Study on the Effectiveness of Commitment Speech Act from the Perspective of Force Dynamics Theory -- An Empirical Study on the Discourse of the British Prime Minister’s “Brexit” Political Speech

: Commitment speech acts play an important role in various fields, but compared to other speech acts, they have not yet received sufficient attention. In political discourse, the implementation frequency of commitment speech acts is quite high, while their usage characteristics, pragmatic strategies, and the influence of social domain factors still need to be explored. The correct implementation of commitment speech acts is helpful to achieve the purpose of communication and promote the success of communication. Therefore, based on Talmy’s force-dynamic theory, this paper collects relevant language materials of commitment speech acts contained in British Prime Minister’s “Brexit” political speech discourse, attempts to consider pragmatic factors on the basis of the force-dynamics model to construct force dynamics models about commitment speech acts for analysis. By analyzing the working mechanism between internal and external parameters in force dynamic schema under different promise strategies, this paper explores the action mode of “illocutionary force” in speech acts of commitment and the implementation path of commissives under the influence of social domain factors and other factors. This paper interprets commitment speech act from the cognitive perspective, expecting to broaden the research paradigm of commitment speech acts and provide ideas for future multi-dimensional study on speech act theory.


Introduction
Since Austin's speech act theory was put forward in 1962, scholars have paid much attention to it, and studies on speech acts have emerged one after another.Austin (1962:151-164) divides illocutionary acts in speech acts into five categories, including verdictives, exercitives, commissives, expositives and behabitives.Compared with other speech acts, scholars have not discussed commissives much.However, in political speeches, commitment speech acts are frequently used and have a significant impact on speech effects.Therefore, commissives in political discourse remain to be studied.Searle (1979) argues that commissives are a kind of speech acts of promising, which means that the speaker promises to the listener that he or she will do something in the future.In order to achieve the effect of commitment and realize the purpose of communication, the speaker will inevitably adopt some strategies when implementing speech acts of promising.These strategies play different roles in specific pragmatic situations and have a great influence on the effectiveness of commitment speech acts.
With the development of cognitive linguistics, scholars begin to interpret commitment speech acts from a cognitive perspective.Pérez (2001) describes the ideal cognitive model of commissives, which is mainly carried out in the scope of matters within commitment speech act elements.This study broadens the research angle of commitment speech acts, but does not mention the influence of social domain factors . Li Jianxue (2006) takes the American president's inaugural speech as an example to analyze and discuss the formation, form and characteristics of the hypothetical space constituted by the conditional structure guided by "if" in the discourse of commitment, thus verifying the role of internalization of sociocultural meaning in the implementation of speech acts.As a kind of pragmatic acts in daily communication, speech acts are affected by various internal and external factors, so it is necessary to fully consider the forces of all aspects to interpret the implementation process of speech act.Thus, there are quite a few scholars pay attention to the role of "illocutionary force" in speech acts.Johnson (1987) analyzes the illocutionary force of speech acts based on the force gestalt theory, but did not explain its effect on the listener.Marmaridou (2000) tries to explain such a pragmatic phenomenon as speech act with the theory of cognitive linguistics, but did not form a unified research framework.Mo Qiyang and Duan Yun (2012) builds the illocutionary force-dynamics model based on Talmy's (2000) forcedynamics model to provide an effective way to solve the problems existing in the classical speech act theory.All the above studies have shown that it is feasible and necessary to study speech acts from the perspective of cognition.However, most of the current studies have discussed the illocutionary act of speech act, and have not yet deeply discussed the perlocutionary act, nor have they fully considered the effects of the communication parties and various internal and external factors on speech act itself.
Based on the background, this paper collects the relevant language materials of commitment speech act in the British Prime Minister's "Brexit" political speech and uses Talmy's force dynamic theory to establish force dynamic models of commitment speech acts.Then it discusses the usage characteristics, pragmatic strategies and the influence of social domain factors of commitment speech acts in political discourse, and attempts to explain the ways to realize commitment speech acts from a cognitive perspective, which is expected to broaden the research paradigm of commitment speech acts and strengthen the combination of pragmatics, sociolinguistics and cognitive linguistics.

