PP111 Lecture 10 Notes
Certainty and Doubt
• David Hume:
o “All our simple ideas in their first appearance are derived from simple
What can we know on the Basis of Experience Alone?
• We can know what experiences (‘impressions’) we are currently having;
• We can know (via memory) some experiences that we have previously had.
• Hume’s question: Can we know anything beyond this?
o Can I know… that the sun will rise tomorrow?
o …that the smoke on the horizon is a sign of fire?
• Knowing these things require us to make inferences from:
i. What we now experience and what we remember having experiences in
ii. What will happen in the future
Hume’s Skepticism (About inferences That go Beyond Present Experience)
1. All out knowledge of what will happen depends on our knowing that the
future will resemble the past. [ The Uniformity of Nature’]
2. BUT: We cannot know that the future will resemble the past
3. So, we have no knowledge of what will happen no knowledge of matters
beyond our present experience and memory
Can experience justify a belief that the future will resemble the past?
1. In the past, the future has always been like the past. So, it is reasonable to assume
2. In the future, the future will be like the past
• Problem: (2) follows from (1) only if we assume that in the future things will
behave as they have in the past.
o But that is just what we are trying to prove
o Fallacy: CIRCULAR REASONING (reaso