What do you call someone who acts "cool-headed"?

I mean someone who acts regardless of his/her feelings, according to what's the best option. I mean tough choices where your brain dictates something but your feelings might say something else.

I'm looking for an adjective that describes a character in a story. The woman leaves her twin baby daughters in a roadside in China because they had better chances of surviving there than if she carried them along - we're talking during the Japan invasion of China.

Solution 1:

I'd go with pragmatic. Since you mentioned "someone who acts regardless of his/her feelings, according to what's the best option", pragmatic seems fitting. Though a pragmatic person needn't always cast aside his/her feelings.

In the situation that you've mentioned,

[A] woman leaves her twin baby daughters in a roadside in China because they had better chances of surviving there than if she carried them along.

the woman can be described as being "rational".

Someone who is rational chooses the best possible way out of a problem. Wikipedia explains rationality as:

the quality or state of being reasonable, based on facts or reason. Rationality implies the conformity of one's beliefs with one's reasons to believe, or of one's actions with one's reasons for action.

Unsentimental can also be used.

Unsentimental

• facing facts or difficulties realistically and with determination

• not tending to indulge the emotions excessively

Solution 2:

Several suggestions:

Dispassionate

not influenced or affected by emotions

Calculating

marked by prudent analysis or by shrewd consideration of self-interest