Talmy's Force Dynamic Theory
The theory of force dynamics was proposed by the cognitive linguist Talmy in 1981.It was initially a generalization of the traditional concept of causality.Later, Talmy gradually improved this theory and put it into the larger category of cognitive semantics.This theory has received extensive attention in the field of cognitive linguistics."Force dynamics" is not only suitable for explaining the interaction of forces between real physical objects, but also extends to the expression of psychological forces through the role of metaphor, and also plays an important role in the representation of social forces.The interaction of forces in the psychological field only involves the psychological activities within the spirit of a single perceiving subject, while the interaction of forces in the social field is the interaction of psychological forces between two perceiving subjects, which is much more complicated (Talmy, 2000:438) .
Talmy's force dynamics theory (2000) contains two core concepts, one is "Agonist", also known as force bearing entity, and the other is "Antagonist", also known as force applying entity, which are two interacting force entities.Besides, the theory has four pairs of parameters: (1) Force entity: "Agonist" and "Antagonist"; (2) Intrinsic force tendency: toward action and toward rest; (3) Balance of strengths: stronger and weaker forces; (4) Resultant: action or rest.The main idea of force dynamic theory is that the effect of language use is the result of the interaction between two forces.Under the influence of the above four pairs of parameters, the interaction between the two force entities will have the following two results: first, the weaker intrinsic force tendency of Agonist will change under the influence of the stronger intrinsic force tendency of Antagonist; second, stronger intrinsic force tendency of Agonist will not be affected by the weaker intrinsic force tendency of Antagonist.Talmy (2000) believes that these parameters and their interactions could be characterized by language, so he analyzes them, and summarizes four basic force dynamic models, namely, the basic constant force dynamic model.The force dynamic system commonly exists in different fields such as the physical domain, psychological domain, and social domain.It is an important basic conceptual organization category, which can be used to interpret the interaction between two force entities.Thus, the theory of force dynamics has been widely applied in linguistic research, and many scholars have already used it as a theoretical framework to study different types of speech acts.For example, Lian Bing (2013) and Cui Linlin (2018) respectively explored the production process and politeness level of request speech acts from the perspective of force dynamics.Wu Shuqiong (2019), Li Shui (2021), and Hu Jialing (2022) respectively conducted force dynamics studies on prohibition speech acts in legislative texts, consolation speech acts, and conflicting speech acts.These studies have confirmed the powerful explanatory power of force dynamics theory on speech acts.Therefore, this article explores commitment speech acts based on the theory of force dynamics, in order to broaden the research paradigm of commitment speech acts and provide richer examples for the application value of force dynamics theory.

Talmy's Force Dynamics Models
Talmy's theory of force dynamics mainly includes three models: the basic constant force dynamic model, the variable force dynamic model, and the sub-constant force dynamic model.This article mainly discusses the first two force dynamic models, so this section only outlines the relevant content of the basic constant force dynamic model and the variable force dynamic model.
1) Basic Constant Force Dynamic Model In Figure 1, the circle shape represents Agonist, and the crescent shape represents Antagonist; "＞" indicates that the intrinsic force tendency toward action, and "•" indicates that the intrinsic force tendency toward rest; Which graphic "+" is in indicates that this entity represented by the graphic has stronger strength; " ＞ " on the horizontal line below the graphics indicate that after the interaction of two forces, the final state of Agonist is action, while "•" represent the final state of Agonist is rest.Based on this, the basic constant force dynamic model can be interpreted as: ( a.) Agonist's intrinsic force tendency in this model toward rest but it has a weaker strength itself.The final state of Agonist changes to action under the stronger strength interaction with Antagonist; ( b.) Agonist's intrinsic force tendency in this model toward rest and it has a stronger strength itself.The final state of Agonist remains rest under the weaker strength interaction with Antagonist; ( c.) Agonist's intrinsic force tendency in this model toward action and it has a stronger strength itself.The final state of Agonist remains action under the weaker strength interaction with Antagonist; ( d.) Agonist's intrinsic force tendency in this model toward action but it has a weaker strength itself.The final state of Agonist changes to rest under the stronger strength interaction with Antagonist; According to this, in the basic constant force dynamic model, the results of the interaction between the two force entities can be summarized as follows: the state of Agonist in ( a.) and ( d.) models changes because its force is less than Antagonist's; the state of Agonist in ( b.) and ( c.) models remains unchanged because its force is greater than Antagonist's.
2) Variable Force Dynamic Model The variable force dynamic model is developed on the basis of the basic constant force dynamic model.Because Antagonist sometimes does not continuously exert constant force on Agonist, the basic constant force dynamic model sometimes changes due to the change of Antagonist's force.
In Figure 2, the arrow pointing inward and outward toward the crescent graphic indicates that a certain force is suddenly applied to Antagonist and that the force of Antagonist suddenly disappears; The slash on the horizontal line below the graphics indicates the change of the state of Agonist.Based on this, the variable force dynamic model can be interpreted as: ( e.) Agonist in this model is in a rest state, and its state changes to action because a certain force is suddenly applied to Antagonist; ( f.) Agonist in this model is in a action state, and its state changes to rest because a certain force is suddenly applied to Antagonist; ( g.) Agonist in this model is in a rest state, and its state changes to action because the force of Antagonist suddenly disappears; ( h.) Agonist in this model is in a action state, and its state changes to rest because the force of Antagonist suddenly disappears; According to this, in the variable dynamic model, the result of interaction between two force entities can be summarized as follow: Antagonist is suddenly impacted by some external force or the force of Antagonist disappears suddenly, and both of the two situations will lead to the change of Agonist's state.

