Our Gemara on amud aleph lists various criteria that describe an ignoramus (in Torah), as called by the Gemara, an Am-Ha’aretz:

תָּנוּ רַבָּנַן: אֵיזֶהוּ עַם הָאָרֶץ? כֹּל שֶׁאֵינוֹ קוֹרֵא קְרִיאַת שְׁמַע שַׁחֲרִית וְעַרְבִית בְּבִרְכוֹתֶיהָ, דִּבְרֵי רַבִּי מֵאִיר. וַחֲכָמִים אוֹמְרִים: כֹּל שֶׁאֵינוֹ מַנִּיחַ תְּפִילִּין. בֶּן עַזַּאי אוֹמֵר: כֹּל שֶׁאֵין לוֹ צִיצִית בְּבִגְדוֹ. רַבִּי יוֹנָתָן בֶּן יוֹסֵף אָמַר: כֹּל שֶׁיֵּשׁ לוֹ בָּנִים וְאֵינוֹ מְגַדְּלָן לִלְמוֹד תּוֹרָה. אֲחֵרִים אוֹמְרִים: אֲפִילּוּ קוֹרֵא וְשׁוֹנֶה וְלֹא שִׁימֵּשׁ תַּלְמִידֵי חֲכָמִים — זֶהוּ עַם הָאָרֶץ.

The Sages taught: Who is an ignoramus [am ha’aretz]? It is anyone who does not recite Shema in the morning and evening with its blessings; this is the statement of Rabbi Meir. And the Rabbis say: It is anyone who does not don phylacteries. Ben Azzai says: It is anyone who does not have ritual fringes on his garment. Rabbi Yonasan ben Yosef said: It is anyone who has sons and does not raise them to study Torah. Aḥerim say: Even if one reads the Written Torah and learns the Mishna but does not serve Torah scholars, he is an ignoramus...

תָּנָא: הַתַּנָּאִים — מְבַלֵּי עוֹלָם. מְבַלֵּי עוֹלָם סָלְקָא דַּעְתָּךְ?! אָמַר רָבִינָא: שֶׁמּוֹרִין הֲלָכָה מִתּוֹךְ מִשְׁנָתָן. תַּנְיָא נָמֵי הָכִי, אָמַר רַבִּי יְהוֹשֻׁעַ: וְכִי מְבַלֵּי עוֹלָם הֵן? וַהֲלֹא מְיַישְּׁבֵי עוֹלָם הֵן, שֶׁנֶּאֱמַר: ״הֲלִיכוֹת עוֹלָם לוֹ״! אֶלָּא, שֶׁמּוֹרִין הֲלָכָה מִתּוֹךְ מִשְׁנָתָן.

It was taught in a baraisa: The tanna’im, who recite the tannaitic sources by rote, are individuals who erode the world. (Note: this word “Tanaim” is referring to the savants who memorized the teachings and not referring to the Rabbis of the Mishna.)  The Gemara is puzzled by this statement: Could it enter your mind that they are individuals who erode the world? Ravina says: This statement is referring to those who issue halakhic rulings based on their knowledge of mishnayos. This is also taught in a baraita: Rabbi Yehoshua said: Are they individuals who erode the world? Aren’t they settling the world, as it is stated: “His ways [halikhos] are eternal” (Habakkuk 3:6)? The Sages read the term halikhos as halakhos, inferring that one who learns halakhos attains eternal life. Rather, this is referring to those who issue halakhic rulings based on their knowledge of mishnayos.

The Maharal (Nesivos Olam, Nesiv Ha-Torah 15) explains that the various criteria described by the Gemara which define a person as an am ha’aretz, although seemingly widely different, actually refer to the same concept. Rabbi Meir set the bar at the recitation of Shema because the moment he accepts the yoke of heaven, he has already established his existence beyond an animalistic physical level. The Chachamim similarly use the same idea, just one notch higher, and that is when the person wears tefilin. This too, is indicative of accepting the yoke of heaven, and elevating his existence. Ben Azzai has a similar criterion, however unlike tefilin which only covers strategic parts of the body, he requires the person to be wearing Tzitzis, which is a garment encompassing his entire physicality. Rabbi Yonasan’s criteria seems the most divergent, however, this too maintains the Maharal, is about leading a spiritual existence. If one cannot guide his progeny in the ways of the Torah, then his life was not grounded in spirituality. Then we moved to the final level, that of the “acherim”, the “other opinion” which I’m assuming is identified as “others” because it represents an extreme level that is not for everyone, but nevertheless, an important distinction. Even a person who understands Torah well and deep, without having spent time apprenticing with an elder Sage will be missing in understanding how to apply the Torah on a practical level and will make mistakes due to lack of awareness of nuances and what is called “the fifth Shulkhan Arukh”. 

The Maharal then connects this to the additional statement of the Gemara, which describes those who render halakhic decisions from the memorized codes of the Mishna without deep understanding, as destroying the world. The Maharal famously goes on criticize the trend of the halachic codes of his day because he felt this would lead to an ossification of the dynamic halachic process:

They destroy the world because they offer halachic rulings from their rote memorized teachings...This means that they pasken from their teachings without understanding the basis of their rulings. This is why they destroy the world because they are destroying Torah when they do this, as this is not real Torah. 

It is only real Torah when you decide based on your intellectual understanding...In our generation it would be bad enough if they ruled from the Mishna, which at least is the beginning of the Talmudic analytic process, but worse, they rule from codes which are not designed to teach Torah but rather to offer halachic guides. This state of affairs is contrary to proper thinking. True, the early authorities such as the Rambam and the Tur also wrote codes and didn't provide their analysis, but their intention was to show the halacha they arrived at through the intellectual and analytic process of studying the sources. It never was their intention that a person should rule from their codes without knowing the underlying reason. If they thought that their writings would have led people to abandon studying Gemara and deciding halacha from merely external texts, they never would have written it. 

And here we find one of the most remarkable statements from the Maharal:

It is far better to rule halacha from studying the Gemara even if it is possible that one might rule incorrectly. The scholar only can know what his intellect shows him from his analysis -- and even his albeit mistaken ruling is beloved to Hashem, may He be blessed. The judge only can judge from what his eyes see. This is far preferable than to rule from a composition without knowing any of the real reasons, to be as a blind man who gropes along the path.