( ( 3 -RRB- ) ( ( Parsimony ( If ( ( two theories ) ( ( explain ( ( a set ) ( of observations ) ) ) ( equally well ) ) ) ) ) ( , ( ( ( the ( simpler theory ) ) ( -LRB- ( ( ( the one ) ( that ( ( explains ( the facts ) ) ( with ( the ( fewest ( ( mechanisms or ) assumptions ) ) ) ) ) ) ) -RRB- ) ) ) ( ( is preferred ) . ) ) ) ) )
(ROOT (S (LST (LS 3) (-RRB- -RRB-)) (SBAR (ADVP (RB Parsimony)) (IN If) (S (NP (CD two) (NNS theories)) (VP (VBP explain) (NP (NP (DT a) (NN set)) (PP (IN of) (NP (NNS observations)))) (ADVP (RB equally) (RB well))))) (, ,) (NP (NP (DT the) (JJR simpler) (NN theory)) (PRN (-LRB- -LRB-) (NP (NP (DT the) (NN one)) (SBAR (WHNP (WDT that)) (S (VP (VBZ explains) (NP (DT the) (NNS facts)) (PP (IN with) (NP (DT the) (JJ fewest) (NNS mechanisms) (CC or) (NNS assumptions))))))) (-RRB- -RRB-))) (VP (VBZ is) (ADJP (JJ preferred))) (. .)))
3) Parsimony If two theories explain a set of observations equally well, the simpler theory (the one that explains the facts with the fewest mechanisms or assumptions) is preferred.
(ROOT (S (NP (NP (DT The) (NN law)) (PP (IN of) (NP (NN parsimony)))) (VP (VBZ is) (NP (NP (DT the) (JJ scientific) (NN concept)) (VP (VBG stating) (SBAR (IN that) (S (SBAR (WHADVP (WRB when)) (S (VP (VBG looking) (PP (IN at) (NP (CD two))) (NP (VBG competing) (NNS theories))))) (, ,) (NP (NP (DT the) (NN one)) (PP (IN with) (NP (JJR fewer) (NNS assumptions)))) (VP (MD should) (VP (VB be) (VP (VBN chosen))))))))) (. .)))