According to Wikipedia:
The soul, according to many religious and philosophical traditions, is a self-aware ethereal substance particular to a unique living being. In these traditions the soul is thought to incorporate the inner essence of each living being, and to be the true basis for sentience. In distinction to spirit which may or may not be eternal, souls are usually (but not always as explained below) considered to be immortal and to exist before their incarnation in flesh. (emphasis mine)
So, keeping with the canonical definitions of “sapience” and “sentience” (see my earlier post about this) the basic consensus of what makes a soul is sentience, not just life (which, of course, cuts the anti-choice movement’s arguments against abortion when they attempt to make the argument that life begins at conception). Even St. Augustine, in “On Exodus,” wrote that a human soul cannot exist within a body that hasn’t been completely formed.
One of the last things to fully form during pregnancy are the brain’s Thalamic connections (around the 33rd week). That would allow for sentience (and sapience), which is why a baby born prematurely (around week 28) might survive, but it’s more likely it won’t. The brain isn’t fully developed, and if it cannot handle any of its sensory input, how can it become a sentient being?
Therefore, if sentience is not just a but THE prerequisite for a soul, then Augustine’s fully-formed argument makes perfect sense. The soul is predicated upon sentience.
The next question would be: Am I actually talking about the soul or the spirit? Hmmmmmmmm…
Yes, it is a slow day at work.