In sum, if it seems that I have simply misunderstood what Kant and deontology are all about,
it's because I am advancing an alternative hypothesis to the standard Kantian/deontological understanding
of what Kant and deontology are all about. I am putting forth an empirical hypothesis
about the hidden psychological essence of deontology, and it cannot be dismissed a priori
for the same reason that tropical islanders cannot know a priori whether ice is a form of water.
- Joshua Greene's (2008, p. 74) 'The secret joke of Kant's soul'
The Moral Brain
Our capacities for moral reasoning, moral judgment, and moral decision-making are underwritten by certain moral belief-forming dispositions that have been naturally selected for
We share these capacities with our Pleistocene epoch hunter-gatherer ancestors
Our moral beliefs are explained by the evolutionary process and its chief mechanism of natural selection
General structure of an evolutionary debunking argument (Kahane, 2011):
P1 (Causal): Agent X's belief that p is explained by process S.
P2 (Epistemic): S is an off-track (i.e. non-truth-tracking) process.
P3 (Conditional): If S is an off-track process and X's belief that p is explained by S, then X's belief that p is unjustified.
C: ∴ X's belief that p is unjustified. (modus ponens)
Evolutionary debunking arguments serve to remind us that an understanding of the etiology of our moral beliefs may result in the undermining of their justificatory status
We end up with good reason to be skeptical about those moral beliefs that are implicated in the distorting influences and pressures of our evolutionary history
Q: Can we save any of our moral beliefs from evolutionary debunking arguments?
A runaway train or trolley is hurtling along the main track
If left unimpeded, it will run over and kill 5 hapless individuals on the main track
You are on a footbridge that is above the main track
Standing alongside you on that footbridge is an individual of considerable girth
You have performed certain calculations and are aware that you could push this fat person off the footbridge, you could stop the runaway train, and save the 5 hapless individuals
Q: What should you do?
φ1 — push the fat person off the footbridge (kill 1 to save 5)
φ2 — refrain from doing so
People typically decide in favour of φ2 in the footbridge dilemma
φ2 has been described as a characteristically deontological response
φ2 is motivated by a powerful negative response to the 'up close and personal' nature of violence (i.e. a direct way of killing)
This powerful negative response has been naturally selected for
There tends to be more activity in the VMPFC (ventromedial prefrontal cortex) and amygdala for characteristically deontological responses
In addition, the neural response is more immediate