How can I credibly commit to others?

Francesca Bonalumi — PhD can­did­ate, Department of Cognitive Science, Central European University



Imagine that you plan to go to the gym with your friend Kate. You decide togeth­er to meet in the lock­er room at 6pm. Why would you expect that Kate will hon­our this agree­ment to meet you at the gym? Now, ima­gine that at 5.30pm you dis­cov­er that some oth­er friends are gath­er­ing at 6pm, and you would love to join them. What restrains you from join­ing them, even if this is now your pre­ferred option? Your answers to these kinds of dilem­mas that are faced in every­day life will prob­ably involve some ref­er­ence to the fact that a com­mit­ment was in place between you and Kate.

The notion of a com­mit­ment is worth invest­ig­at­ing, in part, because it applies to such a wide vari­ety of cases: we are com­mit­ted to our part­ners, our faith, our work, our prom­ises, our goals, and even ourselves. Although there is an obvi­ous sim­il­ar­ity between all these situ­ations, I will restrict this post to instances of inter­per­son­al com­mit­ment, namely those com­mit­ments that are made by one indi­vidu­al to anoth­er indi­vidu­al (cfr. Clark 2006). According to a stand­ard philo­soph­ic­al defin­i­tion of inter­per­son­al com­mit­ment, a com­mit­ment is a rela­tion among one com­mit­ted agent, one agent to whom the com­mit­ment has been made, and an action which the com­mit­ted agent is oblig­ated to per­form (Searle 1969; Scanlon 1998).

The abil­ity to make and assess inter­per­son­al com­mit­ments is cru­cial in sup­port­ing our proso­cial beha­viour: being motiv­ated to com­ply with those courses of action that we have com­mit­ted to, and being able to assess wheth­er we can rely on oth­ers’ com­mit­ments, enables us to per­form a wide range of jointly coordin­ated and inter­per­son­al activ­it­ies that wouldn’t oth­er­wise be feas­ible (Michael & Pacherie, 2015). This abil­ity requires psy­cho­lo­gic­al mech­an­isms that induce indi­vidu­als to fol­low rules or plans even when it is not in their short-term interests: this can sus­tain phe­nom­ena from the inhib­i­tion of short-term self-interested actions to the motiv­a­tion for mor­al beha­viour. I will focus on one key, yet under­ap­pre­ci­ated, aspect of this rela­tion which sus­tains the whole act of com­mit­ting: how the com­mit­ted agent gives assur­ance to the oth­er agent that she will per­form the rel­ev­ant action. That is, how she makes her com­mit­ment cred­ible.

Making a com­mit­ment can be defined as an act that aims to influ­ence anoth­er agent’s beha­viour by chan­ging her expect­a­tions (e.g. my com­mit­ting to help a friend influ­ences my friend’s beha­viour, inso­far as she can now rely on my help), and by this act the com­mit­ter gains addi­tion­al motiv­a­tion for per­form­ing the action that she com­mit­ted to (Nesse 2001; Schelling 1980). The key ele­ment in all of this is cred­ib­il­ity: how do I cred­ibly per­suade someone that I will do some­thing that I wouldn’t do oth­er­wise? And why would I remain motiv­ated to do some­thing that is no longer in my interest to do? Indeed, a dilemma faced by recip­i­ents in any com­mu­nic­at­ive inter­ac­tion is determ­in­ing wheth­er they can rely on the sig­nal of the sender (i.e. how to rule out the pos­sib­il­ity that the sender is send­ing a fake sig­nal) (Sperber et al., 2010). Likewise, in a cooper­at­ive con­text the prob­lem for any agent is how to dis­tin­guish between a cred­ible com­mit­ment and a fake com­mit­ment, and how to sig­nal a cred­ible com­mit­ment without being mis­taken for a defect­or (Schelling, 1980).

The most per­suas­ive way to make my com­mit­ment cred­ible is to dis­card altern­at­ive options in order to change my future incent­ives, such that com­pli­ance with my com­mit­ments will remain in my best interests (or be my only pos­sible choice). Odysseus instruct­ing his crew to tie him to the mast of the ves­sel and to ignore his future orders is one strong example of com­mit­ting to res­ist the Sirens’ call in this man­ner; avoid­ing cof­fee while try­ing to quit smoking (when hav­ing a cigar­ette after a cof­fee was a well-established habit) is anoth­er example.

