29 Leadership Theories
Prof. Geeta Bansal
1. Module 1:Theories of leadership
2. Learning Outcome
4. Early Trait Theories
5. Behavioral Theories
5.1 Lewin’s Leadership Styles
5.2 Ohio State Studies
5.3 Michigan Studies
5.4 Leadership Grid : A Contemporary Extension
6. Contingency Theories
7. Recent Leadership Theories
7.1 Leader Member Exchange Theory
7.2 Inspirational Leadership
7.2.1 Transformational leadership
7.2.2 Charismatic leadership
7.2.3 Authentic leadership
8. Summary
2. LEARNING OUTCOME
- After going through the lesson you should be able to :
- Understand the research and the theoretical framework underlying the various theories of leadership.
- Find out which theories of leadership are more valid in today’s context.
- Make a comparative analysis of the trait theories, behavioral theories contingency theories and some recent theories of leadership and their implications.
3. INTRODUCTION
”Leadership is defined as the act or process of influencing people as that they will strive willingly and enthusiastically towards the achievement of group goals”.
The Importance of Leadership lies in Motivating, Creating confidence and Building up the morale its people. Different authorities and researchers have viewed leadership differently. Some put emphasis on personal options, while others view leadership as situational. The research conducted by behavioral scientists to find out as to what makes a leader effective have resulted in various “theories of leadership” which are discussed in the following pages.
4. TRAIT THEORIES
Thomas Carlyle was a precursor of the trait theory which tried to find out what physical traits, personality traits and personal abilities differentiates leaders from non leaders.
The Physical Traits are the genetic makeup of the person comprising his height weight complexion, age, stamina etc. research does not prove that physical traits have anything to do with leadership.
The Personality Traits would be creativity, adaptability, dominance self confidence, integrity, emotional intelligence etc. some evidence has shown that leaders are more adaptable self confident and emotionally intelligent than non leaders.
The Personal Abilities include social skills, communication skills, intelligence cooperativeness etc.
again research has shown a positive relation between a person’s abilities and his leadership skills.
In spite of all the research, it has not been validated that trait theory is valid for measuring leadership qualities.
5. BEHAVIOURAL THEORIES
5.1 Lewin’s Leadership Styles
5.2 Ohio State Studies
5.3 Michigan Studies
5.4 Leadership Grid : A Contemporary Extension
The Behavioural Theories are Based on the assumption that leaders can be made if specific behaviours are identified and are taught….
The inability of the trait approach to consistently define specific traits that would differentiate successful and unsuccessful leaders led to the conclusion that emphasis on the behaviour of leaders (which could be measured) rather than emphasis on traits (which could not be measured) were an appropriate new research strategy. According to this theory, a particular behaviour of a leader provides greater satisfaction to the followers and so they recognize him as a good leader. Moreover trait theories did not address how leaders behaved.
The three theories which have laid down the foundation of many modern theories have been given by Lewin, Lippit and white, the Ohio State studies and of Michigan studies .
5.1 Lewin’s Leadership Styles
Kurt lewin and his students outlined three basic leadership styles ;Autocratic , democratic and laissez faire leadership styles. They said that every leader has a peculiar style which is not situation specific but is leader specific.
An Autocratic Leader usually follows strict rules and regulations and controls the work environment where the followers do not have much discretion but to follow his instructions.
While The Democratic Leader is collaborative cooperative , responsive and believes in taking decisions with the followers consensus unlike the autocratic leader.
The Laissez Faire Leader believes in non leadership, he does not use his authority and responsibility which often leads to role ambiguity on the part of both the leaders and the followers leading to conflicting situations at the workplace.
5.2 Ohio State Studies
The research conducted at the Ohio state university aimed at measuring specific leadership behaviors; specifically it was to ;
Identify the behaviors exhibited by leaders.
Determine what affect these behaviors had on employee satisfaction and performance. Identify the best leadership style.
The preliminary results showed that there are two significant behavioral dimensions namely the initiating structure and the consideration.
The Initiating-structure Behavior defines the roles of leader and follower so that everyone knows what is expected. This includes establishing formal lines of communication and deciding how tasks are to be performed.
The Consideration Behavior aims at having a nurturing and a friendly work environment based on mutual trust .
