Define: A Posteriori

A Posteriori
A Posteriori
Quick Summary of A Posteriori

“A posteriori” is a Latin term used in philosophy and epistemology to denote knowledge that is derived from experience or empirical evidence. In contrast to “a priori” knowledge, which is based on reasoning or deduction independent of sensory experience, a posteriori knowledge relies on observation, experimentation, or perception of the external world. This type of knowledge is often associated with scientific inquiry and induction, where conclusions are drawn from specific instances or observations to make generalisations or formulate hypotheses. A posteriori reasoning plays a fundamental role in understanding the natural world and forming beliefs based on evidence gathered through sensory experience.

What is the dictionary definition of A Posteriori?
Dictionary Definition of A Posteriori

[Latin, From the effect to the cause.]

A posteriori describes a method of reasoning from given, express observations or experiments to reach and formulate general principles from them. This is also called inductive reasoning.

Full Definition Of A Posteriori

A posteriori denotes using information obtained after an event or experience. This type of reasoning begins with what we have learned via our experiences. For example, if we are burned while touching a hot stove, we know not to do so again. A posteriori reasoning is based on what we have learned via our experiences.

In the realm of epistemology, the distinction between a priori and a posteriori knowledge plays a fundamental role in understanding the sources and nature of human understanding. While a priori knowledge is derived independently of sensory experience, a posteriori knowledge relies on empirical evidence and sensory perception. This essay delves into the concept of a posteriori knowledge, examining its philosophical implications, examples, and significance in shaping our understanding of the world.

Definition and Philosophical Significance:

The term “a posteriori” originates from Latin, meaning “from the latter.” In philosophical discourse, it refers to knowledge that is obtained through experience or empirical observation. Unlike a priori knowledge, which is based on reason and intuition, a posteriori knowledge is contingent upon sensory perception and empirical evidence derived from the external world.

The distinction between a priori and a posteriori knowledge was famously articulated by the philosopher Immanuel Kant in his seminal work, the “Critique of Pure Reason.” Kant argued that a priori knowledge is grounded in the inherent structure of the mind and is independent of experience, whereas a posteriori knowledge is contingent upon sensory experience and empirical observation.

Examples of Posteriori Knowledge:

Examples of a posteriori knowledge abound in everyday experience, ranging from empirical observations of the natural world to scientific discoveries and historical facts. Consider, for instance, the statement “The sun rises in the east.” This assertion is based on countless observations of the sun’s movement across the sky, derived from sensory experience and empirical observation.

Similarly, scientific theories and hypotheses are often formulated based on a posteriori knowledge obtained through experimentation and observation. For example, the theory of evolution proposed by Charles Darwin is grounded in empirical evidence derived from fossil records, comparative anatomy, and observations of natural selection in action.

Historical facts and events also fall under the category of a posteriori knowledge, as they are based on empirical evidence and historical documentation. For instance, the fact that Julius Caesar was assassinated in 44 BCE is derived from historical records and accounts of eyewitnesses, rather than being known a priori through pure reason.

Challenges and Limitations:

While a posteriori knowledge provides a valuable means of understanding the world, it is not without its challenges and limitations. Empirical observations are subject to interpretation and can be influenced by factors such as perspective, bias, and sensory limitations. Additionally, empirical evidence may be incomplete or inconclusive, leading to uncertainty and ambiguity in our understanding of certain phenomena.

Furthermore, reliance on a posteriori knowledge alone can lead to scepticism and epistemic uncertainty, as sensory experience is inherently fallible and subject to error. Philosophers such as David Hume have raised questions about the reliability of induction, which forms the basis of much a posteriori knowledge, highlighting the potential for error and the problem of induction.

Despite these challenges, a posteriori knowledge remains a valuable tool for acquiring understanding and knowledge about the world. Through careful observation, experimentation, and empirical inquiry, we can gain insights into the workings of the natural world, unravel the mysteries of the universe, and uncover the truths of history.

Scientific Inquiry and Progress:

The reliance on a posteriori knowledge is particularly evident in the field of science, where empirical observation and experimentation are central to the scientific method. Scientists formulate hypotheses based on existing knowledge and theories, which are then tested through experimentation and observation to gather empirical evidence.

