What disrupts continuity of personal identity?

[4th post in a series, start with the first post here]

I’ve been writing this week about Parfit’s idea that personal identity should be thought of as defined by the continuity or overlap in important psychological properties between the self at different times. One question that’s raised by his work is what are important changes in terms of personal identity? Which changes are important enough to disrupt psychological connectedness to the future self, and which changes are merely superficial, not impacting how connected people feel to their future selves?

Nina Strohminger and Shaun Nichols have a fascinating paper looking at mental changes, specifically those caused by dementia, Alzheimers and ALS (Lou Gehrig’s diseases). They study family members of patients suffering from these diseases, looking at relationships with the patient, as well as perceptions of whether the patient is still the same person.

They find that dementia has the strongest negative effect on relationships to family members, and ALS the least, with Alzheimers somewhere in-between.  These differences in negative effects of the diseases on patients’ relatives can be traced back to the relative’s higher perceptions  of the dementia (vs. ALS) patients as a different person.  These perceptions, fundamentally about continuity of others’ identity, in turn, seem to depend most strongly on the relative’s perceptions that the patient’s morality has changed.

To put it another way, the patient’s amnesia, depression, changes in the patient’s personality, and length of illness all had minimal effects on whether the patient’s relatives saw the patient as no longer the same person.  What mattered the most was the relative’s perception of the patient’s morality having changed (as well as, to a lesser degree, the patient having difficulty speaking).  This points to morality as potentially being at the core of what needs to remain the same for people to feel connected to their future selves.

Stephanie Chen, along with Dan Bartels and I, has looked at this same question in a very different way.  She measured people’s causal maps of aspects of their identity (see an example below), by having people identify which aspects of their identity caused which other aspects. She then asked people to identify which aspects, if changed, would be most disruptive to their identity.

causal-map

She finds that morality is important, but no necessarily the most important, when people are contemplating possible future changes in their own identity.  Instead, what seems to matter the most in this way of looking at it are the causal inter-relationships. Those aspects which are linked to the most other aspects of the self, either as a cause or as an effect, are the ones that are most important for identity.

The aspects that have the most causal connections vary across people.  Of the aspects we tested, the ones that had the most links to other aspects and had the most impact on identity were personal goals and intelligence.  Wholesomeness, loyalty and honesty had somewhat lower levels of both links and perceived impact on identity, on average.

causal-links

These results suggest that what matters for a person’s identity will depend on how that person sees their personal aspects. If I think of my moral values as connected to lots of others aspects of myself, then I am more likely to see a future change in my morality as disrupting the continuity of my identity. But if I see my moral values as occurring separately from other aspects, then I will tend to see changes in those moral values as less disruptive than something else that is more central and connected — perhaps my intelligence, goals or memories.

 

 

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Parfit, connectedness and death

[3d post in a series, start with the first post here]

On Tuesday, I wrote about Derek Parfit’s paper, Personal Identity, and his views about how thinking of the future self as not fully the same person as the present self (i.e., as not fully psychologically connected) might have implications for how people think about death:

“The second consequence which I shall mention is implied in the first. Egoism, the fear not of near but of distant death, the regret that so much of one’s only life should have gone by — these are not, I think, wholly natural or instinctive. They are all strengthened by the beliefs about personal identity which I have been attacking. If we give up these beliefs, they should be weakened.”

This is a view that he took seriously in his own life, and that he evidently found liberating.

In 2015, we organized a conference on personal identity and decision making. Shaun Nichols gave a fascinating talk on work he and his co-authors were doing on exactly this question, including comparing across religions with different views of personal identity. He briefly discusses his research in the video below (at the 1:10 mark).

It turns out not to work for most other people quite as Parfit described in his own views. In Shaun and his co-authors’ experiments, making people more connected did not seem to reduce their anxiety about death. They speculated that when people think about death, they are not thinking in terms of a future self, but are imagining it as occurring in the present.

I also wonder if the psychological will to live transcends how we think of tradeoffs between present and future. One potential implication of how Parfit thinks of death is that we are kind of constantly dying a little bit. Every day’s self is at least a bit disconnected from the previous day’s self, and that previous day’s self is gone. For Parfit, this makes the entire question of death moot, in a way — there is no single long-term enduring self that ceases to exist. But another way of thinking about this is to see your child self as (at least somewhat) dead, and to know that at some point in the future, your future self will consider your present self to be (at least somewhat) dead too.

In some sense that seems right. My 10 year old self is gone, and in a weird way, I kind of miss that kid. A lot of what defined our past selves can remain in our present selves, of course, but some of it is gone. I think for most people, what is gone is a combination of those things that they wanted to change, those changes that are inevitable, and those aspects of the self that somehow just slip away when we’re focused on other things.

So, while I think Parfit’s view resonates with people’s experience to some degree, it’s not clear to me that the implication is to necessarily be less threatened by death.  If a person has low connectedness, believing that the future self will be fundamentally different, then that eventual death of the disconnected future self may be less threatening. But if the low connectedness itself is seen as a kind of gradual death of the current self, thinking in terms of connectedness could feel threatening rather than liberating.

