Why can some verbs in English be followed only by doing but not by to do?

The distinction between verbs that take a gerund (doing) versus an infinitive (to do) as their complement is a core feature of English syntax, governed by historical development, semantic patterning, and grammatical analogy rather than a single rule. This division is not arbitrary but reflects how the verb's meaning interacts with the subsequent action. Verbs that exclusively demand a gerund object, such as *enjoy*, *consider*, *avoid*, or *postpone*, typically denote an activity that is conceptualized as a general, ongoing, or completed process. The gerund, being a verb form that functions as a noun, naturally represents an action as a unitary concept or an accomplished fact. For instance, "I enjoy reading" treats *reading* as the experienced activity itself. Shifting such a verb to an infinitive ("I enjoy to read") creates a cognitive dissonance because the infinitive often carries connotations of potentiality, intention, or futurity—meanings that conflict with the semantics of a verb like *enjoy*, which is concerned with a present or habitual reaction to an actual experience.

The grammatical mechanism is one of subcategorization, where each verb is lexically specified for the type of complement clause it licenses. This specification is largely idiomatic and must be acquired through exposure, though strong semantic tendencies exist. The gerund-only class frequently includes verbs involving mental states of like or dislike (*detest*, *loathe*), verbs of avoidance or completion (*finish*, *quit*), and verbs of admission or denial (*deny*, *admit*). The resistance to the infinitive here is robust; even when an infinitive might seem logically plausible, as in a phrase like "I considered to leave," it remains ungrammatical because *consider* requires its object to be a settled matter for contemplation, not a goal to be pursued. The infinitive, by contrast, is strongly affiliated with verbs of desire, decision, or effort (*want*, *decide*, *strive*), where the action is prospective and not yet realized.

From a learning and analytical perspective, the implication is that this is a matter of lexical knowledge rather than derivable logic. For a native speaker, the correct pairing is internalized; for a learner, it presents a classic case of memorization guided by semantic clusters. Attempts to rationalize every exception often fail, as evidenced by near-synonyms that take different complements: *suggest* takes a gerund ("He suggested leaving"), while *propose* can accept both but with subtle shifts in meaning. The persistence of this distinction has implications for sentence clarity and processing. Using the wrong complement can render a sentence not merely stylistically odd but syntactically illicit, breaking the grammatical frame that listeners and readers subconsciously expect. This rigidity maintains precise boundaries between expressing an attitude toward an actual activity (gerund) and expressing an orientation toward a potential or intended one (infinitive), thereby reducing ambiguity in verbal communication.