Multiverse explanations for fine-tuning

Many of the physical parameters of the observed part of the Universe, whether constants of nature or cosmological boundary conditions, seem fine-tuned for life and us [1—4]. There are three common explanations for this. One is that there is a ‘Fine-Tuner’ who providentially selected the physical parameters so that we can be here. Another is that it is just a coincidence that the parameters turned out to have the right values for us to be here. A third is that the observed Universe is only a small part of a much vaster Universe or multiverse or megaverse or holocosm (my own neologism for the whole), and that the physical parameters are not the same everywhere but take values permitting us in our part.

These three explanations are not necessarily mutually exclusive. For example, combining a Fine-Tuner with coincidence but without a multiverse, perhaps the Universe was providentially created by a God who had a preference for a particularly elegant single universe which only coincidentally gave values for the physical parameters that allowed us to exist. Or, for a Fine-Tuner with a multiverse but without coincidences, perhaps God providentially created a multiverse for the purpose of definitely creating us somewhere within it. Or, for coincidence and a multiverse without a Fine-Tuner, if the Universe were not providentially created, it might be a multiverse that has some parts suitable for us just coincidentally.