Ethical Perspectives

June 2012

Reactions & Debate by Jeff MCMahan, Dan Weijers and Basil Smith

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Just War
Jeff McMahan

A response to Michael Neu’s “Why McMahan’s Just Wars are only Justified and Why That Matters.” Ethical Perspectives 19/2 (2012): 235-355

Michael Neu is right in claiming that the distinction I have drawn between just and justified wars fails to cohere with another distinction I have drawn between Just Threats and Justified Threats. My failure to see this was a mistake and I am grateful to him for making me aware of it. In this short response to his paper, I indicate how I propose to correct the mistake. My proposal differs from his own recommendation. It is important to be clear and precise about these matters, though I am unconvinced that there is as much at stake as Neu suggests.

We Can Test the Experience Machine
Dan Weijers

A response to Basil Smith’s “Can We Test the Experience Machine?” Ethical Perspectives 18/1 (2011): 29-51.

In his provocative “Can We Test the Experience Machine?”, Basil Smith argues that we should recognise a limit on experimental philosophy. In this response to Smith, I will argue that his limit does not prevent us from usefully testing most experience machine thought experiments, including De Brigard’s inverted experience machine scenarios. I will also argue that, if taken seriously, Smith’s limit has far-reaching consequences for traditional (non-experimental) philosophy as well.

Affect, Rationality, and the Experience Machine
Basil Smith

A response to Dan Weijers’ “We Can Test the Experience Machine.” Ethical Perspectives 19/2 (2012): 261-268

In “Can We Test the Experience Machine?” I address recent tests (i.e. surveys) of the ‘inverted’ experience machine, conducted by Filipe De Brigard. In this scenario, subjects were supposed to imagine they have been living in an experience machine for their entire lives yet it has all been a mistake (De Brigard 2011, 46).

I argue that to test how subjects would react to this, such subjects would have to be in the proper affective state (i.e. experience confusion, incredulity, fear, and uncertainty). De Brigard, therefore, tested the wrong subjects. Moreover, I argue that, generally, when subjects with the wrong affective state respond to surveys, they do so as their ideal selves – as how they want to see themselves. De Brigard did not test control for this, and again tested the wrong subjects (Smith 2011, 45). Since subjects considering the experience machine cannot adhere to these two limits (i.e. being in the right affective state and not answering as their ideal selves), the machine cannot be tested.

Dan Weijers, in his “We Can Test the Experience Machine,” concedes that, if subjects were to imagine the experience machine, they would have “feelings of confusion, incredulity, fear, and uncertainty” (262). Indeed this would have “strong and unpredictable effects” on their estimations of their futures (265). Even so, Weijers objects to my two limitations (i.e. concerning affect and ideal selves). Without such limitations, he says, subjects would make “more rational choices,” and presumably be more reliable. Therefore, my argument is subject to a dilemma: either these two limitations “do not prevent us from usefully testing” the experience machine and similar matters, or if taken seriously, they “apply to nearly all of philosophy” (Weijers 2012, 266).

Concerning the first horn of this dilemma, Weijers incurs three problems. First, Weijers, it seems, construes Nozick and De Brigard as having purposes they do not have, such that their actual purposes – they are clear about these – make such testing either irrelevant, or subject to limits. Second, by insisting that experience machine subjects be rational, Weijers assumes his conclusion, and also, if such strictures were taken seriously, they would render it impossible to test many subjects we care to. Third, Weijers insists that such experience machine studies illuminate our “judgments about our own happiness” (263), and so are useful, but does not say how this is. Since this is so, he only promises an argument, and does not offer one.

Concerning the second horn of this dilemma, Weijers is correct that my two limits “apply to nearly all of philosophy” (266), but he misses the significance of this. First, many thought experiments (e.g. Mary the scientist from Frank Jackson, or zombies from David Chalmers), do not reflect on us, our values, or characters. Philosophers offer such thought experiments, moreover, not to test them, but to elicit our intuitions, to refute a theory, etc. Therefore, while my two limits apply widely (e.g. to thought experiments about morality), they do not affect all of philosophy. However, as we will see, these two limits apply to philosophical thought experiments about morality (e.g. about theft, torture, or our commitments to our fellows). Therefore, many such thought experiments are impossible to test.

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