Analysis of Commitment Speech
Acts Based on Force Dynamics Theory

Commitment Speech Acts and Force Dynamics Theory
Commitment speech act means that the speaker sincerely promises to the hearer that he or she will do some behavior in the future, and the hearer believes that he or she will perform the promised behavior based on the trust in the speaker.The promisor's implementation of this act aims to influence some of the promisee's acts.However, because the promisee has an original psychological tendency, that is, to believe or not to believe.There is a potential power confrontation between the promisor and the promisee as two power entities.Among them, the promisor is Antagonist, and the promisee is Agonist.Obviously, according to the force dynamic theory, the speech act of promising contains four pairs of parameters, including the intrinsic force tendency of the speaker and the hearer, balance of strengths between them, the strength difference and the change of the hearer's state.Therefore, there is a oneto-one correspondence between force dynamics and commitment speech acts, and the corresponding relationship can be shown as the table below: It can be seen from Table 1 that the study of the speech act of commitment is essentially an investigation of the interaction between the two entities of the promisor and the promisee.When implementing commitment speech acts, the two forces interact with each other, and the promisee changes the state (including psychological emotion, attitude, behavior, etc.) due to the speech act of the promisor so as to promisor achieve the desired purpose of the implementation of commitment speech acts of the promisor, which is the perlocutionary act of commitment speech acts.
In political speeches, in order to achieve the purpose of commitment, the promisor will adopt different promise strategies according to different audiences and specific situations.The use of promise strategies will directly affect the effect of commitment speech acts, so they should be considered as a force that affects the interaction of force entities.Therefore, in the force dynamic model of commitment speech acts, the factors that affect the illocutionary force of the promisor are not only the factors that affect the illocutionary force proposed by Mo Qiyang and Duan Yun (2012): the speaker's intention and socio-cultural factors (social status, public psychological trends, interests, emotions, etc.) but also the promise strategy.

