its more likely that party politicians result in irrational mental functioning. just look to the past PMs, inc. Rudd.
independent candidates declare their priorities and policies, while party pollies only need to give the nod to party politicise and nothing more is demanded off them. there are numerous examples of party candidates who've turned out to be destructive, eg. Latham, Rudd, Porter and Hockey. All men who climbed the greasy pole without ever demonstrating merit.
of course there are never any guarantees. its up to each individual to critically study each candidate and make an informed deciision who they should vote for. but through decades of party politics voters have been bred to take a lazy approach to elections and simply vote for the party candidate without assessment of the person's values and mental abilities.