5.3 The Michigan Studies
The Michigan studies found out that the leadership behavior has important implications on the followers contribution to the organization and their emotional well being. Here two styles of leadership were identified namely; employee oriented and the production oriented.
The employee oriented style believes in harnessing congenial relationships at the workplace. The workplace is not reeling under the pressure of too many written rules and regulations and the leader exhibits considerable concern for the employees needs and aspirations at the workplace.
While the production oriented style is characterized by getting things done through close supervision, lots of written rules and regulations to control the employees behavior unlike the employee oriented style.
5.4 Leadership Grid : A Contemporary Extension
Robert R Blake and Jane S Moulton have designed an organization development program emphasizing the importance of the two basic leader behaviours (concern for people and concern for production) originally identified in the Ohio State and Michigan studies. However, rather than viewing each type of concern as an absolute measure, the leadership grid puts them into continuums. A leader thus has low to high concern for people and low to high concern for production. Each type of concern is ranked on a scale from 1 to 9, resulting in five managerial styles. Further investigation into the grid has led to the outcome of two more leadership styles , resulting in seven major combinations of leader behavior. See figure 1.
Figure 1 : The Managerial Grid:
1. Impoverished Management (1,1): Here the leader will exert just enough effort to sustain by. He shows Minimal concern for
production or people thereby resulting in the minimum contribution from the employees.
2. Authority-Compliance Management (9,1): Here the leader emphasizes on having efficient production through high
concern for production and low concern for people resulting in maximum contribution of the employees.
3. Country Club Management (1, 9): Here the leader aims at creating a comfortable and a friendly workplace environment
with Low concern for production and high concern for people, resulting in a comfortable conflict free working environment.
4. Organization – Man Management (5, 5): Here the leader shows moderate levels of concern for both people and
production, resulting in adequate performance of the employees.
5. Team Management (9, 9): Here the leader shows High levels of concern for both people and production, resulting in the
creation of a highly productive and committed team of employees.
6. Paternalistic management (9+9): Here the leader shows promises for reward for good performance and does not hesitate
in reprimanding or punishing for poor performance just like a father figure.
7. Opportunistic management (1,1) (9,1) (1,9) (5,5) (9, 9) (9+9) : here the manager applies the style which returns him the maximum self benefits
The model is designed to help managers first see their current leadership style and then to help them develop the most desirable style. Blake and Mouton believe there is an ideal style 9, 9 management. This grid has been used for team building and leadership training in organization’s OD interventions. However, they have found that most managers use the middle-of the road style of leading by showing medium concern for employees and production.
6. CONTINGENCY THEORIES
6.1 Fiedler’s Contingency Theory
6.2 Robert House’s Path Goal Theory
6.3 Vroom Yetton And Jago’s Normative Decision Theory
6.4 Hersey And Blanchard’s Situational Leadership Model
Contingency theories of leadership focus on particular variables related to the environment that might determine which particular style of leadership is best suited for the situation. According to this theory, no leadership style is best in all situations. Success depends upon a number of variables, including the leadership style, qualities of the followers, and aspects of the situation.
There are many forms of contingency theory. In a general sense, contingency theories are a class of behavioral theory that contends that there is no one best way of organizing / leading and that an organizational/leadership style that is effective in some situations may not be successful in others. In other words:
Four important ideas underlying the Contingency Theory are that :
I. There is no universal or one best way to manage or lead the teams,
2. The design of an organization and its subsystems must ‘fit’ with the environment,
3. The needs of an organization are better satisfied when it is properly – designed .
4. The management style is appropriate both to the tasks undertaken’ and the nature of the work group.
6.1 Fiedler’s Contingency Theory
Fred Fiedler’s contingency model focused on individual leadership. The situational contingency theory proposes that the effectiveness of a leader is determined by two factors
1. The leaders’ need gratification .
2. The Favorableness of the leader’s situation, the degree to which the leadership situation provides the leader with control and influence over the outcomes.
The theory assumes that the leaders are either Task-oriented or relationship oriented depending upon what satisfies their primary need gratification.
1. The needs of the task oriented leaders are fulfilled with the achievement of the desired tasks while the relationship
oriented leaders needs are satisfied by developing and nurturing good interpersonal relations at the workplace.
2. Now their success would depend upon the favorableness of the situation.
3. The favorableness of the situation is again dependent upon leader’s position power, the structure of the teams task and
the quality of relationship between the leaders and the followers.