Force Dynamic Analysis of Commitment
Speech Acts

1) Commitment Speech Acts in Political Speeches
Du Xuhan and Liu Fengguang (2020) found that in ten British Prime Minister's brexit political texts, commitment speech acts accounted for the most in the sample and were used most frequently in the annotation of speech acts.This shows that the British prime ministers have made a lot of political commitments to win the support of the people in their speeches on "Brexit".So, how do these commitment speech acts achieve the effect of commitment?Then, based on Talmy's force dynamics theory, this paper will construct force dynamic models of commitment speech acts, make a qualitative analysis of the language materials containing commitment speech acts in the British Prime Minister's "Brexit" political speeches, explore the usage characteristics, pragmatic strategies and the influence of social domain factors of commitment speech acts in political discourse, and interpret the realization ways of commitment speech act from a cognitive perspective.
2) Classification of Commitment Speech Acts Austin (1962) classified illocutionary acts into five major categories and listed relevant illocutionary verbs.Among them, the illocutionary verbs of commissives include promise, undertake, swear, bet, etc. Verbs in speech acts play a significant role in distinguishing and categorizing speech acts, but Searle (1969) opposed equating the classification of speech acts with the classification of speech act verbs.Zhang Shaojie (1994) pointed out that this is because the meaning of verbs is often difficult to distinguish, and the speaker's communicative intention is not always very clear.The use of language has different pragmatic meanings in different contexts.Therefore, Searle proposed the indirect speech act theory.Indirect speech act refers to the indirect implementation of an illocutionary force through another speech act.At the same time, Searle also classified indirect speech acts into conventional indirect speech acts and nonconventional indirect speech acts.According to the direct degree of the expression of commitment speech acts, this paper divides the speech act of promising into direct commitment and indirect commitment, in which the indirect commitment includes the conventional indirect commitment and the non-conventional indirect commitment. 3

