1. See, for example, Farah MJ, Smith ME, Gawuga C, Lindsell D, Foster D. Brain imaging and brain privacy: A realistic concern? Journal of Cognitive Neuroscience 2008;21:119–27. Wolpe PR, Foster KR, Langleben DD. Emerging neurotechnologies for lie-detection: Promises and perils. The American Journal of Bioethics 2010;10:40–8. Sahakian BJ, Gottwald J. Sex, Lies, and Brain Scans: How fMRI Reveals What Really Goes on in Our Minds. Oxford: Oxford University Press; 2017. Poldrack RA. The risks of reading the brain. Nature 2017;541:156. Poldrack, RA. The New Mind Readers: What Neuroimaging Can and Cannot Reveal about Our Thoughts. Princeton: Princeton University Press; 2018. Baker C. Promises and pitfalls of imaging the brain. Nature 2018;562:340–2. A usual question has been “What the current conceptual and methodological limitations are.”

2. See, for example, Buller T. Brains, lies, and psychological explanations. In: Illes J, ed. Neuroethics. Oxford: Oxford University Press; 2006. Of course, there is a plenty of discussion about “neuro-reductionism” and similar issues. See, for example, Buller T. Neurotechnology, invasiveness and the extended mind. Neuroethics 2013;6:593–605. Chandler J. Neurolaw and neuroethics. Cambridge Quarterly of Healthcare Ethics 2018;27:590–8. By “principled” limitations, I refer to limitations that are not contingent to the advances of future neuroscience.

3. Would it be important to hear what others say, even if the scanners could easily and accurately show a one-to-one relationship between particular psychological states and particular brain activities?

4. In that kind of world, we would not need to talk to one another simply because chatting is funny, for ex hypothesis scanning would be even funnier. Furthermore, in that kind of world, other people’s words would not necessarily reveal anything new of the speaker’s intentionally concealed thoughts and emotions, for we could scan those things as easily as other cognitive states, that is, if we wanted to.

5. See note 1, Poldrack 2018. See also Räikkä J, Smilansky S. The ethics of alien attitudes. The Monist 2012;95:511–32.

6. To tell someone that “It is a rainy day” is an act that is not usually accompanied by another act, namely, the act of actively thinking that “It is a rainy day.” Surely, we could do both acts at the same time, but normally we do not. If people committed separate “mental assertions” while making ordinary assertions, then the brain scanner could scan the “mental assertions.”

7. In many ways, we are dependent on other people’s knowledge. We know that certain mushrooms are poisonous, that smoking causes cancer, that the battle of Waterloo happened, how to use certain words, and where we were born only because someone has told us these things. We are social creatures, and it is not clear whether we do or even could possess any knowledge which is not based on testimony, either directly or indirectly. Furthermore, it is rather optimistic to claim that, afterwards, we can and do check our testimony-based beliefs by more reflective and critical methods. This does not seem to be true. For instance, we have known the names of some capital cities for almost all our lives without ever bothering to check whether the information we have is correct. In many cases, learning from teachers, colleagues, experts, textbooks, documents, and relatives seems to be the only way we can know certain things. Cf. Fricker E. Testimony and epistemic autonomy. In: Lackey J, Sosa E, eds. The Epistemology of Testimony. Oxford, UK: Clarendon Press; 2006.

8. Cf. Watson 2004, at 66. Much of the discussion concerning the assurance view is actually a debate about the nature of assertions and their relation to promises.

9. Peirce C. Belief and judgment. In: Collected Papers V. Cambridge, MA: Harvard, 1934. Cited by Watson G. Asserting and promising. Philosophical Studies 2004;117:57–77.

10. Ross A. Why do we believe what we are told. Ratio 1986;28:69–88. Hinchman E. Telling as inviting to trust. Philosophy and Phenomenological Research 2005;70:562–587. Origgi G. What does it mean to trust in epistemic authority? In: 7th Annual Roundtable of Philosophy of Social Science, Columbia University; 2005: 1–26. See also Dannenberg J. Serving two masters: Ethics, epistemology, and taking people at their word. Australasian Journal of Philosophy 2019;98:1–18.