These three conditions are explained below ;
1. The Least Preferred Coworker,
2. Situational Favorableness and
3. Leadership effectiveness
1.The Least Preferred Coworker
This theory aims at finding out whether the leader is task oriented or relationship oriented through the
Least Preferred Coworker scale ( LPC ) which aims at identifying the workers with whom the leader
least prefers to work with. this is a scale comprising of sixteen eight point bipolar adjective sets. e.g
Obedient ::::::::: disobedient
Efficient :::::::::: inefficient
Fun loving :::::::::: gloomy
The leaders who gives good scores to their coworkers ( pleasant, efficient , happy fun loving etc. ) are more inclined towards building good interpersonal relations and are hence termed as high LPC or relationship oriented leaders.
While the leaders who give negative scores to their coworkers (unpleasant, inefficient , gloomy etc. ) are more inclined towards completing their tasks are termed as low LPC or task oriented leaders. Though this LPC score has not found much acceptability due its poor measurement reliability .
2.Situational Favorableness
The favorableness or un favorableness of the situation would depend upon three dimensions.
1. The task structure: i.e. how clearly the rules and regulations are laid down.
2. The position power: the legitimacy of the leaders authority to reward and punish
3. Leader member relations: this is measured by the general atmosphere at the workplace, whether it is friendly or unfriendly with healthy relationships or is mired by conflicts.
The favorable leadership situation will have structured tasks, strong leader position with legitimate power and congenial relationships between the leader and the workers and vice versa.
3. Leadership effectiveness
According to Fiedler’s contingency theory , the task oriented leaders (With low LPC score) and relationship oriented leaders ( with high LPC score ) will be effective only when they are in the right situation. Where the task oriented leaders will be effective in either very favorable or very unfavorable leadership situations. The relationship oriented leaders are effective in situations of intermediate favorableness, moreover, Research has shown that they encourage a lot of innovation and creativity which enables them to capture the market faster than the task oriented leaders.
6.2 Robert House’s Path Goal Theory
Developed by Robert House, the Path Goal theory is one of the most respected approaches to leadership. The essence of the theory is that it’s the leader’s job to assist his or her followers in attaining their goals and to provide the necessary direction and support to ensure their goals are compatible with the overall objectives of the group or organization. According to this theory, leaders attempt to influence their subordinate’s perceptions of the pay off or accomplishing their goals and show them ways to achieve the goals. Thus, a leader’s behavior is motivational, to the degree it;
(i) Makes subordinate need satisfaction contingent on effective performance, and
(ii) Provide the coaching, guidance, support and rewards that are necessary for effective performance.
House suggests that the leader should make desired rewards available (goal) and clarify for the subordinate the kinds of behavior that will lead to the reward (path).
The theory proposes four types of leader behavior and two situational variables
To test these statements, House identified four leadership behaviours or styles:
(i) Directive Style: The leader tells subordinates what is expected of them and gives them guidance about what-should be
done and also shows them how to do it
(ii) Supportive Style: The leader shows concern for the well-being and needs of his or her subordinates by being friendly and
approachable.
(iii) Participative Style: The leader involves subordinate in decision making consults with them about their views of the
situation, asks for their suggestions considers those suggestions in making a decision, and sometimes lets the subordinates
make the decision themselves.
(iv) Achievement-Oriented Style: The leader helps subordinates set goals, reward the accomplishment of these goals and
encourages subordinates to assume responsibility for their attainment.
The two situational variables are:
1. Subordinate characteristics– which includes ability (for esteem and self-actualization) and personality traits (authoritarianism, close-mindedness).
2. Task characteristics– which includes, simple versus difficult, stressful versus non-stressful, dull versus interesting, and safe versus dangerous tasks.
House assumes that leaders are flexible and implies that the same leader can display any or all of these behaviours, depending on the situation.
Applying Path-Goal Theory
The leader will begin be choosing a leadership style that fits the situation. To do this, the leader has to assess five aspects of the situation and people involved:
(i) Assess the Task: Structured tasks and clear goals/require less direction then less structured tasks and less clear goals.
(ii) Assess the Nature of the Work Group: The leader should assess its cohesiveness as well as its experience in working together. The more cohesive the group, the less need for supportive leadership since this is redundant with the group’s character.
