To argue against it, I would say: there are many sides to onesidedness. At least many variations.

- One sided onesidedness:

Also called: fundamental sidetaking. This is having one opinion. Do not consider other possibilities, just act on that which you don't question. This is the Taliban fun of blowing up valuable utterings of other views.

Oh, this is totally it.

- Twosided onesidedness:

Also called: political sidetaking. Cling to your opinion, but investigate other possibilities so as to know how to attack them best. Always interpret the possible value and meaning of other views into the structure of your own. Never really leave it, but pretend you see the case in more than one way.

Oh yes, I was definitely right before.

- Multisided onesidedness:

Also called: dynamic sidetaking. Seriously investigate your own opinion and compare it in details against others, trying to avoid bias. The result will be that your initial opinion will change over to another, then again to another. In this so-called dialectic, the resulting opinion superficially may or may not resemble the initial one, but the outcome is bound to be more ripe, mature, subtle.

          I didn’t have to be, but I was.

- Currentsided onesidedness:

Also called: the time is now. In your path of opinions, there will be moments you have to act. If this involves convincing others, make the best use of metaphors to present your current view as clear and powerful as possible. But as you know this is only now, and later you may get better opinions, be careful not to do things that cannot be undone, like killing.

Everything is pointing toward this conclusion.

- Farsided onesidedness:

Also called: artistic sidetaking. Blow up your own opinion. Exaggerate until you made a caricature of all values of your opinion while barely maintaining plausibility.

Which is exactly why I was wrong.

- Metasided onesidedness:

Also called: make a mess. Combine all onesidednesses as stated above, according to your momentarily flavour. Especially farsided and fundamentally sided will give an explosive mixture.

And why I was right.

On the other hand: currentsidedness and dynamic onesidedness go nicely hand in hand.

And you should probably act now.