Phil 105: Science and Philosophy - Fall 2004 Lectures

!You will be sorely disappointed if you think that these are a substitute for attending class!

Topic Four: Time

1. A Moving Present?

• Focus on what is at stake:
• (a) Proposal: there must be a moving present, …
  
• (b) … because only a moving present can explain why space and time appear different to us.
  
• (c) Further, this moving present is not a feature of the block, in which time is very much like space.

• Question: what could this moving present be like? Could anything really satisfy (a) and (b)?

• First attempt: why isn't the analogy to slices lighting up in sequence over time immediately useful?
• We'll see if there's some sense to be made of it anyway.
  

2. McTaggart

•  Nowist: Suppose that being the (moving) present were a property of instants (purely spatial slices of the block) – so it was like being illuminated.
  
• But every slice in the block must have this property – why?
• Why does that conflict with (a) – with the motion of the present?
  
• Why does it seem logically impossible?
  

3. Different Properties of Presentness

• Nowist: Suppose that being the (moving) present were a different property at different instants – so it was like each slice being illuminated a different colour.
• Then the present moves in the sense that each instant is the present in a different way – avoiding McTaggart.
  
• But what are these different properties?
  
• (i) The relative present: e.g., 'being the present at 12am', 'being the present at 1am', &c – how should understand the times?
  
• Possibility 1: The slices already are times in the block – e.g., 12am and 1am &c are already in the block – but if we take the properties to be 'being the present at the 12am slice of the block', 'being the present at the 1am slice of the block', &c then we don't have anything that isn't already in the block – contrary to (c).
  
• Possibility 2: External clock – but then we have two times, in the block and out, which is absurd (I'd say).
  
• (ii) Some new property:
• The values of some physical property of the world – analogous to the temperature increasing? But such a  physical property is already in the block, contrary to (c) – though it may be a property we were otherwise unaware of.

4. Present Existence

• Nowist: Suppose the present moves – time passes – in the sense that at each moment only that moment exists – the past and future do not.
  

• In the block we can distinguish two senses of 'existence':
• Being at some time or other in the block – absolute existence.
  
• Being at some specific time – e.g., 'now' – in the block – relative existence.

• By (c) the nowists' sense of existing now can't just be existing relative to now – being around now. Why?
  

• But somthing exists now in the nowists' sense if and only if it exists relative to now – can the nowists' sense of existence explain our experiences in a way relative existence (and the regular properties) don't? (b) is not satisfied.