Principal Scientist, Large Language Reasoning

At Johnson & Johnson, we believe health is everything. Our strength in healthcare innovation empowers us to build a world where complex diseases are prevented, treated, and cured, where treatments are smarter and less invasive, and solutions are personal. Through our expertise in Innovative Medicine and MedTech, we are uniquely positioned to innovate across the full spectrum of healthcare solutions today to deliver the breakthroughs of tomorrow, and profoundly impact health for humanity. Learn more at

Job Function:

Data Analytics & Computational Sciences

Job Sub Function:

Data Science

Job Category:

Scientific/Technology

All Job Posting Locations:

Berlin, Germany, Cornellà de Llobregat, Barcelona, Spain, Madrid, Spain, NEUSS, Germany

Job Description:

Johnson & Johnson Innovative Medicine (J&J IM) is recruiting for the role of Principal Scientist – Large Language Reasoning for Drug Discovery. The primary location for this role is Barcelona / Madrid, Spain with secondary location being considered in Germany.

J&J IM develops treatments that improve the health and well-being of people worldwide. Research and development areas encompass oncology, cardiovascular and retina disorders, immunology, and neuroscience. Our goal is to help people live longer and healthier lives. We have produced and marketed many first-in-class prescription medications and are poised to serve the broad needs of the healthcare market – from patients to practitioners and from clinics to hospitals. To learn more about J&J IM, please visit

The Machine Intelligence (MI) team within Data Science and Digital Health (DSDH) AI/ML is seeking a visionary Principal Scientist to architect autonomous AI in drug discovery and development. You'll pioneer innovative work with Large Language Models (LLMs) and agentic systems, harnessing large scale datasets spanning scientific literature, omics, biomolecular knowledge, and manufacturing processes to fundamentally transform how we bring therapeutics to patients. Your innovations in areas such as multimodal reasoning, agent adaptability and uncertainty, memory architecture, and motivation frameworks will directly compress discovery timelines and accelerate promising therapeutics from hypothesis to clinical trials.

Key Responsibilities:

• Pioneer breakthrough multimodal AI systems that synthesize scientific data into actionable scientific insights which accelerate drug discovery

• Architect next-generation agent memory systems that establish how AI retains knowledge and makes context-aware decisions, creating persistent intelligence that evolves across the entire discovery-to-development pipeline

• Define the future of AI reliability in R&D by orchestrating groundbreaking research in uncertainty quantification and establishing new standards for trustworthy AI-driven scientific reasoning

• Shape the scientific vision as an inspiring leader, translating emerging AI/ML frontiers into transformative applications while mentoring teams to push the boundaries of what's possible in computational drug discovery

• Drive scientific validation and impact by rigorously benchmarking AI agents against top human experts and state-of-the-art methods, with the opportunity to publish paradigm-shifting findings in premier venues

Required qualifications:

• Ph.D. in AI/ML or related fields (computer science, machine learning, data science, applied mathematics, statistics) with 2+ years of proven experience

• Deep expertise in sophisticated mathematical frameworks including Bayesian inference, uncertainty quantification, information theory, causal inference, graph neural networks, and related methodologies that advance the field of agentic reasoning

• Proficiency with agentic frameworks (LangGraph, DSPy, mem0) and deep learning platforms (PyTorch, TensorFlow), and extend these tools for novel scientific applications

• Exceptional Python programming skills, capable of architecting scalable solutions that bridge innovation and production deployment

• The ability to lead small teams of researchers to achieve success in their work

Preferred ("nice-to-have") qualifications:

• Understanding of drug discovery pipeline and familiarity with biological data types

• Strong understanding of statistics and applicable methods to validate model performance

• Familiarity with cloud hosting solutions (ex. AWS and/or Azure)

Johnson & Johnson is an Affirmative Action and Equal Opportunity Employer. All qualified applicants will receive consideration for employment without regard to race, color, religion, sex, sexual orientation, gender identity, age, national origin, and will not be discriminated against on the basis of disability.

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