) Force Dynamic Models of Commitment Speech Acts in Political Speeches
In political speech discourse, in order to achieve the effect of commitment and the purpose of speech, the implementation of commitment speech acts usually includes the separate or combined use of direct commitment, conventional indirect commitment and non-conventional indirect commitment, and the effectiveness of commitment speech acts is often enhanced through the rational use of various promise strategies.Therefore, this section will discuss the use and effect of different types of commitments in the "Brexit" speeches of the British Prime Minister, the pragmatic strategies chosen by the promisor when implementing the commitment speech act, and the influence of factors such as social domain on the choice of commitment methods.By constructing force dynamic models, this paper provides a schematic explanation for explaining the mechanism of "illocutionary force" in commitment speech acts and the way to realize the commitment speech acts.
(1) Force Dynamic Models of Direct Commitment Direct commitment is often accompanied by an obvious marker, which is the core commitment, and is generally undertaken by the illocutionary verb of commitment.Therefore, direct commitment refers to a type of commitment that can be easily identified from the perspective of discourse form.Direct commitment mostly refers to that the promisor takes the first person as the subject of the illocutionary act and promises to the promisee that he or she will do something to gain the support or trust of the promisee.Generally, the promise strategy of misgiving relief and the promise strategy of fact guarantee are used in direct commitment.
Example 1: I would also reassure Britons living in European countries and European citizens living here there will be no immediate changes in your circumstances.(我也 向居住在欧洲国家的英国公民以及在英国居住的欧洲公 民保证，你们的现状不会立刻发生改变。 ) Example 2: And it's why I made the pledge to renegotiate Britain's position in the European Union and to hold the referendum on our membership and have carried those things out.(这也是为什么我做出承诺，与欧盟重新商议英国的 地位、开启英国与欧盟关系的公投，并实现它们。 ) These are direct commitments made by David Cameron to the public in his speech on June 24, 2016, using the illocutionary verbs "promise" and "pledge".Such as example 1, he assures the people of their vital interests by using the promise strategy of misgiving relief to gain the trust of the people.In example 2, Cameron uses the fact guarantee commitment strategy to enhance the illocutionary force of his commitment speech acts by using the credibility guarantee of his completed commitment, so as to enhance the credibility of his current commitment.He made a commitment to the people again based on the fact that he directly expressed that he had made and realized his commitment.In this direct commitment, the fact conforms to the psychological needs of the people, and the credibility of the commitment will be further improved.The force dynamic models of Example 1 and Example 2 are as follows: From the corresponding relationship between force dynamics and commitment speech acts in Section 1 of Chapter 3, it can be known that in the force dynamic model of commitment speech acts, the circle graphic represents the promisee, and the box graphic represents the promisor; "＞" indicates that the intrinsic force tendency toward trust, "•" indicates that the intrinsic force tendency toward not trust; Which graphic "+" is in indicates that this entity represented by the graphic has stronger strength, and the arrow pointing inward and outward toward the box graphic indicates that a certain force is suddenly applied to Antagonist and that the force of Antagonist suddenly disappears; The slash on the horizontal line below the graphics indicates the change of the state of Agonist.
By observing the force dynamic model of Example 1 in Figure 3, it can be found that this model belongs to the deformation of one of the Talmy's variable force dynamic model (( g.) in Figure 2).In the force dynamic model of Example 1, the promisee tended to be willing to trust, but the objective or subjective misgivings made it in an initial state of distrust, while the illocutionary force of the promisor through direct promising removed the obstacles of misgiving by using the promise strategy of misgiving relief, so that the promised person's state changed: from not trust to trust.In the force dynamic model of Example 1, the promisor uses the promise strategy of fact guarantee to enhance the illocutionary force of the the promisor, which is greater than that of the promisee, and finally makes the state of the promisee from not trust to trust.
(2) Force Dynamic Model of Conventional Indirect Commitment He Zhaoxiong (2000:101) pointed out that the conventional indirect commitment means that the speaker makes the hearer clearly infer the meaning of the promise by means of the convention or some contextual premises, and is willing to implement what the speaker promises to do.The hearer can understand the commitment of the promisor's intention with a little derivation.Therefore, this type of commitment must be used when both parties can understand a conventional language form (prescriptive deixis).In political speeches, the promisor usually uses the empathetic promise strategy to strengthen the illocutionary force of conventional indirect commitment.
Example 3: And I and we will never take your support for granted.And I will make it my mission to work night and day, flat out to prove you right in voting for me this time and to earn your support in the future.(我和保守党永远不会认为 你们的支持是理所当然的。我将以夜以继日地工作为己 任，竭尽全力证明，你们这次投票给我是正确的，并在未 来赢得你们的支持。 ) Example 4: And whatever the bumps in the road ahead, I know that we will succeed.(无论前方的道路多么坎坷， 我都知道，我们会成功的。 ) These two examples are taken from Boris Johnson's victory speech on December 13, 2019 and his speech to the public one hour before the official Brexit of the UK on January 31, 2020.In both examples, he used the conventional commitment verb "will" to make an indirect commitment, where "will" is used as a modal verb to express his will in a positive or negative sentence.In Example 3, Johnson made it clear that he and the Conservative Party would not take the support of the people for granted, so as to narrow the distance with the people and reduce the promisee's intrinsic force tendency of "distrust" , so as to weaken the strength confrontation between the promisor and the promisee.He then expressed that he would work around the clock and indirectly promised that he would live up to the support of the people.In Example 4, Johnson used "we" as the action performer to establish a community of shared future for himself and the people.Through empathy and understanding the wishes of the people, he promised to work with the people, fight side by side with the people, win the victory after Brexit, so as to enhance the illocutionary force of commitment speech acts.In addition, while maintaining and enhancing his reputation, he also shaped the image of a responsible leader and maintained the authority as the British Prime Minister.The force dynamic model of examples 3 and 4 is as follow: In Figure 4, the graphic in the middle of the two force entities indicates the shortening of the psychological distance between the two subjects.As in Examples 3 and 4, the promisor adopted the empathetic promise strategy, which actively narrowed the distance between the two entities.By removing part of the promisee's strength, reduces the strength of the promised person's intrinsic force tendency, so that the reaction force of Agonist was reduced.Finally, under under the stronger strength interaction with the promisor, the state of the promisee changed from distrust to trust.
(3) Force Dynamic Models of Non-Conventional Indirect Commitment Non-conventional indirect commitment means that the intention of the promisor is not explicitly reflected in the language form, and requires inference based on the context and shared knowledge information of both parties.The prescriptive deixis of this type of commitment are not highly explicit, and a combination of multiple commitment strategies is usually used to achieve communicative purposes, resulting in more diverse sentence structures.
Example 5: And while we are not perfect I do believe we can be a model for the multi-racial, multi-faith democracy, that people can come and make a contribution and rise to the very highest that their talent allows.(虽然我们并不完美， 但我相信我们能成为多种族、多信仰的民主的典范。人们 可以来到英国做出贡献并凭借才华能力达到自己的顶 峰。 ) Example 6: I understand all those feelings, and our job as the government-my job-is to bring this country together now and take us forward.(我理解所有这些感受，我们作 为政府的工作--也是我的工作，就是团结整个国家，并 带领我们前行。 ) These two cases were taken from the speeches of Cameron and Johnson respectively, and both of which used a variety of commitment means to achieve non-conventional indirect commitments.In Example 5, Cameron successfully made non-conventional indirect commitments by expressing his belief that Britain can become a model of multi-racial and multi-faith democracy, activating the existing image of Britain in the hearts of the people to improve the illocutionary force of non-conventional indirect commitments.Then he used the promise strategy of fact guarantee to encourage people to come to the UK to make contributions and realize their own life value.In Example 6, Johnson used the empathetic promise strategy to not only connect himself with the feelings of the public, but also connect himself with the government to strengthen the illocutionary force of nonconventional indirect commitments.Using the purpose adverbial as a non-prescriptive means to enhance the credibility of the discourse context in the hearts of the promisees, ultimately making an perfect non-prescriptive indirect promise.The force dynamic models of Example 5 and Example 6 are as follows: Observing the force dynamic model of Example 5, it can be found that Agonist is suddenly applied with a certain force.
Using the non-conventional commitment means, the promisor activated another intrinsic force tendency of the promisee, and this force counters the original intrinsic force tendency, so that the illocutionary force of the promisor's nonconventional commitment has been further improved.In addition, the strength of Antagonist itself is relatively strong, the promisee's state finally has changed semi-actively and semi-passively: from not trust to trust.Example 6: Influenced by the use of non-conventional means of deixis, the intrinsic force tendency of the promisee itself is also changed, and coupled with the use of the empathetic promise strategies, the ultimate state of the promisee becomes trust.4) Effectiveness Analysis of Commitment Speech Acts under the Dynamic Force Model By interpreting the force dynamic model of commitment speech acts in political discourse, we can find that: first, in terms of the strength of the illocutionary force of commitment, direct commitments directly conveys the illocutionary force to the promised person through the core commitment words, which has the strongest commitment illocutionary force; With the help of social prescriptive directive means, the conventional indirect commitment conveys illocutionary force, which requires the promised person has a certain understanding of the context,so it has medium commitment illocutionary force; The non-conventional indirect commitment needs to rely on the context and the common knowledge and information of both parties to infer the illocutionary force.It has high requirements for the understanding ability of the promised person, and has the least commitment force.However, with the help of promise strategies, the promisor still can achieve good commitment effects and achieve certain communicative goals.We can see that the effectiveness of commitment speech acts is improved through the combined effect of commitment illocutionary force and promise strategies, which is the basis of the correct implementation of commitment speech acts.Secondly, in terms of the choice of the commitment perspective of the promisor, most promises in political speeches use the first person as the agent subject.But compared to making a commitment as a single promisor, using the empathetic promise strategy to connect with the promised person to make a commitment will result in better commitment effectiveness.

