your friend’s party.

What principles relate the weights and opposition of reasons to our performing certain actions or acquiring certain beliefs? Is there a logic behind them? I am currently working on this topic with Alessandra Marra (MCMP), based on previous work by Hannes Leitgeb (MCMP).