11. Moran R. Getting told and being believed. In: Lackey J, Sosa E, eds. The Epistemology of Testimony. Oxford, UK: Clarendon Press; 2006: 250–72.

12. See note 11, Moran 2006, at 280.

13. Of course, if a person tells us that she will go to Florence in the spring, that does not imply that she has a promise-based obligation to go there. Cf. Friedrich D, Southwood N. Promises and trust. In: Sheinman H, ed. Promises and Agreements: Philosophical Essays. Oxford: Oxford University Press; 2011: 277–94.

14. See note 11, Moran 2006, at 291.

15. See note 11, Moran 2006, at 295.

16. See note 11, Moran 2006, at 294.

17. See note 11, Moran 2006, at 297.

18. See note 11, Moran 2006, at 283.

19. See note 11, Moran 2006, at 289.

20. See note 11, Moran 2006, at 277.

21. See note 11, Moran 2006, at 277.

22. See note 11, Moran 2006, at 277. Moran (p. 278) writes that, on the assurance view, “going behind his back to learn his beliefs would not be better, or even just as good. Rather, it is essential to the distinctive reason for belief that I get from assertion that it proceeds from something freely undertaken by the other person. Only as a free declaration does it have that value for me.”

23. See note 11, Moran 2006, at 279.

24. See note 11, Moran 2006, at 292. Moran notices (p. 292) that we “express our freedom not only in our considered actions but also in the actions that go wrong or are forced upon us, and the outbursts that we immediately regret.” Thus, his argument cannot be criticized by claiming that it assumes that assertions that are made under pressure do not have similar epistemic significance as those that are made freely. For such criticism, see Owens D. Testimony and assertion. Philosophical Studies 2006;130:105–29. Assertions can be relevantly “free” even when they are forced upon us. Owens (p. 119) formulates the key message of the assurance view by pointing out that we “may learn what someone believes from a brain scan but inferring that he is right from the scan is not an instance of learning by trusting him.”

25. See note 11, Moran 2006, at 295.

26. See note 11, Moran 2006, at 289.

27. See note 11, Moran 2006, at 289. See also Moran R. The Exchange of Words: Speech, Testimony, and Intersubjectivity. Oxford: Oxford University Press; 2018, at 58.

28. The point is not that we get more certain information by listening to reliable and trustworthy people. As Moran writes: “When someone gives me his assurance that it’s cold out he explicitly assumes a certain responsibility for what I believe. What this provides me with is different in kind, though not necessarily in degree of certainty, from beliefs I might have read off from his behavior, just as what I gain from his declaration of intention differs from the firm expectation I may form from knowing his habits.” See note 11, Moran 2006, at 278.

29. Cf. Zagzebski LT. Epistemic Authority. Oxford: Oxford University Press; 2012. Zagzebski (p. 123) writes that “there is no explanation for feeling let down when the testimony is false if testimony is evidence.”

30. To some extent, the assurance view explains why we are so interested in what we are told, and why we probably would be interested in the words of others even if we could scan their brains in a second. Of course, one may ask whether people are reasonable when they implicitly assume that others are trustworthy and reliable. For usually there is no way of checking the reliability of the testimony or the trustworthiness of the testifier, and at least in some cases we should check these things. Cf. Guerrero AA. Living with ignorance in a world of experts. In: Peels R, ed. Perspectives on Ignorance from Moral and Social Philosophy. New York, NY: Routledge; 2017: 156–85.

31. Quite often we do not think that the speaker is trustworthy and reliable, but we are still very interested in what we are told and how others talk to us.

32. Goffman E. The Presentation of Self in Everyday Life. New York, NY: Woodstock; 1973.

33. See note 32, Goffman 1973, at 17.

34. James W. The Principles of Psychology. Cambridge, MA: Harvard University Press; 1983, at 281.

35. Simmel G. The secret and the secret society. In Wolff KH, trans. Part IV of The Sociology of Georg Simmel. Florence, MA: The Free Press; 1950, at 311–2. Cited in Velleman JD. The genesis of shame. Philosophy & Public Affairs 2001;30:27–52.

