Independence of irrelevant alternatives

<p>Independence of irrelevant alternatives (IIA) is an <a href="/facts/Axiom/mLjP14Mc">axiom</a> of <a href="/facts/Decision_theory/TbXcQX0v">decision theory</a> which codifies the intuition that a choice between 
  
    
      
        A
      
    
    {\displaystyle A}
  
 and 
  
    
      
        B
      
    
    {\displaystyle B}
  
 should not depend on the quality of a third, unrelated outcome 
  
    
      
        C
      
    
    {\textstyle C}
  
. There are several different variations of this axiom, which are generally equivalent under mild conditions. As a result of its importance, the axiom has been independently rediscovered in various forms across a wide variety of fields, including <a href="/facts/Economics/HYctA2Dn">economics</a>, <a href="/facts/Cognitive_science/8qoggl7r">cognitive science</a>, <a href="/facts/Social_choice_theory/ztMqy1bM">social choice</a>, <a href="/facts/Fair_division/v4PN6nfD">fair division</a>, <a href="/facts/Decision_theory/TbXcQX0v">rational choice</a>, <a href="/facts/Artificial_intelligence/lJGauQwX">artificial intelligence</a>, <a href="/facts/Probability_theory/mFBn51rE">probability</a>, and <a href="/facts/Game_theory/zkEIj1ya">game theory</a>. It is closely tied to many of the most important theorems in these fields, including <a href="/facts/Arrow%27s_impossibility_theorem/PD9oI3ky">Arrow's impossibility theorem</a>, the <a href="/facts/Balinski%E2%80%93Young_theorem/y0qJgXVs">Balinski–Young theorem</a>, and the <a href="/facts/Money_pump/6dbGmW5N">money pump arguments</a>.
</p><p>In <a href="/facts/Behavioral_economics/bbSgL7Ad">behavioral economics</a>, failures of IIA (caused by <a href="/facts/Irrationality/UQEGMC85">irrationality</a>) are called menu effects or menu dependence. 
</p>

Independence of irrelevant alternatives open-in-new

Independence of irrelevant alternatives