How do we really know that we (and everything else) wasn't created an instant ago, and everything we remember from the past is an illusion, a figment of our imagination to comfort ourselves from seeing and remembering the truth that all is not as it seems?

  • Because we assume otherwise, and it works out.
    – Conifold
    Commented Sep 16, 2016 at 18:29

1 Answer 1


It depends what you mean by "instant" and "past". Both these terms derive from measurements that are taken from the reality we experience. There is no such thing as an "age" that something might "really" be other than we experience it because the entire concept of age is derived from measurements of the universe as we experience it. If we are to doubt the truth of that experience then we must apply the same doubt to the concept of time itself. We have no justification for believing one but doubting the other.

  • So it would be a doubt about the nature of reality itself? Commented Sep 17, 2016 at 18:16
  • 1
    Yes, questioning reality itself as we sense it is perfectly rational as it is clear from both scientific instruments and even other animals that our senses are limited, but reality has a great number of components and so to question each one in turn whilst presuming the others to be true would be an impossible task to complete and so not a particularly advisable one to start.
    – user22791
    Commented Sep 18, 2016 at 6:16

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