36. Velleman JD. How We Get Along. Cambridge: Cambridge University Press; 2009. Velleman does not use the label of the “theatrical model.”

37. Self-presentation is quite often seen as a form of strategic action. See, for example, Leary MR. Self-Presentation: Impression Management and Interpersonal Behavior. Boulder, CO: Westview Press; 1995.

38. See note 36, Velleman 2009, at 14.

39. See note 36, Velleman 2009, at 14.

40. See note 36, Velleman 2009, at 14.

41. See note 36, Velleman 2009, at 17.

42. See note 36, Velleman 2009, at 17.

43. See note 36, Velleman 2009, at 18.

44. See note 36, Velleman 2009, at 19.

45. See note 36, Velleman 2009, at 22.

46. See note 36, Velleman 2009, at 26.

47. See note 36, Velleman 2009, at 94. He writes that if “a person were not presenting himself to himself, he would not be an autonomous agent capable of practical reasoning.” Thus, self-presentation is not primarily a social issue. Velleman argues: “Putting an outward face on our behavior sounds like an essentially social enterprise, but I think that this enterprise is inherent in the structure of the individual will. Even Robinson Crusoe chose which of his desires to act on, and his need to understand and coordinate his activities required him to make choices by which he could consistently abide. He therefore lived in accordance with a persona that he composed, even though there was no audience for whom he composed it. Or, rather, he composed this persona for an audience consisting only of himself, insofar as it was designed to help him keep track and make sense of his solitary life. So even Robinson Crusoe had distinct overt and covert selves—the personality that he acted out, and a personality that differed from it by virtue of including all of the inclinations and impulses on which he chose not to act.” See note 35, Velleman 2001, at 35.

48. See note 36, Velleman 2009, at 27.

49. See note 36, Velleman 2009, at 27. Emphasis added.

50. See note 36, Velleman 2009, at 28. Velleman (p. 25, footnote 16) argues that in certain circumstances, a person’s practical thinking may function “like a theatrical prompter, following along in the script independently while standing ready to intervene if errors occur. The ability to think along with oneself in this way, with thoughts that neither follow nor lead one’s behavior, depends on a degree of self-knowledge that can be attained only through long practice in the more deliberate, thought-first mode of action. It is a long-term accomplishment of rational agency.”

51. See note 36, Velleman 2009, at 102. Of course, authenticity does not require that one is brutally frank. As Velleman (p. 69) explains, one of your “motives may be a desire for social harmony, which you can best promote in some circumstances by assuming an amiable expression and keeping your true sentiments to yourself. In those circumstances, putting on an amiable expression makes more sense than baring your soul. A pretense of this kind is not usually designed to deceive, however. On the contrary, your social face is meant to be seen for what it is, a mask adopted in order to promote social harmony. This mask provides you and others with a shared basis for understanding your behavior, on two levels. On the surface, you proceed to act in ways that would make sense in light of the amiable attributes that your face pretends to express, and others pretend to understand your actions in terms of those attitudes. At deeper level, all parties understand the surface performance as a pretense motivated by a desire for social harmony.”

52. See note 36, Velleman 2009, at 62.

53. See note 36, Velleman 2009, at 70.

54. See note 36, Velleman 2009, at 71.

55. See note 36, Velleman 2009, at 66. See also Kusch M. How minds and selves are made: Some conceptual preliminaries. Interaction Studies 2005;6:21–34. “My self-classification as a member of a club is in good part dependent upon how other club members classify me.”

56. See note 36, Velleman 2009, at 67–68. Velleman refers to Swann WB. Resilient Identities: Self, Relationships, and the Construction of Social Reality. New York, NY: Basic Books; 1999, at 70.

57. Goffman distinguishes between the expression that a person gives and what he gives off: “The first involves verbal symbols or their substitutes which he uses admittedly and solely to convey the information what he and the others are known to attach to these symbols. This is communication in the traditional and narrow sense. The second involves a wide range of action that others can treat as symptomatic of the actor, the expectation being that the action was performed for reasons other than the information conveyed in this way. As we shall have to see, this distinction has only initial validity. The individual does of course intentionally convey misinformation by means of both of these types of communication, the first involving deceit, the second feigning.” See note 32, Goffman 1973, at 2.

