Monday
Monday's unpredictability lies not in whether it will arrive - this is grimly certain - but in the specific torments it will deliver. Will it be the overflowing inbox? The emergency meeting? The discovery that last week's problems have somehow multiplied over the weekend? Monday possesses what chaos theorists term 'bounded unpredictability': the framework is fixed, but the contents are endlessly variable. Each Monday arrives wearing a different mask of misery. One never knows quite which fresh hell awaits, only that hell most certainly awaits.
Bear
The bear is a genuinely unpredictable entity. Even experts cannot reliably predict bear behaviour in any given encounter. A bear might charge, might bluff, might ignore you entirely, might develop an inexplicable fixation on your rucksack. This unpredictability is heightened by the bear's intelligence: unlike Monday, the bear actively makes decisions. It assesses, calculates, responds. A bear encounter is a dynamic negotiation between two sentient parties. Monday, by contrast, is indifferent to negotiation. The bear at least acknowledges your existence as a factor in its decision-making process.