In the following passage, some of the words have been left out. Read the passage carefully and select the correct answer for the given blank out of the four alternatives. Those who argue in this way support their case by pointing to the lack of a general consensus of opinion which obtains in many parts of the field which the philosopher regards as his own, and also by pointing out that, even within this field, there is a growing tendency ___________ the part of certain sciences to separate themselves from philosophy and become independent. Thus the psychologist and the logician are sometimes very anxious to have it understood that they belong among the scientists and not among the philosophers. Fill in the blank: field, there is a growing tendency ___________ the part of certain sciences to separate.

Introduction / Context:
This cloze question examines knowledge of common English prepositional phrases within a passage about philosophy and the sciences. The sentence refers to a growing tendency among certain sciences to separate themselves from philosophy. The missing preposition occurs in a fixed expression involving the word part.

Given Data / Assumptions:

• The relevant part of the sentence reads: there is a growing tendency ___________ the part of certain sciences to separate themselves from philosophy.
• In English, the standard idiom is on the part of someone, meaning on the side of or shown by that person or group.
• We must therefore choose the preposition that correctly completes this idiom.
• The options are in, on, of and for.

Concept / Approach:
The concept tested is correct use of set phrases. While several prepositions may appear plausible individually, only one forms a standard collocation with the surrounding words. Recognising that tendency on the part of is a common expression helps to select the correct option.

Step-by-Step Solution:
Step 1: Consider the whole phrase we expect: a tendency on the part of certain sciences.Step 2: Insert each option to test grammaticality and idiomatic usage: tendency in the part, tendency on the part, tendency of the part, tendency for the part.Step 3: Observe that only on the part is a standard expression to indicate behaviour or attitude coming from someone.Step 4: Choose on as the correct preposition for the blank.

Verification / Alternative check:
Check the broader structure: There is a growing tendency on the part of certain sciences to separate themselves from philosophy. This reads naturally and correctly. If we try of the part or in the part, the phrase sounds unnatural and does not convey the intended meaning of action coming from those sciences.

Why Other Options Are Wrong:
Option A, in, would give tendency in the part, which is not a recognised expression and sounds awkward.
Option C, of, would yield tendency of the part, which also fails to express that the tendency comes from those sciences.
Option D, for, would result in tendency for the part, another unidiomatic and unclear phrase.

Common Pitfalls:
Many learners focus only on the word tendency and choose a preposition they commonly use with it, such as tendency for or tendency of. However, the phrase here is more specific: on the part of, indicating an attitude, decision or action that originates from a particular group. Ignoring this collocation leads to errors.

Final Answer:
The correct preposition that completes the idiomatic phrase is on, forming on the part of certain sciences. Thus, the correct answer is on.