58. Possibly, the speaker wants to present herself as a person who would like to talk about weather rather than about something more serious or personal.

59. When a person tells another person, say, that it is a rainy day, the hearer need not learn much about the weather. An important reason why we are so interested in what people say is that their words give information about the speakers themselves. In particular, their assertions tell how they would like to present themselves in the social context the assertions are uttered, and what kind of social persona they would like to offer in that specific context. Small talk may give an impression that people involved are not interested in the truth at all, and that they are (morally) worse persons than ordinary liars who, after all, are interested in the truth when they try to make other people believe things that are not true. However, it is likely that people who talk about the weather are interested in the truth, namely, truth about themselves and other people (if not the truth about the weather). For a discussion, see Frankfurt HG. On Bullshit. Princeton: Princeton University Press; 2005.

60. Of course, when something private about you is showing without your intention, you have failed to manage your public image, and others can certainly make use of such failure. See note 35, Velleman 2001, at 38.

61. Suppose that a person is able to communicate only by means of a scanner-like device. That would show that in some cases people are capable of intentional assertions only by means of a scanner. (The technology is already available. Adrian Owen has made important work in this field.)

62. I am not suggesting that “two-person neuroscience” is not possible. Neuroimaging of two interacting subjects to uncover brain mechanisms supporting social interaction is obviously something that has been already done. Possibly, we are able to interpret the data only by understanding the relevant social situation, and this brings social issues into the picture. The interpretation of the data need not be passive (in the sense of “looking” at the picture): it may require the interpreter to “participate” or “contribute,” in a way or another.

63. Lackey J. Testimony: Acquiring knowledge from others. In: Goldman AI, Whitcomb D, eds. Social Epistemology: Essential Readings. Oxford: Oxford University Press; 2011: 71–91.

64. Hazlett A. Review of How We Get Along. Notre Dame Philosophical Reviews. Cambridge: Cambridge University Press; 2009.

65. See note 64, Hazlett 2009. Hazlett argues that there is a sense of “inauthenticity” in which all of our actions are inauthentic if Velleman’s theory is correct: “However, there is something more involved in the everyday idea that theatrical acting is a paradigm of inauthenticity. It’s the fact that acting seems to involve the aforementioned ‘one thought too many’: inauthentic people, we want to say, do not simply do what they want to do, but in addition they always think about what someone like them is supposed or expected to do under the circumstances that they are in. The decisions of the inauthentic person are always mediated by their self-conceptions; the decisions of the authentic person are not. In this sense of ‘inauthenticity’, Velleman’s paradigm of acting for reasons is also a paradigm of inauthenticity.”

66. See note 1, Baker 2018, at 340–1. (Also published as “The Brain Decoders.”)

67. See note 1, Poldrack 2018, at 77 argues that the “use of neuroimaging to detect conscious awareness in people with brain injuries is a major advance that shows the real-world utility of fMRI decoding.”

68. See note 1, Sahakian, Gottwald 2017, at 21.

69. See note 36, Velleman 2006, at 215, where Velleman points out that “people tend to manifest not just what they are feeling but also what they represent themselves as feeling. Whether they behave angrily depends, not just on whether they are angry, but on whether they interpret their feelings by updating their autobiographies with the attribution ‘I’m angry’.” Thus, if a brain scanner reveals what a person is “really thinking,” that does not mean that the person will really behave in the way her most primitive thoughts might predict.

70. Notice also that presenting something publicly forces one think about the issue, and this process may alter her beliefs. Cf. Moran R. Philosophical Imagination: Selected Essays. New York, NY: Oxford University Press; 2017, at 286.

71. Robinson D. The new mind readers: A review. Science Magazine 2018 Sep 4.

72. See note 71, Robinson 2018.

73. Kant I. Anthropology from a Pragmatic Point of View. Carbondale, IL: Southern Illinois University Press; 1996, at 250. It is nowadays possible to translate a person’s thoughts into recognizable speech by monitoring her brain activity.