Does time really exist? Philosophers give 3 main answers: time really passes, time is in the mind and passage is an illusion. AskPhilosophy presents 11 arguments, from Heraclitus of Ephesus to Arthur Prior, reconstructed step by step, logic-checked and verified word for word against their original texts.
The 3 possible answers
Each column is one way of answering the question: what it holds and the philosophers who defend it. Click a column to see only its arguments.
Time is real and flows: the present moves on, the past is no more.
Aristote, Isaac Newton, Henri Bergson, Arthur Prior…
Time is a way the mind grasps things, not a thing in the world.
Kant, Augustin
Past, present and future exist alike: the passing of time is an illusion.
Parménide, Kurt Gödel, J. M. E. McTaggart, Albert Einstein
The arguments
Click an argument to see it step by step, with the objections and replies.
Time really passes
Time is real and flows: the present moves on, the past is no more.
5 argumentsTime is the number of movement in respect of before and after
Without change we do not feel time; time is what we count in movement when we tell a before from an after.
There is an absolute time that flows by itself, and our clocks only measure it approximately
No motion measures time exactly, yet the duration of things stays the same: so there must be a true time behind our clocks.
Clock time is spatialised time; real time is lived duration
Clock time lines up moments like points in space; lived time is a flow of changes that melt into one another.
'Thank goodness that's over!': our relief shows that the present moves on
We are relieved that the exam is over now, not that it falls on some date: a date true at all times cannot express that.
You cannot step into the same river twice: change is the ground of things
A river's waters never stop changing, and so does everything: what lasts is an order that holds within change.
Time is in the mind
Time is a way the mind grasps things, not a thing in the world.
2 argumentsTime is the form of our inner sense: real for experience, nothing in itself
Time is not drawn from experience, it makes experience possible; so it must be a form of our mind, not a thing in itself.
Time exists only in the soul: the past is no more, the future is not yet
The past is no more, the future is not yet, the present has no extent; yet we measure time, so it must exist in the mind.
Passage is an illusion
Past, present and future exist alike: the passing of time is an illusion.
4 argumentsWhat is neither comes to be nor passes away: becoming is only a name
What is cannot come from what is not, nor go back to it: so there is no birth or ending, and becoming is only a name.
Rotating universes: if one can travel into the past, the passage of time is not objective
In worlds the laws of nature allow, one can return to one's own past: then nothing justifies believing in an objective lapse of time.
Time is unreal: the series of past, present and future contradicts itself
An event would be past, present and future at once, which is contradictory, and explaining it by time is circular.
There is no 'now' for the whole universe: past, present and future form a block
Events simultaneous for one observer are not for another: no single "now" holds for the whole universe.
Other philosophers' positions arrive as profiles are completed. No position is presented as the winner.