Amongst philosophers, the theory of knowledge is a contentious one. Also, as pointed out by Hume, there are circularity issues with the type of inductive reasoning used within science. Consequently, no explanation of the world around us can ever be claimed with absolute certainty. One can only reach provisional conclusions. In a real-world scenario in which we have many possible hypotheses that explain a phenomenon (possibly including supernatural ones), rationality dictates that we should provisionally accept the most reasonable hypothesis on offer.
When it comes to fathoming the universe, what counts is finding the most plausible hypotheses by means of comparing them with observation. In order to move beyond the realm of pure metaphysics, one must endeavour to compare one’s chosen hypothesis with reality, to assess its fit with the evidence. With no requirement to compare with reality, one can concoct ever-increasingly complex worldviews, without any way to know if they are true or not. Logical consistency alone as a criterion will only get you so far, as an infinity of logically consistent hypotheses can be put forward to explain some phenomenon or other. We have to compare our favoured hypothesis with reality. As Hume said - even a rational man with no experience “could not have inferred from the fluidity and transparency of water that it would suffocate him, or from the light and warmth of fire that it would consume him.”
In such a scenario, I assert that we should resort to an argument to the best explanation. In general, the more one explanation exceeds all others on each of the following criteria, the more confident we can be that it is true -
• Explanatory scope
• Explanatory power
• Evidential fit
Based upon this, what conclusions can we draw if we compare the God hypothesis with a generic scientific multiverse theory?
Firstly, we should note that the most parsimonious hypothesis is the one that explains the observations whilst introducing the fewest ad-hoc assumptions. So, the multiverse concept is plausible as it is entirely consistent with known physical laws; is parsimonious, as it actually introduces none or very few ad-hoc assumptions (depending upon which version you favour); and has a great deal of explanatory power and scope, as it explains why we see the particular universe that we inhabit, rather than some other possibility (and so, in one fell swoop, rebutting the cosmological fine-tuning argument). In fact, it is less parsimonious to conjecture a single universe rather than an infinity, as this would require the positing of some ad-hoc rule explaining why only one of an infinity of possibilities actually exists.By contrast, the god hypothesis suffers from a number of problems –
• It is not plausible, as it requires the positing of a supernatural universe-creating entity – when we have no reliable evidence that anything supernatural exists at all. The only methods that have so far been shown to work consistently are empirical ones, and they have thus far only discovered natural things and causes.
• It has no power or scope, as it does not explain why we see the specific universe that we do. Why would God choose to create a universe that is so vast and is almost entirely a radiation-filled vacuum? Why would God choose to create a universe that takes billions of years to evolve? Why would God choose to create a dizzying array of fundamental particles? Why would God choose to create a universe at all? These can only be answered by introducing more ad-hoc assumptions.
• It is not parsimonious, as numerous ad-hoc assumptions are required in order to explain the existence and properties of God, and of the universe created by it. At first sight, it may seem to be a seductively simple explanation. However, this simplicity is shown to be illusory once one analyses the implications entailed by this explanation.
• Further, it must be less parsimonious to invoke an eternal and uncreated supernatural creator of the universe, than to suppose an eternal, uncreated and infinite universe that is consistent with known physical laws. Purely by logic alone, if we can suppose that God can be eternal and uncreated, we can also suppose the same of the universe, and dispense with God altogether. Further, the concept of an eternal and uncreated universe is explained by a variety of scientific hypotheses that are consistent with known physical laws, whereas the concept of a supernatural entity is not consistent with naturalism.
• If we were to presume the existence of a supernatural creator, then what explains why this creator exists at all? Why not just no God and no universe? If we are allowed to posit an eternal creator that has no explanation, then why can we not posit an eternal universe that has no explanation? This is more parsimonious as it does not require the introduction of any supernatural entity.
• If we further suppose characteristics of God that are part of conventional Christian doctrine, then we run up against other notorious problems - such as the problem of evil, and the problem of divine hiddenness – that theology has no convincing answers to.
So, in summary, I would contend that the scientific multiverse hypothesis offers a better explanation of the existence of our universe than does the God hypothesis. In general, I would contend that the worldview that is the argument to the best explanation of the world we see around us is metaphysical naturalism. That does not mean that metaphysical naturalism is necessarily true, but rather that it is currently the best explanation on offer. Thus, I contend that it should be provisionally accepted. It is certainly a far better explanation than any competing theistic worldview.
If you would like to read more about this, I can highly recommend Richard Carrier’s book ‘Sense and Goodness Without God – a Defense of Metaphysical Naturalism’