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Preview: Ethics vs Physics

In the domain of physics, almost no one today would advocate basing a theory on how things seem. Historically, this involved lengthy (and bloody) struggle. Thoughtful people can find themselves unable to give up appearances even in the face of overwhelming evidence. How are things different in the ethical domain?

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If the slides are not working, or you prefer them full screen, please try this link. The recording is available on stream and youtube.


The following lectures will involve some details about cognitive psychology and intricate philosophical arguments. If, like me, you find this sort of thing absorbing, do skip this section. It is a preview for anyone who wants a sense of the main conclusion we are heading for.

I hope the preview will be provocative enough to generate interest in the details about cognitive psychology and intricate philosophical arguments.

What Is the Envisaged Conclusion

The envisaged conclusion (not yet argued for) is twofold:

  1. Discoveries in moral psychology provide good reason not to rely on not-justified-inferentially premises about particular scenarios in arguing for (or against) ethical principles (see Greene contra Ethics (Railgun Remix)).

  2. Discoveries in moral psychology could no more undermine, or support, ethical principles than discoveries about physical cognition could undermine or support theories in physics. (Unless the ethics-vs-linguistics comparison is right.)


In the final part of the lecture recordings (last slide), the discussion of scientific discoveries should be limited to discoveries in moral psychology.

The claim under consideration is that discoveries in moral psychology could no more undermine, or support, ethical principles than discoveries about physical cognition could undermine or support theories in physics.

Which comparison: Linguistic or Physical?

In this lecture, I am comparing ethical to physical cognition (and to numerical cognition, and to mindreading). An alternative would be to compare ethical to linguistic cognition. If we do this, we are likely to evaluate the main argument differently.

Each comparison has different advantages, although what their advantages are may depend on your metaethical view (which is beyond the scope of this course).

Although I focus on the comparison with physical cognition, I attempt to indicate which bits of the argument might be different if we relied on a comparison with linguistic cognition in the notes. (But not in the slides or recordings.)

Historical Context for the Vertical Motion Example

Moletti (2000, p. 147), who was Galileo’s predecessor in mathematics at Padua, reports an early (1576 or earlier) experiment on the motion of objects launched vertically in a dialogue:

‘PR. […] Aristotle gave rise to doubts by saying that through one and the same medium the speed of things that are moved in natural movement, being of the same nature and shape, is as their powers. That is, if we were to let fall from the top of a tall tower two balls, one of twenty pounds of lead and the other of one pound, also of lead, that the movement of the larger would be twenty times faster than that of the smaller.

‘AN. This seems sufficiently reasonable to me; in fact, if I were asked I would grant it as a principle.

‘PR. You would be mistaken; in fact, both arrive at one and the same time, even if the test were done not once but many times. But what is more, a ball of wood, either larger or smaller than one of lead, let fall from the same height at the same time as the lead ball, would descend and touch the earth or ground at the same moment in time.’


not-justified-inferentially : A claim (or premise, or principle) is not-justified-inferentially if it is not justified in virtue of being inferred from some other claim (or premise, or principle).
Claims made on the basis of perception (_That jumper is red_, say) are typically not-justified-inferentially.
Why not just say ‘noninferentially justified’? Because that can be read as implying that the claim is justified, noninferentially. Whereas ‘not-justified-inferentially’ does not imply this. Any claim which is not justified at all is thereby not-justified-inferentially.
unfamiliar problem : An unfamiliar problem (or situation) is one ’with which we have inadequate evolutionary, cultural, or personal experience’ (Greene, 2014, p. 714).


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Greene, J. D. (2014). Beyond Point-and-Shoot Morality: Why Cognitive (Neuro)Science Matters for Ethics. Ethics, 124(4), 695–726.
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