Short answers, pulled from the story.
Thought, in its most common sense, refers to conscious cognitive processes that occur independently of direct sensory stimulation, such as judging, reasoning, concept formation, problem solving, and deliberation. Memory and imagination count as forms of thought in this sense, while perception does not. The terms can also denote the results of these processes, such as beliefs, mental states, or systems of ideas.
The main theories include Platonism, which holds that thinking discerns eternal forms; Aristotelianism and conceptualism, which tie thinking to instantiating essences or evoking concepts; inner speech theories and the language of thought hypothesis; associationism; behaviorism; and computationalism. These theories are not necessarily mutually exclusive and some can be combined without contradiction.
The language of thought hypothesis, introduced by Jerry Fodor, states that thinking happens in the medium of a mental language often called Mentalese. It claims thought is built from atomic and compound representations combined by syntactic rules, where a compound's meaning depends on its parts. Fodor argues it best explains features of thinking such as productivity, systematicity, and inferential coherence.
The laws of thought traditionally refer to three fundamental laws of logic: the law of contradiction, the law of excluded middle, and the principle of identity. Aristotle held the law of excluded middle false for uncertain future events, intuitionist logic also rejects it, and dialetheists reject the law of contradiction. Some formulations add a fourth, the principle of sufficient reason.
The Chinese room is a thought experiment proposed by John Searle in which a person who does not know Chinese sits in a closed room replying to Chinese messages using a giant rule book. Searle argues that neither the person nor a computer truly understands Chinese, aiming to show that computers lack a mind capable of deeper understanding despite acting intelligently.
Counterfactual thinking represents non-actual situations contrary to the facts and answers What if questions, often producing regret through upward counterfactuals or relief through downward counterfactuals. Critical thinking is reasonable, reflective thinking focused on determining what to believe or how to act, holding itself to standards of clarity and rationality through meta-cognitive checks.
Sigmund Freud's structural model divides the psyche into the id, ego, and super-ego, and treats the unconscious as what is actively repressed, a force recognized only by its effects. Carl Jung coined the collective unconscious, a reservoir of the experiences of our species shared across humanity, an idea Freud did not accept.