Conclusion
By combining the force dynamic theory and commitment speech acts, this study constructs dynamic models of the speech act of promising in political discourse, and makes a cognitive interpretation of the ways to realize it.The findings are as follows: First, besides the speaker's intention and socio-cultural factors, there are also promise strategies that affect commitment's illocutionary force; Secondly, the effectiveness of commitment speech acts is affected by the above factors' combined action.The illocutionary force of commitment is strengthened by the appropriate choice of promise strategy, and commitment speech acts achieves good commitment effect under the joint action of the illocutionary force of commitment and commitment strategies; Thirdly, pragmatic strategies for commitment include the promise strategies of misgiving relief, the promise strategies of fact guarantee, and the empathetic promise strategy.The selection and use of these strategies are influenced by social domain factors, which include social, cultural, and psychological factors.At last, this study broadens the research paradigm of commitment speech acts, and provides ideas for the multidimensional research of commitment speech acta in the future.At the same time, it widens the application scope of force dynamic theory and provides richer examples for the explanatory power of this theory.However, due to the lack of language materials and the immature theoretical framework, this study only conducted a preliminary exploration.The later research can further enrich the language materials and apply the theory to the analysis of commitment speech acts in other political texts or texts in different fields.

Figure 3 .
Figure 3.The left side: Example 1; The right side: Example 2

Figure 5 .
Figure 5.The left side: Example 5; The right side: Example 6

Table 1 .
The Corresponding Relationship Between Force Dynamics and Commitment Speech Acts