The answer has nothing to do with their cause, however, but with the simple fact that dictionaries are not exercises in bi-unique substitutability; in other words, if one of the senses of run is `operate' (as in She runs an engine factory ), that does not make it valid to assume that one can substitute operate for run in We run in the marathon every year .  Although recognizing this as a shortcoming of dictionaries and assigning it arbitrarily to what, for lack of a better term, we might call the  genius  of the language, might seem trivial to the casual observer, it is a valid matter for concern in the realm of lexicology.
( ( ( ( ( ( The answer ) ( ( ( ( has nothing ) ( to ( do ( with ( their cause ) ) ) ) ) , ) however ) ) , ) but ) ( ( with ( ( ( ( ( ( ( ( the ( simple fact ) ) ( that ( dictionaries ( ( are not ) ( exercises ( in ( bi-unique substitutability ) ) ) ) ) ) ) ; ) ( in ( ( ( other words ) , ) ( if ( ( one ( of ( ( the senses ) ( of run ) ) ) ) ( ( is ` ) ( ( ( ( operate ' ) -LRB- ) ( as ( in ( She ( runs ( an ( engine factory ) ) ) ) ) ) ) -RRB- ) ) ) ) ) ) ) , ) ( that ( ( does not ) ( ( make it ) ( ( valid ( to ( assume ( that ( one ( can ( substitute ( ( operate ( for run ) ) ( in ( We ( ( run ( in ( ( the marathon ) ( every year ) ) ) ) . ) ) ) ) ) ) ) ) ) ) ) ( Although ( ( ( ( recognizing this ) ( as ( ( a shortcoming ) ( of dictionaries ) ) ) ) and ) ( ( ( assigning it ) arbitrarily ) ( to ( what ( , ( ( for ( lack ( of ( a ( better term ) ) ) ) ) ( , ( we ( might ( call ( ( the genius ) ( of ( the language ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) , ) ( might ( seem ( trivial ( to ( the ( casual observer ) ) ) ) ) ) ) ) ( , ( it ( is ( ( a ( valid matter ) ) ( for ( concern ( in ( ( the realm ) ( of lexicology ) ) ) ) ) ) ) ) ) ) ) . )
(ROOT (S (S (NP (DT The) (NN answer)) (VP (VBZ has) (ADVP (NN nothing)) (S (VP (TO to) (VP (VB do) (PP (IN with) (NP (PRP$ their) (NN cause)))))) (, ,) (ADVP (RB however)))) (, ,) (CC but) (S (SBAR (IN with) (S (NP (NP (DT the) (JJ simple) (NN fact)) (SBAR (IN that) (S (NP (NNS dictionaries)) (VP (VBP are) (RB not) (NP (NP (NNS exercises)) (PP (IN in) (NP (JJ bi-unique) (NN substitutability))))))) (: ;) (PP (IN in) (NP (NP (JJ other) (NNS words)) (, ,) (SBAR (IN if) (S (NP (NP (CD one)) (PP (IN of) (NP (NP (DT the) (NNS senses)) (PP (IN of) (NP (NN run)))))) (VP (VBZ is) (`` `) (VP (VB operate) ('' ') (-LRB- -LRB-) (SBAR (RB as) (IN in) (S (NP (PRP She)) (VP (VBZ runs) (NP (DT an) (NN engine) (NN factory))))) (-RRB- -RRB-))))))) (, ,) (SBAR (WHNP (WDT that)) (S (VP (VBZ does) (RB not) (VP (VB make) (NP (PRP it)) (S (ADJP (JJ valid) (S (VP (TO to) (VP (VB assume) (SBAR (IN that) (S (NP (PRP one)) (VP (MD can) (VP (VB substitute) (VP (VB operate) (PP (IN for) (NP (NN run))) (SBAR (IN in) (S (NP (PRP We)) (VP (VB run) (PP (IN in) (NP (NP (DT the) (NN marathon)) (NP (DT every) (NN year)))) (. .))))))))))))) (SBAR (IN Although) (S (S (VP (VBG recognizing) (NP (DT this)) (PP (IN as) (NP (NP (DT a) (NN shortcoming)) (PP (IN of) (NP (NNS dictionaries))))))) (CC and) (S (VP (VBG assigning) (NP (PRP it)) (ADVP (RB arbitrarily)) (PP (TO to) (SBAR (WHNP (WP what)) (S (, ,) (PP (IN for) (NP (NP (NN lack)) (PP (IN of) (NP (DT a) (JJR better) (NN term))))) (, ,) (NP (PRP we)) (VP (MD might) (VP (VB call) (NP (NP (DT the) (NN genius)) (PP (IN of) (NP (DT the) (NN language)))))))))))))))))) (, ,)) (VP (MD might) (VP (VB seem) (ADJP (JJ trivial) (PP (TO to) (NP (DT the) (JJ casual) (NN observer)))))))) (, ,) (NP (PRP it)) (VP (VBZ is) (NP (NP (DT a) (JJ valid) (NN matter)) (PP (IN for) (NP (NP (NN concern)) (PP (IN in) (NP (NP (DT the) (NN realm)) (PP (IN of) (NP (NN lexicology)))))))))) (. .)))
The answer given is irrelevant to their cause.
( ( ( The answer ) given ) ( ( is ( irrelevant ( to ( their cause ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (NN answer)) (VP (VBN given))) (VP (VBZ is) (ADJP (JJ irrelevant) (PP (TO to) (NP (PRP$ their) (NN cause))))) (. .)))