How can we per­suade oth­ers that our com­mit­ments are cred­ible when incent­ives are less tan­gible, and altern­at­ive options can­not be com­pletely removed? Consider a mar­riage, in which both part­ners rely on the fact that the oth­er will remain faith­ful even if future incent­ives change. Emotions might be one way of sig­nalling my will­ing­ness to guar­an­tee the exe­cu­tion of the com­mit­ment (Frank 1998; Hirshleifer 2001). If two indi­vidu­als decide to com­mit to a rela­tion­ship, the emo­tion­al ties that they form ensure that neither will recon­sider the costs and bene­fits of the rela­tion­ship[1].  Likewise, if, dur­ing a fight, one indi­vidu­al dis­plays uncon­trol­lable rage, she is giv­ing her audi­ence reas­on to believe that she won’t give up the fight even if con­tinu­ing to fight is to her dis­ad­vant­age. One reas­on that emo­tions are taken to be cred­ible is because they are allegedly hard to con­vin­cingly fake: some stud­ies sug­gest that humans are intu­it­ively able to recog­nize the appro­pri­ate emo­tions when observing a face (Elfenbein & Ambady, 2002), and to some extent humans are able to effect­ively dis­crim­in­ate between genu­ine and fake emo­tion­al expres­sion (Ekman, Davidson, & Friesen, 1990; Song, Over, & Carpenter, 2016).

Formalising a com­mit­ment by mak­ing prom­ises, oaths or vows is anoth­er way of increas­ing the cred­ib­il­ity of your com­mit­ment. Interestingly, with such form­al­ised declar­a­tions people not only mani­fest an emo­tion­al attach­ment to the object of the com­mit­ment; they also sig­nal a will­ing­ness to put their repu­ta­tion at risk. This is because the more pub­lic the com­mit­ment is (and the more people are aware of the com­mit­ment), the high­er the repu­ta­tion­al stakes will be for the com­mit­ted individual.

Securing a com­mit­ment by alter­ing your incent­ives, by risk­ing your repu­ta­tion, or by express­ing it via emo­tion­al dis­plays are import­antly sim­il­ar: the ori­gin­al set of mater­i­al pay­offs for per­form­ing each action changes, because now the costs of smoking or unty­ing your­self from the mast of a ves­sel are too high (if it is even still pos­sible to pay these costs). But we can ima­gine the emo­tion­al costs paid in case of a fail­ure (e.g. the dis­ap­point­ment from slip­ping back into our undesir­able habit of smoking), as well as the social costs (e.g. dam­age to our repu­ta­tion as a reli­able indi­vidu­al), as incent­ives to com­ply with the action that was com­mit­ted to (Fessler & Quintelier 2014).



Cheating Non-cheating
Before the commitment p -p
After the commitment p – (m + r + e) -p

Fig.1 Payoff mat­rix of the decision to cheat on your part­ner: p is the pleas­ure you get out of cheat­ing, where­as m is the mater­i­al costs paid in such cases (e.g. a costly divorce), r is the repu­ta­tion­al costs and e is the emo­tion­al bur­den that will be paid in such cases. When p is not high­er than the sum of r, m and e, and the indi­vidu­al accur­ately pre­dict the like­li­hood of these out­comes, we’ll have a situ­ation in which break­ing a com­mit­ment is not worthwhile.


Consistent with the idea that com­mit­ments change your pay­off mat­rix (see Fig.1), sev­er­al stud­ies have shown that com­mit­ments facil­it­ate coordin­a­tion and cooper­a­tion in mul­tiple eco­nom­ic games. Promises were found to increase an agent’s trust­worthy beha­viour as well as her partner’s pre­dic­tions about her beha­viour in a trust game (Charness and Dufwenberg 2006), and they were found to increase one’s rates of dona­tions in a dic­tat­or game (Sally 1995; Vanberg 2008). Spontaneous prom­ises have also been found to be pre­dict­ive of cooper­at­ive choices in a Prisoner’s Dilemma game (Belot, Bhaskar & Van de Ven 2010). The will­ing­ness to be bound to a spe­cif­ic course of action (e.g. as Ulysses) has also been found to be highly bene­fi­cial in Hawk-Dove and Battle-of-Sexes games, as com­mit­ted play­ers are more likely to obtain their pre­ferred out­comes (Barclay 2017).