The process of scientific inquiry relies heavily on a posteriori knowledge, as scientists seek to uncover the underlying principles governing natural phenomena through empirical observation and experimentation. This iterative process of hypothesis testing and refinement has led to significant advances in our understanding of the natural world, from the laws of physics to the complexities of biological systems.

Moreover, scientific progress depends on the accumulation of a posteriori knowledge over time, as new discoveries build upon existing theories and empirical evidence. The development of technologies such as telescopes, microscopes, and particle accelerators has expanded our ability to observe and investigate the universe, opening new avenues for scientific inquiry and discovery.

Ethical and moral considerations:

A posteriori knowledge also extends to ethical and moral considerations, as our understanding of human behaviour and societal norms is informed by empirical observation and experience. Moral judgements and ethical principles often arise from our interactions with others and our observations of the consequences of our actions.

For example, our understanding of moral principles such as fairness, justice, and empathy is shaped by our experiences of human interactions and social dynamics. Through empirical observation, we come to recognise the impact of our actions on others and develop a sense of moral responsibility towards our fellow beings.

Similarly, empirical research in fields such as psychology, sociology, and anthropology provides insights into human behaviour, social norms, and cultural practices. By studying human societies and observing patterns of behaviour, researchers can gain a deeper understanding of the factors influencing individual and collective actions, informing ethical decision-making and policy formulation.


In conclusion, a posteriori knowledge plays a crucial role in shaping our understanding of the world, from empirical observations of the natural world to scientific discoveries and historical events. Through sensory experience and empirical inquiry, we acquire knowledge about the workings of the universe, unravel the mysteries of history, and navigate the complexities of human behaviour and societal norms.

While a posteriori knowledge is subject to challenges and limitations, it remains a valuable tool for acquiring understanding and knowledge about the world. By embracing empiricism and engaging in careful observation and experimentation, we can continue to expand our horizons, deepen our understanding, and make meaningful contributions to the advancement of human knowledge and civilization.

A Posteriori FAQ'S

In legal contexts, “a posteriori” refers to evidence, arguments, or judgments that are based on empirical observation, facts, or specific circumstances rather than on pure reasoning or deduction.

A posteriori reasoning is crucial in legal decision-making as it allows judges and juries to consider real-world evidence, witness testimony, and factual circumstances when evaluating cases and reaching conclusions.

Criminal cases, civil disputes, and administrative hearings often rely heavily on a posteriori evidence, including witness testimony, physical evidence, expert opinions, and documentary proof.

A posteriori evidence plays a critical role in establishing guilt or liability by providing factual support for legal claims, demonstrating causation, and rebutting opposing arguments based on speculation or conjecture.

Lawyers and legal scholars use a posteriori reasoning to analyse case law, interpret statutes, formulate legal strategies, and present persuasive arguments grounded in real-world facts and evidence.

Yes, a posteriori evidence can be challenged in court through cross-examination, expert testimony, presentation of contradictory evidence, and arguments questioning the reliability or authenticity of the evidence.

While a posteriori evidence is valuable, its interpretation and application may be subject to biases, errors, and limitations, such as issues related to witness credibility, chain of custody, or forensic analysis.

The admissibility of a posteriori evidence varies across legal systems based on rules of evidence, procedural laws, and judicial discretion, with some jurisdictions placing stricter requirements on the reliability and relevance of evidence.

Yes, a posteriori reasoning can be used to challenge legal precedents or established legal principles by presenting new evidence, scientific discoveries, or societal developments that call into question previous interpretations or conclusions.

A posteriori evidence may be presented during alternative dispute resolution methods to support parties’ positions, facilitate negotiations, and reach mutually acceptable resolutions without the need for formal litigation.

The use of technology, such as digital forensics, surveillance footage, and data analysis tools, has significantly expanded the scope and complexity of a posteriori evidence in legal proceedings, requiring courts to adapt their procedures and standards accordingly.

Safeguards such as rules of evidence, expert testimony, judicial oversight, and the right to challenge evidence help ensure the integrity and reliability of a posteriori evidence in legal proceedings, promoting fairness and justice.

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This glossary post was last updated: 12th April 2024.

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