The antonyms for the phrase "considering closely" could vary depending upon the context of its usage. However, some common antonyms are "superficially," "hastily," "carelessly," "negligently," and "lightly." These antonyms signify the opposite of closely considering or analyzing something. When you consider something closely, you analyze it thoroughly, whereas, when you do something hastily, you do it without proper evaluation. When you consider something superficially, you only skim through its surface without delving deep. Similarly, when you are careless, you overlook or ignore important aspects, whereas, when you are negligent or light in your approach, you may miss critical details.