Interestingly, the pay­off struc­tures that an agent faces when they make a com­mit­ment is sim­il­ar to the pay­off struc­ture of a threat: If you are involved in a drivers’ game of chick­en, the out­come you want is the one in which you don’t swerve. But your part­ner prefers the out­come in which she does not swerve, and the worst out­come would be the one in which the two cars crash because neither of you swerved. The key factor is, again, wheth­er you can cred­ibly sig­nal to the oth­er driver that you won’t spin the wheel, no mat­ter what.

Some of the same means by which cred­ib­il­ity can be con­veyed in cases com­mit­ment apply to threats as well. For instance, one effic­a­cious way by which you can cred­ibly per­suade the oth­er driver is by remov­ing the steer­ing wheel and throw­ing it out of the win­dow, thereby phys­ic­ally pre­vent­ing your­self from chan­ging the dir­ec­tion of your car (Kahn 1965); anoth­er is by play­ing a war of nerves, con­vey­ing the idea that you are so emo­tion­ally con­nec­ted to your goal that you would be will­ing to pay the highest cost if necessary.

Threat is an inter­est­ing phe­nomen­on to con­sider when invest­ig­at­ing the role of cred­ib­il­ity in com­mit­ment because it might help us to under­stand how com­mit­ment works, and how threat and com­mit­ment might have evolved in sim­il­ar fash­ion. What leads a non-human anim­al to cred­ibly sig­nal an inten­tion to behave in a cer­tain way to its audi­ence, and what lead its audi­ence to rely on this sig­nal, is highly rel­ev­ant for invest­ig­at­ing com­mit­ment. It is still uncer­tain just how threat sig­nals have sta­bil­ized evol­u­tion­ar­ily, giv­en that a select­ive pres­sure for fak­ing the threat would also be evol­u­tion­ar­ily advant­age­ous (Adams & Mesterton-Gibbons 1995). The same select­ive pres­sure apply to human threats and com­mit­ments: if the goal is to sig­nal future com­pli­ance to an action in order to change the audience’s beha­viour (by chan­ging her expect­a­tions), what motiv­ates us to then com­ply to that sig­nal instead of, say, simply tak­ing advant­age of the change in our audience’s behaviour?

In oth­er words, the phe­nomen­on of com­mit­ment is intrins­ic­ally tied to the prob­lem of recog­nising (and maybe even pro­du­cing) fake sig­nals, and deceiv­ing oth­ers, just as in the case of mak­ing a threat. That being said, it is worth keep­ing in mind that the phe­nomen­on of threat dif­fers import­antly from the phe­nomen­on of com­mit­ment, inso­far as the former does not entail any motiv­a­tion for proso­cial beha­viour. In this respect, the phe­nom­ena of quiet calls and nat­al attrac­tion, in which anim­als sig­nal poten­tial cooper­a­tion or a dis­pos­i­tion not to engage in a fight, are also worth invest­ig­at­ing fur­ther for the sake of bet­ter under­stand­ing how cred­ib­il­ity can be estab­lished in the case of com­mit­ment (Silk 2001).

Most of our social life is built upon com­mit­ments that are either impli­cit or expli­citly expressed. We expect people to do things even in the absence of a verbal agree­ment to do so, and we act in accord­ance with these expect­a­tions. Investigating the factors that carry this motiv­a­tion­al force, such as cred­ib­il­ity, is the next big chal­lenge in bet­ter grasp the com­plex­it­ies of this import­ant notion, and would help us to bet­ter under­stand its onto­gen­et­ic and phylo­gen­et­ic development.



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[1] Indeed, mar­riage itself may be a way of increas­ing the like­li­hood that a com­mit­ment will be respec­ted in the future. This is because form­al­ising the rela­tion­ship in this man­ner increases the exit costs of a relationship.