[See the last post here].

More on Parfit

[2d post in a series, start with the first post here]

Vox has a profile of Derek Parfit out today, covering the impact of his ideas on philosophy.

When we were working on the connectedness research I discussed yesterday, it was back in the days of paper surveys, and I brought unused blank surveys home, for my kids to draw on.  At one point, we got into a discussion about it, and I tried to explain to my then 9 year old daughter the idea of connectedness to the future self.  I wasn’t sure that my explanation was making all that much sense to her.  But then a few days later I found this picture:

connected

I think it actually captures the idea of having high connectedness to the future self really well. We age and our bodies change, but if the core that defines me, whatever I think that is, remains the same, then I’m still mainly the same person.

[See the next post here].

Derek Parfit

The philosopher Derek Parfit has died. The New Yorker published an interesting profile of his work a few years ago.

I’ve spent a lot of time in the last several years working with Dan Bartels on research related to Parfit’s thinking. My own knowledge of Parfit’s work was always a bit secondhand. Dan had read his work closely and saw the potential relevance for how people value outcomes in the future, or to put it in psychological and economics terms, for time discounting.  I had been working on time discounting, and Dan got me interested in how Parfit’s ideas might shed light on the topic.

Much of Parfit’s thinking is laid out in his 1984 book Reasons and Persons. His 1971 paper, “Personal Identity” lays out a shorter case for how he thought about present and future selves.

Parfit is interested in an issue widely debated in philosophy, how personal identity can be defined. He starts with a scenario by David Wiggins, in which a person’s brain is removed, split in two, and transplanted into two new bodies, each of which will have the original person’s character and memories. The question is whether the original person has survived, and if so, whether as one or two people? After discussing this case, and an opposite case in which two people’s brains are merged into one, he introduces a third way of thinking about identity:

“But let us look, finally, at a third kind of being.

In this world there is neither division nor union.  There are a number of everlasting bodies, which gradually change in appearance.  And direct psychological relations, as before, hold only over limited periods of time.

Our beings would have one reason for thinking of themselves as immortal.  The parts of each “line” are psychologically continuous.  But the parts of each “line” are not all psychologically connected.  Direct psychological relations hold only between those parts which are close to each other in time. “

In this paper, Parfit proposed that we rethink personal identity in terms of psychological overlap defined by the degree to which psychologically important features are held in common by the present self and a future or past self, which he calls “psychological connectedness”. He goes on to say:

“On this way of thinking, the word ‘I’ can be used to imply the greatest degree of psychological connectedness. When the connections are reduced, when there has been any marked change of character or style of life, or any marked loss of memory, our imagined beings would say, ‘It was not I who did that, but an earlier self.’ They could then describe in what ways, and to what degree, they are related to this earlier self.

This revised way of thinking would suit not only our ‘immortal’ beings.  It is also the way in which we ourselves could think about our lives. And it is, I suggest, surprisingly natural.”

What starts off as an abstract philosophical discussion suddenly has, if you agree with his point of view, clear implications for how we should think about the past and future when making decisions. Parfit goes on to elaborate on the implications for the norm of self-interest. In his view, if a person has low psychological connectedness with the future self, then it makes sense for that person to care less about that future self, and by extension to make decisions that don’t give much weight to long-term consequences. This is presented in normative terms (and has since been widely debated in philosophy).

Descriptively, psychologists and behavioral economists had long noted that people seemed to give more weight to present than future outcomes in making decisions (like choosing $50 now over $100 in 6 months). This occurs to a degree that is difficult to explain in purely economic terms (i.e. in terms of interest rates and inflation).

My first year at Chicago, I saw Dan present a paper he had been working on with Lance Rips, showing that differences in how people weighted near vs. distant future outcomes against the present could be at least partially explained by how people’s subjective psychological connectedness declines over greater lengths of time.

Dan and I then looked at how people who are (or are made to be) more or less connected to their future selves are more vs. less patient in economic decisions. We also studied how the effect of connectedness on decisions depends on whether the person tends to think about (or is reminded to think about) the future consequences of their decisions. Most recently, Stephanie Chen, Dan and I have investigated  which disruptions to an aspect of a person’s identity would have the most impact on reducing subjective connectedness. Dan and quite a few other people (including Hal Hershfield and Shane Frederick) have also been studying these and related questions in the last few years, and I’ve just finished a review paper summarizing the current state of research on this topic.

In Personal Identity, after discussing the norm of self-interest, Parfit then goes on to discuss possible implications for how people might think about death:

“The second consequence which I shall mention is implied in the first. Egoism, the fear not of near but of distant death, the regret that so much of one’s only life should have gone by — these are not, I think, wholly natural or instinctive. They are all strengthened by the beliefs about personal identity which I have been attacking. If we give up these beliefs, they should be weakened.”

[First in a series, see the next post here].