(iii) Assess the Organization Culture: A culture that supports participation also supports a participative leadership style. A culture that encourages goal accomplishment or a results orientation- reinforces an achievement-oriented;’ style.
(iv) Assess the Subordinate’s Skills and Needs: Subordinates skilled in a task require less direction than those less skilled.’ Subordinates with high achievement needs, require a style that helps meet these needs. Subordinates with social needs, require a style that helps meet these needs.
However, there is limitation to this theory, but there are some implications for leaders/managers.
It is more flexible than Fiedler’s theory in that it proposes that a manager uses different types of behaviors in different situations. Moreover, a leader can enhance performance by either increasing the rewards or making the paths toward rewards easier to travel.
6.3Vroom Yetton Jago’s Normative decision making Theory
The normative theory offers guidelines on how decisions ought to be made in specific situations. Five decision-making stages ranging from highly autocratic to highly participative are identified. The appropriate method depends on the answer to seven questions relating to the problem being solved and subordinates involved. The first three protects the quality of the decision and final four enhance the subordinate acceptance. This theory is attractive because it provides precise answers for dealing with the question of subordinate participation. The theory is useful to managers because it suggests that a leader may need to be autocratic in one situation and consultative in the next.
This is a leader-participation model that related leadership behavior and participation to decision making. They assume that leaders use four basic styles in making decisions: authoritative, consultative, group-based and delegative. These styles led to different decision-making processes for solving both individual and group problems.
The five styles used in decision making are ;
1. Decide: the manger makes the decision alone and announces it .
2. Consult Individually: the manger takes the individual input of the group members and then take the decision .
3. Consult Group: here the manager presents the problem in front of the whole group collectively and takes the inputs and
then takes the decision
4. Facilitate: here the manager acts as a facilitator only by defining the boundaries for the decision and the group is allowed
to take initiative in decision making.
5. Delegate: here the manger allows and encourages the group to take decisions within prescribed limits.
6.4. Hersey & Blanchard’s Situational Leadership Theory
This theory suggests that the leader’s behavior should be adjusted to the maturity level of its employees. The model uses the same two dimensions of leader behavior’s as propagated by Ohio state studies i.e. one dimension is task oriented Behavior and the other is relationship oriented Behavior, which is decided by the maturity level of the followers ( measured by their ability and willingness) .
Thus the framework of H&B is a function of three variables.
1. Task Behavior:
a. Amount of direction demonstrated by the leader.
b. Guidance a leader gives-task behavior.
2. Relationship Behavior:
a. Amount of emotional support demonstrated by the leader.
b. Relations behavior.
3. Maturity Level of the followers
a. Ability of followers on a particular task.
b. Willingness of followers to perform the task-maturely.
The leader will adopt any one style as exhibited below; Telling, Selling , Participating And Delegating depending upon maturity level of the followers. See figure 2.
Figure 2 : Hersey & Blanchard’s four Leadership styles
The Horizontal Axis shows the leader’s concern for task behavior and the Vertical Axis shows the leader’s concern for relationship behavior. It can be seen that the “Mature” followers( having both high ability and willingness ) respond to delegating and participating styles and the “Immature” ( low ability and willingness) followers respond to telling and selling styles.
Telling style is applicable when the leader is followers have low maturity levels, he himself
High task oriented and low relationship oriented and the decides on the course of action and announces it.
Selling style is applicable when the leader is High task oriented and high relationship oriented and the maturity level of the followers is a bit higher , the Leader decides on the course of action and sells it to the followers.
Participating style is applicable when the leader is High relationship oriented and low task oriented and the maturity level of the followers is on the higher side ; Leader involves followers in the decision making process.
Delegating style is applicable when the leader is Low on both relationship and task orientation and the followers exhibit high degree of maturity; Leader allows followers to decide/implement the decisions on their own.
Hersey & Blanchard’s theory provides a useful and understandable framework for situational leadership. The model suggests that there is no one best leadership style for all situations. Manager’s leadership style must be adaptable and flexible to meet the changing needs of employees and situation which calls for
Knowing your style
Matching your style to follower maturity and task situation
Contingency or situational theories differ from the earlier trait and behavioral theories in asserting that no single way of leading works in all situations. Recent research suggests that managers should select a leadership that best fits with the situation at a given time. Effective managers diagnose the situation, identify the leadership style that will be effective, and then determine if they can implement the required style. Early situational research suggested that three general factors affect the appropriate leadership style in a given situation.
