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  • 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




    1. 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
    2. We share these capacities with our Pleistocene epoch hunter-gatherer ancestors
    3. Our moral beliefs are explained by the evolutionary process and its chief mechanism of natural selection


    4. General structure of an evolutionary debunking argument (Kahane, 2011):
    5. P1 (Causal): Agent X's belief that p is explained by process S.
    6. P2 (Epistemic): S is an off-track (i.e. non-truth-tracking) process.
    7. 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.
    8. C: ∴ X's belief that p is unjustified. (modus ponens)


    9. 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
    10. 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


    11. Q: Can we save any of our moral beliefs from evolutionary debunking arguments?




    Footbridge dilemma

    Image source: http://www.joshua-greene.net/research/moral-cognition



    1. The footbridge dilemma:
    2. A runaway train or trolley is hurtling along the main track
    3. If left unimpeded, it will run over and kill 5 hapless individuals on the main track
    4. You are on a footbridge that is above the main track
    5. Standing alongside you on that footbridge is an individual of considerable girth
    6. 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

    7. Q: What should you do?


    1. φ1 — push the fat person off the footbridge (kill 1 to save 5)
    2. φ2 — refrain from doing so

    3. People typically decide in favour of φ2 in the footbridge dilemma
    4. φ2 has been described as a characteristically deontological response
    5. φ2 is motivated by a powerful negative response to the 'up close and personal' nature of violence (i.e. a direct way of killing)
    6. This powerful negative response has been naturally selected for

    7. There tends to be more activity in the VMPFC (ventromedial prefrontal cortex) and amygdala for characteristically deontological responses
    8. In addition, the neural response is more immediate





    Trolley dilemma

    Image source: http://www.joshua-greene.net/research/moral-cognition



    1. The trolley dilemma:
    2. A runaway train or trolley is hurtling along the main track
    3. If left unimpeded, it will run over and kill 5 hapless individuals on the main track
    4. You are in possession of a lever, the pulling of which will divert the train from the main track to the side track
    5. There is an individual on the side track who will get run over by the train if you decide to pull the lever

    6. Q: What should you do?


    1. φ1 — pull the lever (kill 1 to save 5)
    2. φ2 — refrain from doing so

    3. People typically decide in favour of φ1 in the footbridge dilemma
    4. φ1 has been described as a characteristically consequentialist response
    5. φ1 may be characterized as a more indirect way of killing
    6. Indirect ways of killing (e.g. by pulling a lever or pulling the trigger of a gun) are more recent and do not arouse a similarly innate response

    7. There tends to be more activity in the DLPFC (dorsolateral prefrontal cortex) for characteristically consequentialist responses
    8. In addition, the neural response is more delayed