Defending the 2nd Premise of the Kalam Cosmological Argument
Succinctly, the second premise of the Kalam Cosmological Argument (hereafter KCA), can be stated as such: “the universe began to exist.” For centuries this statement was considered false due to a reliance on Aristotelian metaphysics, since “for Aristotle the world is eternal, [therefore] the question is not whether there is a temporally first cause, but rather a highest cause….”1A.G. Vos, “Aristotle” in New Dictionary of Christian Apologetics, edited by Walter Campbell Campbell-Jack and Gavin McGrath, Ivp Reference Collection (Leicester, England: Inter-Varsity Press, 2006), 87. However, recent philosophical work (spearheaded by scholars like William Lane Craig) and contemporary scientific discoveries now provide strong evidence to support the position that indeed the universe has a finite past. Here is one strong philosophical argument and two well-established scientific positions that demonstrate the soundness of this premise.
The Impossibility of an Actual Past Infinite
There are two main problems with positing an actually infinite past (or an infinite number of past causal events). First, is the problem of “traversing the infinite,” for if there were an actual infinite number of past events, that would seem to imply that an infinite number of past events would have to had already occurred in order for the present moment to have come into existence. However, since it is logically impossible to complete (by successive counting, for example) an actually infinite set of anything, then it raises the question as to how the present moment has actually obtained. However, if you have an actual beginning point (a temporal beginning, so to say), then you do not have to traverse an infinite set of anything, rather you can simply understand the present moment as one part of an increasingly large set of moments.
Second, there are the mathematical paradoxes that arise if actual infinities are posited as real things. For example, subtracting all the odd numbered legos from an infinite collection of legos, still results in an infinite number of legos, whereas subtracting all the legos numbered 3 or higher results in having only two legos remaining (even though you have subtracted the same infinite number of them)! These paradoxes demonstrate that the existence of an actual infinite set of anything (legos, temporal events, or otherwise) is highly improbable.
The Ever-Expanding Universe
Although there are alternative hypotheses to the standard cosmological model of the expanding universe (“The Big Bang”), most of them have been shown to be mathematically and empirically inferior to The Big Bang model.2William Lane Craig, “Cosmological Argument” in New Dictionary of Christian Apologetics, 181. If the Big Bang model, which suggests a continually expanding universe, stands as the most plausible empirical theory we have of the nature of the universe, then we have very good reason to believe that space and time came into existence at a finite point in the past. Of course, if we argue that time itself came into existence, it is true we cannot talk about a time before time. However, we can assume a metaphysical point or a logically “prior” edge to our current space-time continuum (itself measured by change within the universe), where the universe and all that is in it did not in fact exist. On the other side of this edge then, is something other than, or outside of, space and time. This entity would therefore not be subject to temporality as we understand it, or even spatial extension.
The Present “Presence” of Usable Energy
Finally, the finitude of the universe is supported by the 2nd Law of Thermodynamics. This law suggests that the total amount of usable energy in any given “closed” system will always decrease over time. This is also known as entropy, or the idea that things in a system always move from a state of higher order to one of disorder. Our universe is like this (assuming it is indeed a closed system). Thus, if an infinite series of past events had already occurred, we would expect all of the usable energy in the universe to have expired an infinite amount of time ago and we would not be here to formulate arguments about its finitude since this heat death would have occurred a long, very long, time ago. Of course, at this juncture, one could contend that the universe is not a closed system and that it continues to receive usable energy from some source outside itself. However, this inevitably raises the question of what that source might be- a source that would exist external to our space-time continuum and also supply our universe with an abundance of usable energy, would have to be considered. However, if the universe is indeed a closed system, as naturalism must assume, and if it still possesses usable energy, which it obviously does, then it cannot be infinitely old.
Therefore, we have shown through one philosophically sound argument and two scientifically established theories that premise two of the KCA is indeed sound and that the universe has most likely had an actual beginning in the past.