(i) Subordinate Considerations: Reflect the leader’s awareness of subordinate’s expertise, experience, competence, job knowledge, hierarchical level and psychological characteristics.
(ii) Supervisor Considerations : Reflect the leader’s degree of upward influence, as well as his or her similarly of attitudes and behaviors to those in higher positions.
(iii) Task Considerations : Reflect the degree of time urgency, amount of physical danger, permissible error rate, presence of stress, degree of autonomy, degree of job scope, importance and meaningfulness, and degree of ambiguity of the work being performed.
The precise aspects of each dimension that influence the most effective leadership style vary in different situations. Most situational theorists suggest that effective leaders develop a range of leadership styles, which they adapt to different situations.
7. RECENT LEADERSHIP THEORIES
7.1 Leader Member Exchange Theory
7.2 Inspirational Leadership
7.2.1Transformational leadership
7.2.2Charismatic leadership
7.2.3Authentic leadership
Some new developments on the leadership front have given rise to the newer theories which are directed towards leader member relations, inspiring leaders who are charismatic authentic and transformational which are discussed below
7.1 Leader Member Exchange Theory
Popularly called the LMX theory maintains that leaders usually form varying relationships with their followers, where some of them become a part of their in group who enjoy more attention and are given higher levels of authority and responsibility than the followers who are in the out group and do not enjoy the attention of the leader. This also determines the citizenship behavior of the followers which is more visible in the members of the in group than the out group.
7.2 Inspirational Leadership
Some new research has shown inclination towards inspirational leadership, which has been identified as Transformational Leadership, charismatic leadership and authentic leadership which are discussed below.
7.2.1 Transactional vs. Transformational Leaderships
According to James Burns there are two types of leaders: transformational and transactional.
Transformational leaders are those who recognize, exploit and satisfy the needs of followers while elevating them into high levels of motivation and morality. Transformational leadership elevates the goals of subordinates and inspires them to give their best to an organization. Transformational leadership, primarily, consists of four dimensions: charisma, Inspirational motivation individualized consideration and intellectual stimulation.
Charisma or individualized influence: Provides vision and sense of mission, instills pride, gains respect trust.
Inspirational motivation: Communicates high expectations, uses symbols to focus efforts, and expresses important purposes in simple ways.
Intellectual Stimulations: Promotes intelligence, rationality, and careful problem solving.
Individualized consideration: Gives personal attention, treats each employee individually, coaches, and advises..
In Transactional leadership, the leader exercises influence during daily leader subordinate exchanges without any special emotional inputs or considerations. The leader offers rewards to subordinates who achieve the tasks assigned to them (or, for showing appropriate behavior). His focus is on achieving results in a practical way, clarifying things to subordinates. He is hardworking, tolerant and fair minded. He generally takes pride in keeping things running smoothly and efficiently. He often emphasizes the importance of impersonal aspects of performance such as plans, schedules and budgets. He has a sense of commitment to the organization and conforms to organizational norms and values.
7.2.2Charismatic leadership
This leadership style is visible when the leader displays exceptional personal abilities, knowledge skills and certain behaviors which gives him an edge over others , and is able to influence the decisions of the groups or individual by the sheer virtue of the combined effect of all the personality traits which distinguishes leaders’ from non leaders which is called charismatic leadership.
The Key Characteristics of Charismatic leaders
1. Self Confidence- They have complete confidence in their judgment and ability.
2. A vision- This is an idealized goal that proposes a future better than the status quo. The greater the disparity between idealized goal and the status quo, the more likely that followers will attribute extraordinary vision to the leader.
3. Ability to articulate the vision- They are able to clarify and state the vision in terms that are understandable to others. This articulation demonstrates an understanding of the followers’ needs and, hence acts as a motivating force.
4. Strong convictions about vision- Charismatic leaders are perceived as being strongly committed, and willing to take on high personal risk, incur high costs, and engage in self-sacrifice to achieve their vision.
5. Behavior that is out of the ordinary- Those with charisma engage in behavior that is perceived as being novel, unconventional, and counter to norms. When successful , these behaviors evoke surprise and admiration in followers.
6. Perceived as being a change agent- Charismatic leaders are perceived as agents of radical change rather than as caretakers of the status quo.
