Identify the infinitive phrase and its use.

To win an argument is seldom a desirable goal.

And you think it's ... ??

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The infinitive phrase in this sentence is "to win an argument." The use of this phrase is as the subject of the sentence. It functions as the main focus or topic of the sentence, expressing the action or intention that is being discussed. In this case, the infinitive phrase "to win an argument" serves as the subject of the sentence and indicates that the act of winning an argument is seldom a desirable goal.