I have come across claims that first causes are not needed we can always have an infinite regress. Is this good logic is what I'm wondering. If the universe has an beginning should we believe that there is an infinite regress of causes (making any inquiry about the qualities of the cause impossible) OR would it be better logic to posit a first cause and take further inquiries from there?

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    "I have come across claims…": Could you reference or link to them? that would make it easier to follow the argument.
    – DBK
    Jun 4, 2014 at 10:35
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    Sorry DBK it is just things I hear when people sometimes talk about First Causes and the like.
    – Neil Meyer
    Jun 4, 2014 at 11:31
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    This seems to ask "Is infinite regress of logical causation possible?", but in different words. Jun 5, 2014 at 8:31

2 Answers 2


It isn't necessarily invalid to accept infinite regresses. Rejecting them was a classical and medieval requirement for two reasons:

  1. An infinite regress defies the chain of causation it is meant to explain. In other words, if you define causation as A --> B, then for any B, you need an A. An infinite regress would mean never arriving at the A at some point but claiming that what we're talking about is still causation.

  2. Medieval and ancient thought rejected the possibility of an actual infinite. A infinite regress requires an actual infinite. I'm sure shane could give a more thorough answer because this is closer to his speciality, but I'll just [cite wikipedia1] to show you the list of authorities on that.

But many modern views believe actual infinities are possible, solving problem 2, and many believe causality is in the mind -- semi-solving problem 1. In medieval logic, arriving at an actual infinite is the same as arriving at a contradiction -- a sign that something has gone wrong.


Aristotle claimed that actual infinites aren't possible but potential infinities are possible.

In mathematics it appears that completed infinities are possible, for example omega, the completion of the natural numbers; but since you can always go beyond a completed infinity, Aristotles claim when properly interpreted in this domain still holds.

Now we can conceive a chain of causation ...->a2->a1->a0 that extends infinitely in the past; now what holds for succession above, holds also for predeccesors; so one can complete this; but again by the same argument above one can precede again; thus, in this sense, there can not be an infinite regression - there is either first cause, or a first cause in potentia; and by completion we arrive at a first cause again.

The moral of this story is that infinite regression doesn't neccessarily exclude a first cause.

  • "since you can always go beyond a completed infinity, Aristotles claim when properly interpreted in this domain still holds" — is that to say that there are no completed (final; show's over folks, nothing more to see here) infinities? Is the objection to actual infinity the idea of "having made it finally", or "having made it so far from where we started"? I've always supposed that it was the latter... Jun 6, 2014 at 9:41
  • @NieldeBeaudrap: Perhaps it was a little presumptous or improper of me to interpret Aristotle 'properly' when I can't read ancient attic Greek... Jun 6, 2014 at 10:00

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