7. Environmental sensitivity- These leaders are able to make realistic assessments of the environmental constraints and resources needed to bring about change.
7.2.3Authentic/ ethical and moral leadership
This type of leadership has been much in demand these days owing to the fall in the ethical standards of the top leadership as witnessed in the various scandals rocking the business world. The Volkswagen scandal being the latest to hit the corporate world. There is an increasing emphasis on the top leadership who hold high moral values and ethics and can lead the organizations without falling prey to the greed of making fast bucks. The ability of the leaders to act in the right way as differentiated from the wrong is called moral quotient.MQ determines the ability to appreciate and understand the difference between Knowing Vs Doing the right thing. It enables you to distinguish the RIGHT from the WRONG. Nevertheless moral competency is making its presence felt on the corporate landscape owing to a powerful correlation between strong moral values and business success. Research also shows that, it is by no accident that the most successful leaders attribute their accomplishments to a combination of business savvy practices and strict adherence to moral code.
The sagas of some of the iconic and legendary organizations like The Enron’s, The Mitsubishis; The Lucent Technologies was still fresh, when the greed of the Lehman brothers and our very own Satyam shook the business world. AND one fine morning, our cricket crazy nation was aghast at the match fixing scandal at the IPL which made everybody raise their eyebrows in astonishment and being betrayed by the few greedy people who took away the sanctity of the game in a few seconds. These are examples of some of the great organizations whose Global identities have been brought to naught, thanks to the fiasco of moral leadership at the top. This bears ample testimony to the freewheeling of the moral compass of its leaders which saw these organizations crashing at the stock markets.
It is in this light that authentic/ ethical leadership is making its presence felt in the leadership literature and research.
8. SUMMARY
The chapter brings to the fold some of the prominent leadership theories , classifying them into trait theories which takes into consideration the physical , the personality and the personal traits of the leaders to differentiate leaders from the non leaders.
The behavioral theories emphasized that there are certain behavioral traits which differentiates the leaders from the non leaders and thereby relies on some of the researches conducted by Lewin, Ohio state and Michigan studies, where Lewin identified three leadership styles, namely autocratic, democratic and Laissez Faire Leader. The preliminary results of the Ohio studies showed that there are two significant behavioral dimensions namely the initiating structure and the consideration.
The Michigan studies found out that the leadership behavior has important implications on the followers contribution to the organization and their emotional well being. Here two styles of leadership were identified namely; employee oriented and the production oriented.
The managerial grid by Robert R Blake and Jane S Moulton emphasizes the importance of the two basic leader behaviors (concern for people and concern for production) originally identified in the Ohio State and Michigan studies resulting in seven major combinations of leader behavior; Impoverished Management ,Authority-Compliance Management , Country Club Management ,Organization – Man Management, Team Management, Paternalistic management and Opportunistic management
The Contingency theories of leadership focus on particular variables related to the environment that might determine which particular style of leadership is best suited for the situation. According to this theory, no leadership style is best in all situations. Success depends upon a number of variables, including the leadership style, qualities of the followers, and aspects of the situation. Four types of contingency theories have been discussed ,Fiedler’s Contingency Theory ,Robert House’s Path Goal Theory, Vroom Yetton And Jogo’s Normative Decision Theory and Hersey And Blanchard’s Situational Leadership Model.
Some new developments on the leadership front have given rise to the newer theories which are directed towards leader member relations, inspiring leaders who are charismatic authentic and transformational which are discussed in the lesson.
Learn More:
- Ashwathappa, Organization Behaviour. Tata McGraw Hill Khanka,S.S, Organizational Behaviour,S.Chand &Co.New Delhi.
- McShane,S.L.,Glinow, M A V.,Sharma,R ,R. Organizational Behaviour, Tata McGraw Hill
- A.G Jagpo and Victor H. Vroom, “Hierarchical Level and leadership style” Organizational Behaviour and Human Performance No. 18 (1977).
- Fred E. Fiedler, “A Theory of Leadership Effectiveness”. McGraw Hill, New York (1967).
- Stephen P. Robbins, Organizational Behaviour, Concepts, Prentice Hall, India
- Gray Desslar, Organization Theories, Prentice Hall, India .
- L.M. Prasad, Management Process and Organizational, Sultan Chand & Sons